| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Tom Lendacky | 3312 | 41.10% | 21 | 28.38% |
| Joerg Roedel | 2197 | 27.26% | 26 | 35.14% |
| Brijesh Singh | 1696 | 21.05% | 10 | 13.51% |
| Michael Roth | 411 | 5.10% | 5 | 6.76% |
| Kirill A. Shutemov | 188 | 2.33% | 1 | 1.35% |
| Michael Sterritt | 134 | 1.66% | 1 | 1.35% |
| Borislav Petkov | 101 | 1.25% | 6 | 8.11% |
| Martin Radev | 11 | 0.14% | 1 | 1.35% |
| Peter Gonda | 6 | 0.07% | 1 | 1.35% |
| Peter Zijlstra | 1 | 0.01% | 1 | 1.35% |
| Thomas Gleixner | 1 | 0.01% | 1 | 1.35% |
| Total | 8058 | 74 |
// SPDX-License-Identifier: GPL-2.0-only /* * AMD Memory Encryption Support * * Copyright (C) 2019 SUSE * * Author: Joerg Roedel <jroedel@suse.de> */ #define pr_fmt(fmt) "SEV: " fmt #include <linux/sched/debug.h> /* For show_regs() */ #include <linux/percpu-defs.h> #include <linux/cc_platform.h> #include <linux/printk.h> #include <linux/mm_types.h> #include <linux/set_memory.h> #include <linux/memblock.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/cpumask.h> #include <linux/efi.h> #include <linux/platform_device.h> #include <linux/io.h> #include <asm/cpu_entry_area.h> #include <asm/stacktrace.h> #include <asm/sev.h> #include <asm/insn-eval.h> #include <asm/fpu/xcr.h> #include <asm/processor.h> #include <asm/realmode.h> #include <asm/setup.h> #include <asm/traps.h> #include <asm/svm.h> #include <asm/smp.h> #include <asm/cpu.h> #include <asm/apic.h> #include <asm/cpuid.h> #include <asm/cmdline.h> #define DR7_RESET_VALUE 0x400 /* AP INIT values as documented in the APM2 section "Processor Initialization State" */ #define AP_INIT_CS_LIMIT 0xffff #define AP_INIT_DS_LIMIT 0xffff #define AP_INIT_LDTR_LIMIT 0xffff #define AP_INIT_GDTR_LIMIT 0xffff #define AP_INIT_IDTR_LIMIT 0xffff #define AP_INIT_TR_LIMIT 0xffff #define AP_INIT_RFLAGS_DEFAULT 0x2 #define AP_INIT_DR6_DEFAULT 0xffff0ff0 #define AP_INIT_GPAT_DEFAULT 0x0007040600070406ULL #define AP_INIT_XCR0_DEFAULT 0x1 #define AP_INIT_X87_FTW_DEFAULT 0x5555 #define AP_INIT_X87_FCW_DEFAULT 0x0040 #define AP_INIT_CR0_DEFAULT 0x60000010 #define AP_INIT_MXCSR_DEFAULT 0x1f80 /* For early boot hypervisor communication in SEV-ES enabled guests */ static struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE); /* * Needs to be in the .data section because we need it NULL before bss is * cleared */ static struct ghcb *boot_ghcb __section(".data"); /* Bitmap of SEV features supported by the hypervisor */ static u64 sev_hv_features __ro_after_init; /* #VC handler runtime per-CPU data */ struct sev_es_runtime_data { struct ghcb ghcb_page; /* * Reserve one page per CPU as backup storage for the unencrypted GHCB. * It is needed when an NMI happens while the #VC handler uses the real * GHCB, and the NMI handler itself is causing another #VC exception. In * that case the GHCB content of the first handler needs to be backed up * and restored. */ struct ghcb backup_ghcb; /* * Mark the per-cpu GHCBs as in-use to detect nested #VC exceptions. * There is no need for it to be atomic, because nothing is written to * the GHCB between the read and the write of ghcb_active. So it is safe * to use it when a nested #VC exception happens before the write. * * This is necessary for example in the #VC->NMI->#VC case when the NMI * happens while the first #VC handler uses the GHCB. When the NMI code * raises a second #VC handler it might overwrite the contents of the * GHCB written by the first handler. To avoid this the content of the * GHCB is saved and restored when the GHCB is detected to be in use * already. */ bool ghcb_active; bool backup_ghcb_active; /* * Cached DR7 value - write it on DR7 writes and return it on reads. * That value will never make it to the real hardware DR7 as debugging * is currently unsupported in SEV-ES guests. */ unsigned long dr7; }; struct ghcb_state { struct ghcb *ghcb; }; static DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data); DEFINE_STATIC_KEY_FALSE(sev_es_enable_key); static DEFINE_PER_CPU(struct sev_es_save_area *, sev_vmsa); struct sev_config { __u64 debug : 1, __reserved : 63; }; static struct sev_config sev_cfg __read_mostly; static __always_inline bool on_vc_stack(struct pt_regs *regs) { unsigned long sp = regs->sp; /* User-mode RSP is not trusted */ if (user_mode(regs)) return false; /* SYSCALL gap still has user-mode RSP */ if (ip_within_syscall_gap(regs)) return false; return ((sp >= __this_cpu_ist_bottom_va(VC)) && (sp < __this_cpu_ist_top_va(VC))); } /* * This function handles the case when an NMI is raised in the #VC * exception handler entry code, before the #VC handler has switched off * its IST stack. In this case, the IST entry for #VC must be adjusted, * so that any nested #VC exception will not overwrite the stack * contents of the interrupted #VC handler. * * The IST entry is adjusted unconditionally so that it can be also be * unconditionally adjusted back in __sev_es_ist_exit(). Otherwise a * nested sev_es_ist_exit() call may adjust back the IST entry too * early. * * The __sev_es_ist_enter() and __sev_es_ist_exit() functions always run * on the NMI IST stack, as they are only called from NMI handling code * right now. */ void noinstr __sev_es_ist_enter(struct pt_regs *regs) { unsigned long old_ist, new_ist; /* Read old IST entry */ new_ist = old_ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]); /* * If NMI happened while on the #VC IST stack, set the new IST * value below regs->sp, so that the interrupted stack frame is * not overwritten by subsequent #VC exceptions. */ if (on_vc_stack(regs)) new_ist = regs->sp; /* * Reserve additional 8 bytes and store old IST value so this * adjustment can be unrolled in __sev_es_ist_exit(). */ new_ist -= sizeof(old_ist); *(unsigned long *)new_ist = old_ist; /* Set new IST entry */ this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], new_ist); } void noinstr __sev_es_ist_exit(void) { unsigned long ist; /* Read IST entry */ ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]); if (WARN_ON(ist == __this_cpu_ist_top_va(VC))) return; /* Read back old IST entry and write it to the TSS */ this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], *(unsigned long *)ist); } /* * Nothing shall interrupt this code path while holding the per-CPU * GHCB. The backup GHCB is only for NMIs interrupting this path. * * Callers must disable local interrupts around it. */ static noinstr struct ghcb *__sev_get_ghcb(struct ghcb_state *state) { struct sev_es_runtime_data *data; struct ghcb *ghcb; WARN_ON(!irqs_disabled()); data = this_cpu_read(runtime_data); ghcb = &data->ghcb_page; if (unlikely(data->ghcb_active)) { /* GHCB is already in use - save its contents */ if (unlikely(data->backup_ghcb_active)) { /* * Backup-GHCB is also already in use. There is no way * to continue here so just kill the machine. To make * panic() work, mark GHCBs