Contributors: 8
Author Tokens Token Proportion Commits Commit Proportion
Aaron Lewis 2363 77.48% 3 23.08%
Alexander Graf 488 16.00% 1 7.69%
Sean Christopherson 109 3.57% 4 30.77%
Thomas Huth 65 2.13% 1 7.69%
Vipin Sharma 12 0.39% 1 7.69%
Paolo Bonzini 8 0.26% 1 7.69%
Colton Lewis 3 0.10% 1 7.69%
Ricardo Koller 2 0.07% 1 7.69%
Total 3050 13 


// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2020, Google LLC.
 *
 * Tests for exiting into userspace on registered MSRs
 */
#include <sys/ioctl.h>

#include "kvm_test_harness.h"
#include "test_util.h"
#include "kvm_util.h"
#include "vmx.h"

#define MSR_NON_EXISTENT 0x474f4f00

static u64 deny_bits = 0;
struct kvm_msr_filter filter_allow = {
	.flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
	.ranges = {
		{
			.flags = KVM_MSR_FILTER_READ |
				 KVM_MSR_FILTER_WRITE,
			.nmsrs = 1,
			/* Test an MSR the kernel knows about. */
			.base = MSR_IA32_XSS,
			.bitmap = (uint8_t*)&deny_bits,
		}, {
			.flags = KVM_MSR_FILTER_READ |
				 KVM_MSR_FILTER_WRITE,
			.nmsrs = 1,
			/* Test an MSR the kernel doesn't know about. */
			.base = MSR_IA32_FLUSH_CMD,
			.bitmap = (uint8_t*)&deny_bits,
		}, {
			.flags = KVM_MSR_FILTER_READ |
				 KVM_MSR_FILTER_WRITE,
			.nmsrs = 1,
			/* Test a fabricated MSR that no one knows about. */
			.base = MSR_NON_EXISTENT,
			.bitmap = (uint8_t*)&deny_bits,
		},
	},
};

struct kvm_msr_filter filter_fs = {
	.flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
	.ranges = {
		{
			.flags = KVM_MSR_FILTER_READ,
			.nmsrs = 1,
			.base = MSR_FS_BASE,
			.bitmap = (uint8_t*)&deny_bits,
		},
	},
};

struct kvm_msr_filter filter_gs = {
	.flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
	.ranges = {
		{
			.flags = KVM_MSR_FILTER_READ,
			.nmsrs = 1,
			.base = MSR_GS_BASE,
			.bitmap = (uint8_t*)&deny_bits,
		},
	},
};

static uint64_t msr_non_existent_data;
static int guest_exception_count;
static u32 msr_reads, msr_writes;

static u8 bitmap_00000000[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
static u8 bitmap_00000000_write[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
static u8 bitmap_40000000[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
static u8 bitmap_c0000000[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
static u8 bitmap_c0000000_read[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
static u8 bitmap_deadbeef[1] = { 0x1 };

static void deny_msr(uint8_t *bitmap, u32 msr)
{
	u32 idx = msr & (KVM_MSR_FILTER_MAX_BITMAP_SIZE - 1);

	bitmap[idx / 8] &= ~(1 << (idx % 8));
}

static void prepare_bitmaps(void)
{
	memset(bitmap_00000000, 0xff, sizeof(bitmap_00000000));
	memset(bitmap_00000000_write, 0xff, sizeof(bitmap_00000000_write));
	memset(bitmap_40000000, 0xff, sizeof(bitmap_40000000));
	memset(bitmap_c0000000, 0xff, sizeof(bitmap_c0000000));
	memset(bitmap_c0000000_read, 0xff, sizeof(bitmap_c0000000_read));

	deny_msr(bitmap_00000000_write, MSR_IA32_POWER_CTL);
	deny_msr(bitmap_c0000000_read, MSR_SYSCALL_MASK);
	deny_msr(bitmap_c0000000_read, MSR_GS_BASE);
}

struct kvm_msr_filter filter_deny = {
	.flags = KVM_MSR_FILTER_DEFAULT_DENY,
	.ranges = {
		{
			.flags = KVM_MSR_FILTER_READ,
			.base = 0x00000000,
			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
			.bitmap = bitmap_00000000,
		}, {
			.flags = KVM_MSR_FILTER_WRITE,
			.base = 0x00000000,
			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
			.bitmap = bitmap_00000000_write,
		}, {
			.flags = KVM_MSR_FILTER_READ | KVM_MSR_FILTER_WRITE,
			.base = 0x40000000,
			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
			.bitmap = bitmap_40000000,
		}, {
			.flags = KVM_MSR_FILTER_READ,
			.base = 0xc0000000,
			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
			.bitmap = bitmap_c0000000_read,
		}, {
			.flags = KVM_MSR_FILTER_WRITE,
			.base = 0xc0000000,
			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
			.bitmap = bitmap_c0000000,
		}, {
			.flags = KVM_MSR_FILTER_WRITE | KVM_MSR_FILTER_READ,
			.base = 0xdeadbeef,
			.nmsrs = 1,
			.bitmap = bitmap_deadbeef,
		},
	},
};

struct kvm_msr_filter no_filter_deny = {
	.flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
};

