// SPDX-License-Identifier: GPL-2.0-only #include <asm/trap_pf.h> #include <asm/segment.h> #include <asm/trapnr.h> #include "misc.h" static void set_idt_entry(int vector, void (*handler)(void)) { unsigned long address = (unsigned long)handler; gate_desc entry; memset(&entry, 0, sizeof(entry)); entry.offset_low = (u16)(address & 0xffff); entry.segment = __KERNEL_CS; entry.bits.type = GATE_TRAP; entry.bits.p = 1; entry.offset_middle = (u16)((address >> 16) & 0xffff); entry.offset_high = (u32)(address >> 32); memcpy(&boot_idt[vector], &entry, sizeof(entry)); } /* Have this here so we don't need to include <asm/desc.h> */ static void load_boot_idt(const struct desc_ptr *dtr) { asm volatile("lidt %0"::"m" (*dtr)); } /* Setup IDT before kernel jumping to .Lrelocated */ void load_stage1_idt(void) { boot_idt_desc.address = (unsigned long)boot_idt; if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) set_idt_entry(X86_TRAP_VC, boot_stage1_vc); load_boot_idt(&boot_idt_desc); } /* * Setup IDT after kernel jumping to .Lrelocated. * * initialize_identity_maps() needs a #PF handler to be setup * in order to be able to fault-in identity mapping ranges; see * do_boot_page_fault(). * * This #PF handler setup needs to happen in load_stage2_idt() where the * IDT is loaded and there the #VC IDT entry gets setup too. * * In order to be able to handle #VCs, one needs a GHCB which * gets setup with an already set up pagetable, which is done in * initialize_identity_maps(). And there's the catch 22: the boot #VC * handler do_boot_stage2_vc() needs to call early_setup_ghcb() itself * (and, especially set_page_decrypted()) because the SEV-ES setup code * cannot initialize a GHCB as there's no #PF handler yet... */ void load_stage2_idt(void) { boot_idt_desc.address = (unsigned long)boot_idt; set_idt_entry(X86_TRAP_PF, boot_page_fault); #ifdef CONFIG_AMD_MEM_ENCRYPT /* * Clear the second stage #VC handler in case guest types * needing #VC have not been detected. */ if (sev_status & BIT(1)) set_idt_entry(X86_TRAP_VC, boot_stage2_vc); else set_idt_entry(X86_TRAP_VC, NULL); #endif load_boot_idt(&boot_idt_desc); } void cleanup_exception_handling(void) { /* * Flush GHCB from cache and map it encrypted again when running as * SEV-ES guest. */ sev_es_shutdown_ghcb(); /* Set a null-idt, disabling #PF and #VC handling */ boot_idt_desc.size = 0; boot_idt_desc.address = 0; load_boot_idt(&boot_idt_desc); }