inactive so that messages * can be printed out. */ data->ghcb_active = false; data->backup_ghcb_active = false; instrumentation_begin(); panic("Unable to handle #VC exception! GHCB and Backup GHCB are already in use"); instrumentation_end(); } /* Mark backup_ghcb active before writing to it */ data->backup_ghcb_active = true; state->ghcb = &data->backup_ghcb; /* Backup GHCB content */ *state->ghcb = *ghcb; } else { state->ghcb = NULL; data->ghcb_active = true; } return ghcb; } static inline u64 sev_es_rd_ghcb_msr(void) { return __rdmsr(MSR_AMD64_SEV_ES_GHCB); } static __always_inline void sev_es_wr_ghcb_msr(u64 val) { u32 low, high; low = (u32)(val); high = (u32)(val >> 32); native_wrmsr(MSR_AMD64_SEV_ES_GHCB, low, high); } static int vc_fetch_insn_kernel(struct es_em_ctxt *ctxt, unsigned char *buffer) { return copy_from_kernel_nofault(buffer, (unsigned char *)ctxt->regs->ip, MAX_INSN_SIZE); } static enum es_result __vc_decode_user_insn(struct es_em_ctxt *ctxt) { char buffer[MAX_INSN_SIZE]; int insn_bytes; insn_bytes = insn_fetch_from_user_inatomic(ctxt->regs, buffer); if (insn_bytes == 0) { /* Nothing could be copied */ ctxt->fi.vector = X86_TRAP_PF; ctxt->fi.error_code = X86_PF_INSTR | X86_PF_USER; ctxt->fi.cr2 = ctxt->regs->ip; return ES_EXCEPTION; } else if (insn_bytes == -EINVAL) { /* Effective RIP could not be calculated */ ctxt->fi.vector = X86_TRAP_GP; ctxt->fi.error_code = 0; ctxt->fi.cr2 = 0; return ES_EXCEPTION; } if (!insn_decode_from_regs(&ctxt->insn, ctxt->regs, buffer, insn_bytes)) return ES_DECODE_FAILED; if (ctxt->insn.immediate.got) return ES_OK; else return ES_DECODE_FAILED; } static enum es_result __vc_decode_kern_insn(struct es_em_ctxt *ctxt) { char buffer[MAX_INSN_SIZE]; int res, ret; res = vc_fetch_insn_kernel(ctxt, buffer); if (res) { ctxt->fi.vector = X86_TRAP_PF; ctxt->fi.error_code = X86_PF_INSTR; ctxt->fi.cr2 = ctxt->regs->ip; return ES_EXCEPTION; } ret = insn_decode(&ctxt->insn, buffer, MAX_INSN_SIZE, INSN_MODE_64); if (ret < 0) return ES_DECODE_FAILED; else return ES_OK; } static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt) { if (user_mode(ctxt->regs)) return __vc_decode_user_insn(ctxt); else return __vc_decode_kern_insn(ctxt); } static enum es_result vc_write_mem(struct es_em_ctxt *ctxt, char *dst, char *buf, size_t size) { unsigned long error_code = X86_PF_PROT | X86_PF_WRITE; /* * This function uses __put_user() independent of whether kernel or user * memory is accessed. This works fine because __put_user() does no * sanity checks of the pointer being accessed. All that it does is * to report when the access failed. * * Also, this function runs in atomic context, so __put_user() is not * allowed to sleep. The page-fault handler detects that it is running * in atomic context and will not try to take mmap_sem and handle the * fault, so additional pagefault_enable()/disable() calls are not * needed. * * The access can't be done via copy_to_user() here because * vc_write_mem() must not use string instructions to access unsafe * memory. The reason is that MOVS is emulated by the #VC handler by * splitting the move up into a read and a write and taking a nested #VC * exception on whatever of them is the MMIO access. Using string * instructions here would cause infinite nesting. */ switch (size) { case 1: { u8 d1; u8 __user *target = (u8 __user *)dst; memcpy(&d1, buf, 1); if (__put_user(d1, target)) goto fault; break; } case 2: { u16 d2; u16 __user *target = (u16 __user *)dst; memcpy(&d2, buf, 2); if (__put_user(d2, target)) goto fault; break; } case 4: { u32 d4; u32 __user *target = (u32 __user *)dst; memcpy(&d4, buf, 4); if (__put_user(d4, target)) goto fault; break; } case 8: { u64 d8; u64 __user *target = (u64 __user *)dst; memcpy(&d8, buf, 8); if (__put_user(d8, target)) goto fault; break; } default: WARN_ONCE(1, "%s: Invalid size: %zu\n", __func__, size); return ES_UNSUPPORTED; } return ES_OK; fault: if (user_mode(ctxt->regs)) error_code |= X86_PF_USER; ctxt->fi.vector = X86_TRAP_PF; ctxt->fi.error_code = error_code; ctxt->fi.cr2 = (unsigned long)dst; return ES_EXCEPTION; } static enum es_result vc_read_mem(struct es_em_ctxt *ctxt, char *src, char *buf, size_t size) { unsigned long error_code = X86_PF_PROT; /* * This function uses __get_user() independent of whether kernel or user * memory is accessed. This works fine because __get_user() does no * sanity checks of the pointer being accessed. All that it does is * to report when the access failed. * * Also, this function runs in atomic context, so __get_user() is not * allowed to sleep. The page-fault handler detects that it is running * in atomic context and will not try to take mmap_sem and handle the * fault, so additional pagefault_enable()/disable() calls are not * needed. * * The access can't be done via copy_from_user() here because * vc_read_mem() must not use string instructions to access unsafe * memory. The reason is that MOVS is emulated by the #VC handler by * splitting the move up into a read and a write and taking a nested #VC * exception on whatever of them is the MMIO access. Using string * instructions here would cause infinite nesting. */ switch (size) { case 1: { u8 d1; u8 __user *s = (u8 __user *)src; if (__get_user(d1, s)) goto fault; memcpy(buf, &d1, 1); break; } case 2: { u16 d2; u16 __user *s = (u16 __user *)src; if (__get_user(d2, s)) goto fault; memcpy(buf, &d2, 2); break; } case 4: { u32 d4; u32 __user *s = (u32 __user *)src; if (__get_user(d4, s)) goto fault; memcpy(buf, &d4, 4); break; } case 8: { u64 d8; u64 __user *s = (u64 __user *)src; if (__get_user(d8, s)) goto fault; memcpy(buf, &d8, 8); break; } default: WARN_ONCE(1, "%s: Invalid size: %zu\n", __func__, size); return ES_UNSUPPORTED; } return ES_OK; fault: if (user_mode(ctxt->regs)) error_code |= X86_PF_USER; ctxt->fi.vector = X86_TRAP_PF; ctxt->fi.error_code = error_code; ctxt->fi.cr2 = (unsigned long)src; return ES_EXCEPTION; } static enum es_result vc_slow_virt_to_phys(struct ghcb *ghcb, struct es_em_ctxt *ctxt, unsigned long vaddr, phys_addr_t *paddr) { unsigned long va = (unsigned long)vaddr; unsigned int level; phys_addr_t pa; pgd_t *pgd; pte_t *pte; pgd = __va(read_cr3_pa()); pgd = &pgd[pgd_index(va)]; pte = lookup_address_in_pgd(pgd, va, &level); if (!pte) { ctxt->fi.vector = X86_TRAP_PF; ctxt->fi.cr2 = vaddr; ctxt->fi.error_code = 0; if (user_mode(ctxt->regs)) ctxt->fi.error_code |= X86_PF_USER; return ES_EXCEPTION; } if (WARN_ON_ONCE(pte_val(*pte) & _PAGE_ENC)) /* Emulated MMIO to/from encrypted memory not supported */ return ES_UNSUPPORTED; pa = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT; pa |= va & ~page_level_mask(level); *paddr = pa; return ES_OK; } /* Include code shared with pre-decompression boot stage */ #include "sev-shared.c" static noinstr void __sev_put_ghcb(struct ghcb_state *state) { struct sev_es_runtime_data *data; struct ghcb *ghcb; WARN_ON(!irqs_disabled()); data = this_cpu_read(runtime_data); ghcb = &data->ghcb_page; if (state->ghcb) { /* Restore GHCB from Backup */ *ghcb = *state->ghcb; data->backup_ghcb_active = false; state->ghcb = NULL; } else { /* * Invalidate the GHCB so a VMGEXIT instruction issued * from userspace won't appear to be valid. */ vc_ghcb_invalidate(ghcb); data->ghcb_active = false; } } void noinstr __sev_es_nmi_complete(void) { struct ghcb_state state; struct ghcb *ghcb; ghcb = __sev_get_ghcb(&state); vc_ghcb_invalidate(ghcb); ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_NMI_COMPLETE); ghcb_set_sw_exit_info_1(ghcb, 0); ghcb_set_sw_exit_info_2(ghcb, 0); sev_es_wr_ghcb_msr(__pa_nodebug(ghcb)); VMGEXIT(); __sev_put_ghcb(&state); } static u64 __init get_secrets_page(void) { u64 pa_data = boot_params.cc_blob_address; struct cc_blob_sev_info info; void *map; /* * The CC blob contains the address of the secrets page, check if the * blob is present. */ if (!pa_data) return 0; map = early_memremap(pa_data, sizeof(info)); if (!map) { pr_err("Unable to locate SNP secrets page: failed to map the Confidential Computing blob.\n"); return 0; } memcpy(&info, map, sizeof(info)); early_memunmap(map, sizeof(info)); /* smoke-test the secrets page passed */ if (!info.secrets_phys || info.secrets_len != PAGE_SIZE) return 0; return info.secrets_phys; } static u64 __init get_snp_jump_table_addr(void) { struct snp_secrets_page_layout *layout; void __iomem *mem; u64 pa, addr; pa = get_secrets_page(); if (!pa) return 0; mem = ioremap_encrypted(pa, PAGE_SIZE); if (!mem) { pr_err("Unable to locate AP jump table address: failed to map the SNP secrets page.\n"); return 0; } layout = (__force struct snp_secrets_page_layout *)mem; addr = layout->os_area.ap_jump_table_pa; iounmap(mem); return addr; } static u64 __init get_jump_table_addr(void) { struct ghcb_state state; unsigned long flags; struct ghcb *ghcb; u64 ret = 0; if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) return get_snp_jump_table_addr(); local_irq_save(flags); ghcb = __sev_get_ghcb(&state); vc_ghcb_invalidate(ghcb); ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_JUMP_TABLE); ghcb_set_sw_exit_info_1(ghcb, SVM_VMGEXIT_GET_AP_JUMP_TABLE); ghcb_set_sw_exit_info_2(ghcb, 0); sev_es_wr_ghcb_msr(__pa(ghcb)); VMGEXIT(); if (ghcb_sw_exit_info_1_is_valid(ghcb) && ghcb_sw_exit_info_2_is_valid(ghcb)) ret = ghcb->save.sw_exit_info_2; __sev_put_ghcb(&state); local_irq_restore(flags); return ret; } static void pvalidate_pages(unsigned long vaddr, unsigned int npages, bool validate) { unsigned long vaddr_end; int rc; vaddr = vaddr & PAGE_MASK; vaddr_end = vaddr + (npages << PAGE_SHIFT); while (vaddr < vaddr_end) { rc = pvalidate(vaddr, RMP_PG_SIZE_4K, validate); if (WARN(rc, "Failed to validate address 0x%lx ret %d", vaddr, rc)) sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE); vaddr = vaddr + PAGE_SIZE; } } static void __init early_set_pages_state(unsigned long paddr, unsigned int npages, enum psc_op op) { unsigned long paddr_end; u64 val; paddr = paddr & PAGE_MASK; paddr_end = paddr + (npages << PAGE_SHIFT); while (paddr < paddr_end) { /* * Use the MSR protocol because this function can be called before * the GHCB is established. */ sev_es_wr_ghcb_msr(GHCB_MSR_PSC_REQ_GFN(paddr >> PAGE_SHIFT, op)); VMGEXIT(); val = sev_es_rd_ghcb_msr(); if (WARN(GHCB_RESP_CODE(val) != GHCB_MSR_PSC_RESP, "Wrong PSC response code: 0x%x\n", (unsigned int)GHCB_RESP_CODE(val))) goto e_term; if (WARN(GHCB_MSR_PSC_RESP_VAL(val), "Failed to change page state to '%s' paddr 0x%lx error 0x%llx\n", op == SNP_PAGE_STATE_PRIVATE ? "private" : "shared", paddr, GHCB_MSR_PSC_RESP_VAL(val))) goto e_term; paddr = paddr + PAGE_SIZE; } return; e_term: sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC); } void __init early_snp_set_memory_private(unsigned long vaddr, unsigned long paddr, unsigned int npages) { /* * This can be invoked in early boot while running identity mapped, so * use an open coded check for SNP instead of using cc_platform_has(). * This eliminates worries about jump tables or checking boot_cpu_data * in the cc_platform_has() function. */ if (!(sev_status & MSR_AMD64_SEV_SNP_ENABLED)) return; /* * Ask the hypervisor to mark the memory pages as private in the RMP * table. */ early_set_pages_state(paddr, npages, SNP_PAGE_STATE_PRIVATE); /* Validate the memory pages after they've been added in the RMP table. */ pvalidate_pages(vaddr, npages, true); } void __init early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr, unsigned int npages) { /* * This can be invoked in early boot while running identity mapped, so * use an open coded check for SNP instead of using cc_platform_has(). * This eliminates worries about jump tables or checking boot_cpu_data * in the cc_platform_has() function. */ if (!(sev_status & MSR_AMD64_SEV_SNP_ENABLED)) return; /* Invalidate the memory pages before they are marked shared in the RMP table. */ pvalidate_pages(vaddr, npages, false); /* Ask hypervisor to mark the memory pages shared in the RMP table. */ early_set_pages_state(paddr, npages, SNP_PAGE_STATE_SHARED); } void __init snp_prep_memory(unsigned long paddr, unsigned int sz, enum psc_op op) { unsigned long vaddr, npages; vaddr = (unsigned long)__va(paddr); npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; if (op == SNP_PAGE_STATE_PRIVATE) early_snp_set_memory_private(vaddr, paddr, npages); else if (op == SNP_PAGE_STATE_SHARED) early_snp_set_memory_shared(vaddr, paddr, npages); else WARN(1, "invalid memory op %d\n", op); } static int vmgexit_psc(struct snp_psc_desc *desc) { int cur_entry, end_entry, ret = 0; struct snp_psc_desc *data; struct ghcb_state state; struct es_em_ctxt ctxt; unsigned long flags; struct ghcb *ghcb; /* * __sev_get_ghcb() needs to run with IRQs disabled because it is using * a per-CPU GHCB. */ local_irq_save(flags); ghcb = __sev_get_ghcb(&state); if (!ghcb) { ret = 1; goto out_unlock; } /* Copy the input desc into GHCB shared buffer */ data = (struct snp_psc_desc *)ghcb->shared_buffer; memcpy(ghcb->shared_buffer, desc, min_t(int, GHCB_SHARED_BUF_SIZE, sizeof(*desc))); /* * As per the GHCB specification, the hypervisor can resume the guest * before processing all the entries. Check whether all the entries * are processed. If not, then keep retrying. Note, the hypervisor * will update the data memory directly to indicate the status, so * reference the data->hdr everywhere. * * The strategy here is to wait for the hypervisor to change the page * state in the RMP table before guest accesses the memory pages. If the * page state change was not successful, then later memory access will * result in a crash. */ cur_entry = data->hdr.cur_entry; end_entry = data->hdr.end_entry; while (data->hdr.cur_entry <= data->hdr.end_entry) { ghcb_set_sw_scratch(ghcb, (u64)__pa(data)); /* This will advance the shared buffer data points to. */ ret = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_PSC, 0, 0); /* * Page State Change VMGEXIT can pass error code through * exit_info_2. */ if (WARN(ret || ghcb->save.sw_exit_info_2, "SNP: PSC failed ret=%d exit_info_2=%llx\n", ret, ghcb->save.sw_exit_info_2)) { ret = 1; goto out; } /* Verify that reserved bit is not set */ if (WARN(data->hdr.reserved, "Reserved bit is set in the PSC header\n")) { ret = 1; goto out; } /* * Sanity check that entry processing is not going backwards. * This will happen only if hypervisor is tricking us. */ if (WARN(data->hdr.end_entry > end_entry || cur_entry > data->hdr.cur_entry, "SNP: PSC processing going backward, end_entry %d (got %d) cur_entry %d (got %d)\n", end_entry, data->hdr.end_entry, cur_entry, data->hdr.cur_entry)) { ret = 1; goto out; } } out: __sev_put_ghcb(&state); out_unlock: local_irq_restore(flags); return ret; } static void __set_pages_state(struct snp_psc_desc *data, unsigned long vaddr, unsigned long vaddr_end, int op) { struct psc_hdr *hdr; struct psc_entry *e; unsigned long pfn; int i; hdr = &data->hdr; e = data->entries; memset(data, 0, sizeof(*data)); i = 0; while (vaddr < vaddr_end) { if (is_vmalloc_addr((void *)vaddr)) pfn = vmalloc_to_pfn((void *)vaddr); else pfn = __pa(vaddr) >> PAGE_SHIFT; e->gfn = pfn; e->operation = op; hdr->end_entry = i; /* * Current SNP implementation doesn't keep track of the RMP page * size so use 4K for simplicity. */ e->pagesize = RMP_PG_SIZE_4K; vaddr = vaddr + PAGE_SIZE; e++; i++; } if (vmgexit_psc(data)) sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC); } static void set_pages_state(unsigned long vaddr, unsigned int npages, int op) { unsigned long vaddr_end, next_vaddr; struct snp_psc_desc *desc; desc = kmalloc(sizeof(*desc), GFP_KERNEL_ACCOUNT); if (!desc) panic("SNP: failed to allocate memory for PSC descriptor\n"); vaddr = vaddr & PAGE_MASK; vaddr_end = vaddr + (npages << PAGE_SHIFT); while (vaddr < vaddr_end) { /* Calculate the last vaddr that fits in one struct snp_psc_desc. */ next_vaddr = min_t(unsigned long, vaddr_end, (VMGEXIT_PSC_MAX_ENTRY * PAGE_SIZE) + vaddr); __set_pages_state(desc, vaddr, next_vaddr, op); vaddr = next_vaddr; } kfree(desc); } void snp_set_memory_shared(unsigned long vaddr, unsigned int npages) { if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) return; pvalidate_pages(vaddr, npages, false); set_pages_state(vaddr, npages, SNP_PAGE_STATE_SHARED); } void snp_set_memory_private(unsigned long vaddr, unsigned int npages) { if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) return; set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE); pvalidate_pages(vaddr, npages, true); } static int snp_set_vmsa(void *va, bool vmsa) { u64 attrs; /* * Running at VMPL0 allows the kernel to change the VMSA bit for a page * using the RMPADJUST instruction. However, for the instruction to * succeed it must target the permissions of a lesser privileged * (higher numbered) VMPL level, so use VMPL1 (refer to the RMPADJUST * instruction in the AMD64 APM Volume 3). */ attrs = 1; if (vmsa) attrs |= RMPADJUST_VMSA_PAGE_BIT; return rmpadjust((unsigned long)va, RMP_PG_SIZE_4K, attrs); } #define __ATTR_BASE (SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK) #define INIT_CS_ATTRIBS (__ATTR_BASE | SVM_SELECTOR_READ_MASK | SVM_SELECTOR_CODE_MASK) #define INIT_DS_ATTRIBS (__ATTR_BASE | SVM_SELECTOR_WRITE_MASK) #define INIT_LDTR_ATTRIBS (SVM_SELECTOR_P_MASK | 2) #define INIT_TR_ATTRIBS (SVM_SELECTOR_P_MASK | 3) static void *snp_alloc_vmsa_page(void) { struct page *p; /* * Allocate VMSA page to work around the SNP erratum where the CPU will * incorrectly signal an RMP violation #PF if a large page (2MB or 1GB) * collides with the RMP entry of VMSA page. The recommended workaround * is to not use a large page. * * Allocate an 8k page which is also 8k-aligned. */ p = alloc_pages(GFP_KERNEL_ACCOUNT | __GFP_ZERO, 1); if (!p) return NULL; split_page(p, 1); /* Free the first 4k. This page may be 2M/1G aligned and cannot be used. */ __free_page(p); return page_address(p + 1); } static void snp_cleanup_vmsa(struct sev_es_save_area *vmsa) { int err; err = snp_set_vmsa(vmsa, false); if (err) pr_err("clear VMSA page failed (%u), leaking page\n", err); else free_page((unsigned long)vmsa); } static int wakeup_cpu_via_vmgexit(int apic_id, unsigned long start_ip) { struct sev_es_save_area *cur_vmsa, *vmsa; struct ghcb_state state; unsigned long flags; struct ghcb *ghcb; u8 sipi_vector; int cpu, ret; u64 cr4; /* * The hypervisor SNP feature support check has happened earlier, just check * the AP_CREATION one here. */ if (!(sev_hv_features & GHCB_HV_FT_SNP_AP_CREATION)) return -EOPNOTSUPP; /* * Verify the desired start IP against the known trampoline start IP * to catch any future new trampolines that may be introduced that * would require a new protected guest entry point. */ if (WARN_ONCE(start_ip != real_mode_header->trampoline_start, "Unsupported SNP start_ip: %lx\n", start_ip)) return -EINVAL; /* Override start_ip with known protected guest start IP */ start_ip = real_mode_header->sev_es_trampoline_start; /* Find the logical CPU for the APIC ID */ for_each_present_cpu(cpu) { if (arch_match_cpu_phys_id(cpu, apic_id)) break; } if (cpu >= nr_cpu_ids) return -EINVAL; cur_vmsa = per_cpu(sev_vmsa, cpu); /* * A new VMSA is created each time because there is no guarantee that * the current VMSA is the kernels or that the vCPU is not running. If * an attempt was done to use the current VMSA with a running vCPU, a * #VMEXIT of that vCPU would wipe out all of the settings being done * here. */ vmsa = (struct sev_es_save_area *)snp_alloc_vmsa_page(); if (!vmsa) return -ENOMEM; /* CR4 should maintain the MCE value */ cr4 = native_read_cr4() & X86_CR4_MCE; /* Set the CS value based on the start_ip converted to a SIPI vector */ sipi_vector = (start_ip >> 12); vmsa->cs.base = sipi_vector << 12; vmsa->cs.limit = AP_INIT_CS_LIMIT; vmsa->cs.attrib = INIT_CS_ATTRIBS; vmsa->cs.selector = sipi_vector << 8; /* Set the RIP value based on start_ip */ vmsa->rip = start_ip & 0xfff; /* Set AP INIT defaults as documented in the APM */ vmsa->ds.limit = AP_INIT_DS_LIMIT; vmsa->ds.attrib = INIT_DS_ATTRIBS; vmsa->es = vmsa->ds; vmsa->fs = vmsa->ds; vmsa->gs = vmsa->ds; vmsa->ss = vmsa->ds; vmsa->gdtr.limit = AP_INIT_GDTR_LIMIT; vmsa->ldtr.limit = AP_INIT_LDTR_LIMIT; vmsa->ldtr.attrib = INIT_LDTR_ATTRIBS; vmsa->idtr.limit = AP_INIT_IDTR_LIMIT; vmsa->tr.limit = AP_INIT_TR_LIMIT; vmsa->tr.attrib = INIT_TR_ATTRIBS; vmsa->cr4 = cr4; vmsa->cr0 = AP_INIT_CR0_DEFAULT; vmsa->dr7 = DR7_RESET_VALUE; vmsa->dr6 = AP_INIT_DR6_DEFAULT; vmsa->rflags = AP_INIT_RFLAGS_DEFAULT; vmsa->g_pat = AP_INIT_GPAT_DEFAULT; vmsa->xcr0 = AP_INIT_XCR0_DEFAULT; vmsa->mxcsr = AP_INIT_MXCSR_DEFAULT; vmsa->x87_ftw = AP_INIT_X87_FTW_DEFAULT; vmsa->x87_fcw = AP_INIT_X87_FCW_DEFAULT; /* SVME must be set. */ vmsa->efer = EFER_SVME; /* * Set the SNP-specific fields for this VMSA: * VMPL level * SEV_FEATURES (matches the SEV STATUS MSR right shifted 2 bits) */ vmsa->vmpl = 0; vmsa->sev_features = sev_status >> 2; /* Switch the page over to a VMSA page now that it is initialized */ ret = snp_set_vmsa(vmsa, true); if (ret) { pr_err("set VMSA page failed (%u)\n", ret); free_page((unsigned long)vmsa); return -EINVAL; } /* Issue VMGEXIT AP Creation NAE event */ local_irq_save(flags); ghcb = __sev_get_ghcb(&state); vc_ghcb_invalidate(ghcb); ghcb_set_rax(ghcb, vmsa->sev_features); ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_CREATION); ghcb_set_sw_exit_info_1(ghcb, ((u64)apic_id << 32) | SVM_VMGEXIT_AP_CREATE); ghcb_set_sw_exit_info_2(ghcb, __pa(vmsa)); sev_es_wr_ghcb_msr(__pa(ghcb)); VMGEXIT(); if (!ghcb_sw_exit_info_1_is_valid(ghcb) || lower_32_bits(ghcb->save.sw_exit_info_1)) { pr_err("SNP AP Creation error\n"); ret = -EINVAL; } __sev_put_ghcb(&state); local_irq_restore(flags); /* Perform cleanup if there was an error */ if (ret) { snp_cleanup_vmsa(vmsa); vmsa = NULL; } /* Free up any previous VMSA page */ if (cur_vmsa) snp_cleanup_vmsa(cur_vmsa); /* Record the current VMSA page */ per_cpu(sev_vmsa, cpu) = vmsa; return ret; } void snp_set_wakeup_secondary_cpu(void) { if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) return; /* * Always set this override if SNP is enabled. This makes it the * required method to start APs under SNP. If the hypervisor does * not support AP creation, then no APs will be started. */ apic->wakeup_secondary_cpu = wakeup_cpu_via_vmgexit; } int __init sev_es_setup_ap_jump_table(struct real_mode_header *rmh) { u16 startup_cs, startup_ip; phys_addr_t jump_table_pa; u64 jump_table_addr; u16 __iomem *jump_table; jump_table_addr = get_jump_table_addr(); /* On UP guests there is no jump table so this is not a failure */ if (!jump_table_addr) return 0; /* Check if AP Jump Table is page-aligned */ if (jump_table_addr & ~PAGE_MASK) return -EINVAL; jump_table_pa = jump_table_addr & PAGE_MASK; startup_cs = (u16)(rmh->trampoline_start >> 4); startup_ip = (u16)(rmh->sev_es_trampoline_start - rmh->trampoline_start); jump_table = ioremap_encrypted(jump_table_pa, PAGE_SIZE); if (!jump_table) return -EIO; writew(startup_ip, &jump_table[0]); writew(startup_cs, &jump_table[1]); iounmap(jump_table); return 0; } /* * This is needed by the OVMF UEFI firmware which will use whatever it finds in * the GHCB MSR as its GHCB to talk to the hypervisor. So make sure the per-cpu * runtime GHCBs used by the kernel are also mapped in the EFI page-table. */ int __init sev_es_efi_map_ghcbs(pgd_t *pgd) { struct sev_es_runtime_data *data; unsigned long address, pflags; int cpu; u64 pfn; if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) return 0; pflags = _PAGE_NX | _PAGE_RW; for_each_possible_cpu(cpu) { data = per_cpu(runtime_data, cpu); address = __pa(&data->ghcb_page); pfn = address >> PAGE_SHIFT; if (kernel_map_pages_in_pgd(pgd, pfn, address, 1, pflags)) return 1; } return 0; } static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { struct pt_regs *regs = ctxt->regs; enum es_result ret; u64 exit_info_1; /* Is it a WRMSR? */ exit_info_1 = (ctxt->insn.opcode.bytes[1] == 0x30) ? 1 : 0; ghcb_set_rcx(ghcb, regs->cx); if (exit_info_1) { ghcb_set_rax(ghcb, regs->ax); ghcb_set_rdx(ghcb, regs->dx); } ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_MSR, exit_info_1, 0); if ((ret == ES_OK) && (!exit_info_1)) { regs->ax = ghcb->save.rax; regs->dx = ghcb->save.rdx; } return ret; } static void snp_register_per_cpu_ghcb(void) { struct sev_es_runtime_data *data; struct ghcb *ghcb; data = this_cpu_read(runtime_data); ghcb = &data->ghcb_page; snp_register_ghcb_early(__pa(ghcb)); } void setup_ghcb(void) { if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) return; /* First make sure the hypervisor talks a supported protocol. */ if (!sev_es_negotiate_protocol()) sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ); /* * Check whether the runtime #VC exception handler is active. It uses * the per-CPU GHCB page which is set up by sev_es_init_vc_handling(). * * If SNP is active, register the per-CPU GHCB page so that the runtime * exception handler can use it. */ if (initial_vc_handler == (unsigned long)kernel_exc_vmm_communication) { if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) snp_register_per_cpu_ghcb(); return; } /* * Clear the boot_ghcb. The first exception comes in before the bss * section is cleared. */ memset(&boot_ghcb_page, 0, PAGE_SIZE); /* Alright - Make the boot-ghcb public */ boot_ghcb = &boot_ghcb_page; /* SNP guest requires that GHCB GPA must be registered. */ if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) snp_register_ghcb_early(__pa(&boot_ghcb_page)); } #ifdef CONFIG_HOTPLUG_CPU static void sev_es_ap_hlt_loop(void) { struct ghcb_state state; struct ghcb *ghcb; ghcb = __sev_get_ghcb(&state); while (true) { vc_ghcb_invalidate(ghcb); ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_HLT_LOOP); ghcb_set_sw_exit_info_1(ghcb, 0); ghcb_set_sw_exit_info_2(ghcb, 0); sev_es_wr_ghcb_msr(__pa(ghcb)); VMGEXIT(); /* Wakeup signal? */ if (ghcb_sw_exit_info_2_is_valid(ghcb) && ghcb->save.sw_exit_info_2) break; } __sev_put_ghcb(&state); } /* * Play_dead handler when running under SEV-ES. This is needed because * the hypervisor can't deliver an SIPI request to restart the AP. * Instead the kernel has to issue a VMGEXIT to halt the VCPU until the * hypervisor wakes it up again. */ static void sev_es_play_dead(void) { play_dead_common(); /* IRQs now disabled */ sev_es_ap_hlt_loop(); /* * If we get here, the VCPU was woken up again. Jump to CPU * startup code to get it back online. */ start_cpu0(); } #else /* CONFIG_HOTPLUG_CPU */ #define sev_es_play_dead native_play_dead #endif /* CONFIG_HOTPLUG_CPU */ #ifdef CONFIG_SMP static void __init sev_es_setup_play_dead(void) { smp_ops.play_dead = sev_es_play_dead; } #else static inline void sev_es_setup_play_dead(void) { } #endif static void __init alloc_runtime_data(int cpu) { struct sev_es_runtime_data *data; data = memblock_alloc(sizeof(*data), PAGE_SIZE); if (!data) panic("Can't allocate SEV-ES runtime data"); per_cpu(runtime_data, cpu) = data; } static void __init init_ghcb(int cpu) { struct sev_es_runtime_data *data; int err; data = per_cpu(runtime_data, cpu); err = early_set_memory_decrypted((unsigned long)&data->ghcb_page, sizeof(data->ghcb_page)); if (err) panic("Can't map GHCBs unencrypted"); memset(&data->ghcb_page, 0, sizeof(data->ghcb_page)); data->ghcb_active = false; data->backup_ghcb_active = false; } void __init sev_es_init_vc_handling(void) { int cpu; BUILD_BUG_ON(offsetof(struct sev_es_runtime_data, ghcb_page) % PAGE_SIZE); if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) return; if (!sev_es_check_cpu_features()) panic("SEV-ES CPU Features missing"); /* * SNP is supported in v2 of the GHCB spec which mandates support for HV * features. */ if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) { sev_hv_features = get_hv_features(); if (!(sev_hv_features & GHCB_HV_FT_SNP)) sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED); } /* Enable SEV-ES special handling */ static_branch_enable(&sev_es_enable_key); /* Initialize per-cpu GHCB pages */ for_each_possible_cpu(cpu) { alloc_runtime_data(cpu); init_ghcb(cpu); } sev_es_setup_play_dead(); /* Secondary CPUs use the runtime #VC handler */ initial_vc_handler = (unsigned long)kernel_exc_vmm_communication; } static void __init vc_early_forward_exception(struct es_em_ctxt *ctxt) { int trapnr = ctxt->fi.vector; if (trapnr == X86_TRAP_PF) native_write_cr2(ctxt->fi.cr2); ctxt->regs->orig_ax = ctxt->fi.error_code; do_early_exception(ctxt->regs, trapnr); } static long *vc_insn_get_rm(struct es_em_ctxt *ctxt) { long *reg_array; int offset; reg_array = (long *)ctxt->regs; offset = insn_get_modrm_rm_off(&ctxt->insn, ctxt->regs); if (offset < 0) return NULL; offset /= sizeof(long); return reg_array + offset; } static enum es_result vc_do_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt, unsigned int bytes, bool read) { u64 exit_code, exit_info_1, exit_info_2; unsigned long ghcb_pa = __pa(ghcb); enum es_result res; phys_addr_t paddr; void __user *ref; ref = insn_get_addr_ref(&ctxt->insn, ctxt->regs); if (ref == (void __user *)-1L) return ES_UNSUPPORTED; exit_code = read ? SVM_VMGEXIT_MMIO_READ : SVM_VMGEXIT_MMIO_WRITE; res = vc_slow_virt_to_phys(ghcb, ctxt, (unsigned long)ref, &paddr); if (res != ES_OK) { if (res == ES_EXCEPTION && !read) ctxt->fi.error_code |= X86_PF_WRITE; return res; } exit_info_1 = paddr; /* Can never be greater than 8 */ exit_info_2 = bytes; ghcb_set_sw_scratch(ghcb, ghcb_pa + offsetof(struct ghcb, shared_buffer)); return sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, exit_info_1, exit_info_2); } /* * The MOVS instruction has two memory operands, which raises the * problem that it is not known whether the access to the source or the * destination caused the #VC exception (and hence whether an MMIO read * or write operation needs to be emulated). * * Instead of playing games with walking page-tables and trying to guess * whether the source or destination is an MMIO range, split the move * into two operations, a read and a write with only one memory operand. * This will cause a nested #VC exception on the MMIO address which can * then be handled. * * This implementation has the benefit that it also supports MOVS where * source _and_ destination are MMIO regions. * * It will slow MOVS on MMIO down a lot, but in SEV-ES guests it is a * rare operation. If it turns out to be a performance problem the split * operations can be moved to memcpy_fromio() and memcpy_toio(). */ static enum es_result vc_handle_mmio_movs(struct es_em_ctxt *ctxt, unsigned int bytes) { unsigned long ds_base, es_base; unsigned char *src, *dst; unsigned char buffer[8]; enum es_result ret; bool rep; int off; ds_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_DS); es_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_ES); if (ds_base == -1L || es_base == -1L) { ctxt->fi.vector = X86_TRAP_GP; ctxt->fi.error_code = 0; return ES_EXCEPTION; } src = ds_base + (unsigned char *)ctxt->regs->si; dst = es_base + (unsigned char *)ctxt->regs->di; ret = vc_read_mem(ctxt, src, buffer, bytes); if (ret != ES_OK) return ret; ret = vc_write_mem(ctxt, dst, buffer, bytes); if (ret != ES_OK) return ret; if (ctxt->regs->flags & X86_EFLAGS_DF) off = -bytes; else off = bytes; ctxt->regs->si += off; ctxt->regs->di += off; rep = insn_has_rep_prefix(&ctxt->insn); if (rep) ctxt->regs->cx -= 1; if (!rep || ctxt->regs->cx == 0) return ES_OK; else return ES_RETRY; } static enum es_result vc_handle_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { struct insn *insn = &ctxt->insn; unsigned int bytes = 0; enum mmio_type mmio; enum es_result ret; u8 sign_byte; long *reg_data; mmio = insn_decode_mmio(insn, &bytes); if (mmio == MMIO_DECODE_FAILED) return ES_DECODE_FAILED; if (mmio != MMIO_WRITE_IMM && mmio != MMIO_MOVS) { reg_data = insn_get_modrm_reg_ptr(insn, ctxt->regs); if (!reg_data) return ES_DECODE_FAILED; } switch (mmio) { case MMIO_WRITE: memcpy(ghcb->shared_buffer, reg_data, bytes); ret = vc_do_mmio(ghcb, ctxt, bytes, false); break; case MMIO_WRITE_IMM: memcpy(ghcb->shared_buffer, insn->immediate1.bytes, bytes); ret = vc_do_mmio(ghcb, ctxt, bytes, false); break; case MMIO_READ: ret = vc_do_mmio(ghcb, ctxt, bytes, true); if (ret) break; /* Zero-extend for 32-bit operation */ if (bytes == 4) *reg_data = 0; memcpy(reg_data, ghcb->shared_buffer, bytes); break; case MMIO_READ_ZERO_EXTEND: ret = vc_do_mmio(ghcb, ctxt, bytes, true); if (ret) break; /* Zero extend based on operand size */ memset(reg_data, 0, insn->opnd_bytes); memcpy(reg_data, ghcb->shared_buffer, bytes); break; case MMIO_READ_SIGN_EXTEND: ret = vc_do_mmio(ghcb, ctxt, bytes, true); if (ret) break; if (bytes == 1) { u8 *val = (u8 *)ghcb->shared_buffer; sign_byte = (*val & 0x80) ? 0xff : 0x00; } else { u16 *val = (u16 *)ghcb->shared_buffer; sign_byte = (*val & 0x8000) ? 0xff : 0x00; } /* Sign extend based on operand size */ memset(reg_data, sign_byte, insn->opnd_bytes); memcpy(reg_data, ghcb->shared_buffer, bytes); break; case MMIO_MOVS: ret = vc_handle_mmio_movs(ctxt, bytes); break; default: ret = ES_UNSUPPORTED; break; } return ret; } static enum es_result vc_handle_dr7_write(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { struct sev_es_runtime_data *data = this_cpu_read(runtime_data); long val, *reg = vc_insn_get_rm(ctxt); enum es_result ret; if (!reg) return ES_DECODE_FAILED; val = *reg; /* Upper 32 bits must be written as zeroes */ if (val >> 32) { ctxt->fi.vector = X86_TRAP_GP; ctxt->fi.error_code = 0; return ES_EXCEPTION; } /* Clear out other reserved bits and set bit 10 */ val = (val & 0xffff23ffL) | BIT(10); /* Early non-zero writes to DR7 are not supported */ if (!data && (val & ~DR7_RESET_VALUE)) return ES_UNSUPPORTED; /* Using a value of 0 for ExitInfo1 means RAX holds the value */ ghcb_set_rax(ghcb, val); ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_WRITE_DR7, 0, 0); if (ret != ES_OK) return ret; if (data) data->dr7 = val; return ES_OK; } static enum es_result vc_handle_dr7_read(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { struct sev_es_runtime_data *data = this_cpu_read(runtime_data); long *reg = vc_insn_get_rm(ctxt); if (!reg) return ES_DECODE_FAILED; if (data) *reg = data->dr7; else *reg = DR7_RESET_VALUE; return ES_OK; } static enum es_result vc_handle_wbinvd(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { return sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_WBINVD, 0, 0); } static enum es_result vc_handle_rdpmc(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { enum es_result ret; ghcb_set_rcx(ghcb, ctxt->regs->cx); ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_RDPMC, 0, 0); if (ret != ES_OK) return ret; if (!(ghcb_rax_is_valid(ghcb) && ghcb_rdx_is_valid(ghcb))) return ES_VMM_ERROR; ctxt->regs->ax = ghcb->save.rax; ctxt->regs->dx = ghcb->save.rdx; return ES_OK; } static enum es_result vc_handle_monitor(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { /* * Treat it as a NOP and do not leak a physical address to the * hypervisor. */ return ES_OK; } static enum es_result vc_handle_mwait(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { /* Treat the same as MONITOR/MONITORX */ return ES_OK; } static enum es_result vc_handle_vmmcall(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { enum es_result ret; ghcb_set_rax(ghcb, ctxt->regs->ax); ghcb_set_cpl(ghcb, user_mode(ctxt->regs) ? 3 : 0); if (x86_platform.hyper.sev_es_hcall_prepare) x86_platform.hyper.sev_es_hcall_prepare(ghcb, ctxt->regs); ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_VMMCALL, 0, 0); if (ret != ES_OK) return ret; if (!ghcb_rax_is_valid(ghcb)) return ES_VMM_ERROR; ctxt->regs->ax = ghcb->save.rax; /* * Call sev_es_hcall_finish() after regs->ax is already set. * This allows the hypervisor handler to overwrite it again if * necessary. */ if (x86_platform.hyper.sev_es_hcall_finish && !x86_platform.hyper.sev_es_hcall_finish(ghcb, ctxt->regs)) return ES_VMM_ERROR; return ES_OK; } static enum es_result vc_handle_trap_ac(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { /* * Calling ecx_alignment_check() directly does not work, because it * enables IRQs and the GHCB is active. Forward the exception and call * it later from vc_forward_exception(). */ ctxt->fi.vector = X86_TRAP_AC; ctxt->fi.error_code = 0; return ES_EXCEPTION; } static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt, struct ghcb *ghcb, unsigned long exit_code) { enum es_result result; switch (exit_code) { case SVM_EXIT_READ_DR7: result = vc_handle_dr7_read(ghcb, ctxt); break; case SVM_EXIT_WRITE_DR7: result = vc_handle_dr7_write(ghcb, ctxt); break; case SVM_EXIT_EXCP_BASE + X86_TRAP_AC: result = vc_handle_trap_ac(ghcb, ctxt); break; case SVM_EXIT_RDTSC: case SVM_EXIT_RDTSCP: result = vc_handle_rdtsc(ghcb, ctxt, exit_code); break; case SVM_EXIT_RDPMC: result = vc_handle_rdpmc(ghcb, ctxt); break; case SVM_EXIT_INVD: pr_err_ratelimited("#VC exception for INVD??? Seriously???\n"); result = ES_UNSUPPORTED; break; case SVM_EXIT_CPUID: result = vc_handle_cpuid(ghcb, ctxt); break; case SVM_EXIT_IOIO: result = vc_handle_ioio(ghcb, ctxt); break; case SVM_EXIT_MSR: result = vc_handle_msr(ghcb, ctxt); break; case SVM_EXIT_VMMCALL: result = vc_handle_vmmcall(ghcb, ctxt); break; case SVM_EXIT_WBINVD: result = vc_handle_wbinvd(ghcb, ctxt); break; case SVM_EXIT_MONITOR: result = vc_handle_monitor(ghcb, ctxt); break; case SVM_EXIT_MWAIT: result = vc_handle_mwait(ghcb, ctxt); break; case SVM_EXIT_NPF: result = vc_handle_mmio(ghcb, ctxt); break; default: /* * Unexpected #VC exception */ result = ES_UNSUPPORTED; } return result; } static __always_inline void vc_forward_exception(struct es_em_ctxt *ctxt) { long error_code = ctxt->fi.error_code; int trapnr = ctxt->fi.vector; ctxt->regs->orig_ax = ctxt->fi.error_code; switch (trapnr) { case X86_TRAP_GP: exc_general_protection(ctxt->regs, error_code); break; case X86_TRAP_UD: exc_invalid_op(ctxt->regs); break; case X86_TRAP_PF: write_cr2(ctxt->fi.cr2); exc_page_fault(ctxt->regs, error_code); break; case X86_TRAP_AC: exc_alignment_check(ctxt->regs, error_code); break; default: pr_emerg("Unsupported exception in #VC instruction emulation - can't continue\n"); BUG(); } } static __always_inline bool is_vc2_stack(unsigned long sp) { return (sp >= __this_cpu_ist_bottom_va(VC2) && sp < __this_cpu_ist_top_va(VC2)); } static __always_inline bool vc_from_invalid_context(struct pt_regs *regs) { unsigned long sp, prev_sp; sp = (unsigned long)regs; prev_sp = regs->sp; /* * If the code was already executing on the VC2 stack when the #VC * happened, let it proceed to the normal handling routine. This way the * code executing on the VC2 stack can cause #VC exceptions to get handled. */ return is_vc2_stack(sp) && !is_vc2_stack(prev_sp); } static bool vc_raw_handle_exception(struct pt_regs *regs, unsigned long error_code) { struct ghcb_state state; struct es_em_ctxt ctxt; enum es_result result; struct ghcb *ghcb; bool ret = true; ghcb = __sev_get_ghcb(&state); vc_ghcb_invalidate(ghcb); result = vc_init_em_ctxt(&ctxt, regs, error_code); if (result == ES_OK) result = vc_handle_exitcode(&ctxt, ghcb, error_code); __sev_put_ghcb(&state); /* Done - now check the result */ switch (result) { case ES_OK: vc_finish_insn(&ctxt); break; case ES_UNSUPPORTED: pr_err_ratelimited("Unsupported exit-code 0x%02lx in #VC exception (IP: 0x%lx)\n", error_code, regs->ip); ret = false; break; case ES_VMM_ERROR: pr_err_ratelimited("Failure in communication with VMM (exit-code 0x%02lx IP: 0x%lx)\n", error_code, regs->ip); ret = false; break; case ES_DECODE_FAILED: pr_err_ratelimited("Failed to decode instruction (exit-code 0x%02lx IP: 0x%lx)\n", error_code, regs->ip); ret = false; break; case ES_EXCEPTION: vc_forward_exception(&ctxt); break; case ES_RETRY: /* Nothing to do */ break; default: pr_emerg("Unknown result in %s():%d\n", __func__, result); /* * Emulating the instruction which caused the #VC exception * failed - can't continue so print debug information */ BUG(); } return ret; } static __always_inline bool vc_is_db(unsigned long error_code) { return error_code == SVM_EXIT_EXCP_BASE + X86_TRAP_DB; } /* * Runtime #VC exception handler when raised from kernel mode. Runs in NMI mode * and will panic when an error happens. */ DEFINE_IDTENTRY_VC_KERNEL(exc_vmm_communication) { irqentry_state_t irq_state; /* * With the current implementation it is always possible to switch to a * safe stack because #VC exceptions only happen at known places, like * intercepted instructions or accesses to MMIO areas/IO ports. They can * also happen with code instrumentation when the hypervisor intercepts * #DB, but the critical paths are forbidden to be instrumented, so #DB * exceptions currently also only happen in safe places. * * But keep this here in case the noinstr annotations are violated due * to bug elsewhere. */ if (unlikely(vc_from_invalid_context(regs))) { instrumentation_begin(); panic("Can't handle #VC exception from unsupported context\n"); instrumentation_end(); } /* * Handle #DB before calling into !noinstr code to avoid recursive #DB. */ if (vc_is_db(error_code)) { exc_debug(regs); return; } irq_state = irqentry_nmi_enter(regs); instrumentation_begin(); if (!vc_raw_handle_exception(regs, error_code)) { /* Show some debug info */ show_regs(regs); /* Ask hypervisor to sev_es_terminate */ sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ); /* If that fails and we get here - just panic */ panic("Returned from Terminate-Request to Hypervisor\n"); } instrumentation_end(); irqentry_nmi_exit(regs, irq_state); } /* * Runtime #VC exception handler when raised from user mode. Runs in IRQ mode * and will kill the current task with SIGBUS when an error happens. */ DEFINE_IDTENTRY_VC_USER(exc_vmm_communication) { /* * Handle #DB before calling into !noinstr code to avoid recursive #DB. */ if (vc_is_db(error_code)) { noist_exc_debug(regs); return; } irqentry_enter_from_user_mode(regs); instrumentation_begin(); if (!vc_raw_handle_exception(regs, error_code)) { /* * Do not kill the machine if user-space triggered the * exception. Send SIGBUS instead and let user-space deal with * it. */ force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)0); } instrumentation_end(); irqentry_exit_to_user_mode(regs); } bool __init handle_vc_boot_ghcb(struct pt_regs *regs) { unsigned long exit_code = regs->orig_ax; struct es_em_ctxt ctxt; enum es_result result; vc_ghcb_invalidate(boot_ghcb); result = vc_init_em_ctxt(&ctxt, regs, exit_code); if (result == ES_OK) result = vc_handle_exitcode(&ctxt, boot_ghcb, exit_code); /* Done - now check the result */ switch (result) { case ES_OK: vc_finish_insn(&ctxt); break; case ES_UNSUPPORTED: early_printk("PANIC: Unsupported exit-code 0x%02lx in early #VC exception (IP: 0x%lx)\n", exit_code, regs->ip); goto fail; case ES_VMM_ERROR: early_printk("PANIC: Failure in communication with VMM (exit-code 0x%02lx IP: 0x%lx)\n", exit_code, regs->ip); goto fail; case ES_DECODE_FAILED: early_printk("PANIC: Failed to decode instruction (exit-code 0x%02lx IP: 0x%lx)\n", exit_code, regs->ip); goto fail; case ES_EXCEPTION: vc_early_forward_exception(&ctxt); break; case ES_RETRY: /* Nothing to do */ break; default: BUG(); } return true; fail: show_regs(regs); sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ); } /* * Initial set up of SNP relies on information provided by the * Confidential Computing blob, which can be passed to the kernel * in the following ways, depending on how it is booted: * * - when booted via the boot/decompress kernel: * - via boot_params * * - when booted directly by firmware/bootloader (e.g. CONFIG_PVH): * - via a setup_data entry, as defined by the Linux Boot Protocol * * Scan for the blob in that order. */ static __init struct cc_blob_sev_info *find_cc_blob(struct boot_params *bp) { struct cc_blob_sev_info *cc_info; /* Boot kernel would have passed the CC blob via boot_params. */ if (bp->cc_blob_address) { cc_info = (struct cc_blob_sev_info *)(unsigned long)bp->cc_blob_address; goto found_cc_info; } /* * If kernel was booted directly, without the use of the * boot/decompression kernel, the CC blob may have been passed via * setup_data instead. */ cc_info = find_cc_blob_setup_data(bp); if (!cc_info) return NULL; found_cc_info: if (cc_info->magic != CC_BLOB_SEV_HDR_MAGIC) snp_abort(); return cc_info; } bool __init snp_init(struct boot_params *bp) { struct cc_blob_sev_info *cc_info; if (!bp) return false; cc_info = find_cc_blob(bp); if (!cc_info) return false; setup_cpuid_table(cc_info); /* * The CC blob will be used later to access the secrets page. Cache * it here like the boot kernel does. */ bp->cc_blob_address = (u32)(unsigned long)cc_info; return true; } void __init __noreturn snp_abort(void) { sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED); } static void dump_cpuid_table(void) { const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table(); int i = 0; pr_info("count=%d reserved=0x%x reserved2=0x%llx\n", cpuid_table->count, cpuid_table->__reserved1, cpuid_table->__reserved2); for (i = 0; i < SNP_CPUID_COUNT_MAX; i++) { const struct snp_cpuid_fn *fn = &cpuid_table->fn[i]; pr_info("index=%3d fn=0x%08x subfn=0x%08x: eax=0x%08x ebx=0x%08x ecx=0x%08x edx=0x%08x xcr0_in=0x%016llx xss_in=0x%016llx reserved=0x%016llx\n", i, fn->eax_in, fn->ecx_in, fn->eax, fn->ebx, fn->ecx, fn->edx, fn->xcr0_in, fn->xss_in, fn->__reserved); } } /* * It is useful from an auditing/testing perspective to provide an easy way * for the guest owner to know that the CPUID table has been initialized as * expected, but that initialization happens too early in boot to print any * sort of indicator, and there's not really any other good place to do it, * so do it here. */ static int __init report_cpuid_table(void) { const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table(); if (!cpuid_table->count) return 0; pr_info("Using SNP CPUID table, %d entries present.\n", cpuid_table->count); if (sev_cfg.debug) dump_cpuid_table(); return 0; } arch_initcall(report_cpuid_table); static int __init init_sev_config(char *str) { char *s; while ((s = strsep(&str, ","))) { if (!strcmp(s, "debug")) { sev_cfg.debug = true; continue; } pr_info("SEV command-line option '%s' was not recognized\n", s); } return 1; } __setup("sev=", init_sev_config); int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err) { struct ghcb_state state; struct es_em_ctxt ctxt; unsigned long flags; struct ghcb *ghcb; int ret; if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) return -ENODEV; if (!fw_err) return -EINVAL; /* * __sev_get_ghcb() needs to run with IRQs disabled because it is using * a per-CPU GHCB. */ local_irq_save(flags); ghcb = __sev_get_ghcb(&state); if (!ghcb) { ret = -EIO; goto e_restore_irq; } vc_ghcb_invalidate(ghcb); if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) { ghcb_set_rax(ghcb, input->data_gpa); ghcb_set_rbx(ghcb, input->data_npages); } ret = sev_es_ghcb_hv_call(ghcb, &ctxt, exit_code, input->req_gpa, input->resp_gpa); if (ret) goto e_put; if (ghcb->save.sw_exit_info_2) { /* Number of expected pages are returned in RBX */ if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST && ghcb->save.sw_exit_info_2 == SNP_GUEST_REQ_INVALID_LEN) input->data_npages = ghcb_get_rbx(ghcb); *fw_err = ghcb->save.sw_exit_info_2; ret = -EIO; } e_put: __sev_put_ghcb(&state); e_restore_irq: local_irq_restore(flags); return ret; } EXPORT_SYMBOL_GPL(snp_issue_guest_request); static struct platform_device sev_guest_device = { .name = "sev-guest", .id = -1, }; static int __init snp_init_platform_device(void) { struct sev_guest_platform_data data; u64 gpa; if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) return -ENODEV; gpa = get_secrets_page(); if (!gpa) return -ENODEV; data.secrets_gpa = gpa; if (platform_device_add_data(&sev_guest_device, &data, sizeof(data))) return -ENODEV; if (platform_device_register(&sev_guest_device)) return -ENODEV; pr_info("SNP guest platform device initialized.\n"); return 0; } device_initcall(snp_init_platform_device);
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