/*
 * Note: Force test_rdmsr() to not be inlined to prevent the labels,
 * rdmsr_start and rdmsr_end, from being defined multiple times.
 */
static noinline uint64_t test_rdmsr(uint32_t msr)
{
	uint32_t a, d;

	guest_exception_count = 0;

	__asm__ __volatile__("rdmsr_start: rdmsr; rdmsr_end:" :
			"=a"(a), "=d"(d) : "c"(msr) : "memory");

	return a | ((uint64_t) d << 32);
}

/*
 * Note: Force test_wrmsr() to not be inlined to prevent the labels,
 * wrmsr_start and wrmsr_end, from being defined multiple times.
 */
static noinline void test_wrmsr(uint32_t msr, uint64_t value)
{
	uint32_t a = value;
	uint32_t d = value >> 32;

	guest_exception_count = 0;

	__asm__ __volatile__("wrmsr_start: wrmsr; wrmsr_end:" ::
			"a"(a), "d"(d), "c"(msr) : "memory");
}

extern char rdmsr_start, rdmsr_end;
extern char wrmsr_start, wrmsr_end;

/*
 * Note: Force test_em_rdmsr() to not be inlined to prevent the labels,
 * rdmsr_start and rdmsr_end, from being defined multiple times.
 */
static noinline uint64_t test_em_rdmsr(uint32_t msr)
{
	uint32_t a, d;

	guest_exception_count = 0;

	__asm__ __volatile__(KVM_FEP "em_rdmsr_start: rdmsr; em_rdmsr_end:" :
			"=a"(a), "=d"(d) : "c"(msr) : "memory");

	return a | ((uint64_t) d << 32);
}

/*
 * Note: Force test_em_wrmsr() to not be inlined to prevent the labels,
 * wrmsr_start and wrmsr_end, from being defined multiple times.
 */
static noinline void test_em_wrmsr(uint32_t msr, uint64_t value)
{
	uint32_t a = value;
	uint32_t d = value >> 32;

	guest_exception_count = 0;

	__asm__ __volatile__(KVM_FEP "em_wrmsr_start: wrmsr; em_wrmsr_end:" ::
			"a"(a), "d"(d), "c"(msr) : "memory");
}

extern char em_rdmsr_start, em_rdmsr_end;
extern char em_wrmsr_start, em_wrmsr_end;

static void guest_code_filter_allow(void)
{
	uint64_t data;

	/*
	 * Test userspace intercepting rdmsr / wrmsr for MSR_IA32_XSS.
	 *
	 * A GP is thrown if anything other than 0 is written to
	 * MSR_IA32_XSS.
	 */
	data = test_rdmsr(MSR_IA32_XSS);
	GUEST_ASSERT(data == 0);
	GUEST_ASSERT(guest_exception_count == 0);

	test_wrmsr(MSR_IA32_XSS, 0);
	GUEST_ASSERT(guest_exception_count == 0);

	test_wrmsr(MSR_IA32_XSS, 1);
	GUEST_ASSERT(guest_exception_count == 1);

	/*
	 * Test userspace intercepting rdmsr / wrmsr for MSR_IA32_FLUSH_CMD.
	 *
	 * A GP is thrown if MSR_IA32_FLUSH_CMD is read
	 * from or if a value other than 1 is written to it.
	 */
	test_rdmsr(MSR_IA32_FLUSH_CMD);
	GUEST_ASSERT(guest_exception_count == 1);

	test_wrmsr(MSR_IA32_FLUSH_CMD, 0);
	GUEST_ASSERT(guest_exception_count == 1);

	test_wrmsr(MSR_IA32_FLUSH_CMD, 1);
	GUEST_ASSERT(guest_exception_count == 0);

	/*
	 * Test userspace intercepting rdmsr / wrmsr for MSR_NON_EXISTENT.
	 *
	 * Test that a fabricated MSR can pass through the kernel
	 * and be handled in userspace.
	 */
	test_wrmsr(MSR_NON_EXISTENT, 2);
	GUEST_ASSERT(guest_exception_count == 0);

	data = test_rdmsr(MSR_NON_EXISTENT);
	GUEST_ASSERT(data == 2);
	GUEST_ASSERT(guest_exception_count == 0);

	if (is_forced_emulation_enabled) {
		/* Let userspace know we aren't done. */
		GUEST_SYNC(0);

		/*
		 * Now run the same tests with the instruction emulator.
		 */
		data = test_em_rdmsr(MSR_IA32_XSS);
		GUEST_ASSERT(data == 0);
		GUEST_ASSERT(guest_exception_count == 0);
		test_em_wrmsr(MSR_IA32_XSS, 0);
		GUEST_ASSERT(guest_exception_count == 0);
		test_em_wrmsr(MSR_IA32_XSS, 1);
		GUEST_ASSERT(guest_exception_count == 1);

		test_em_rdmsr(MSR_IA32_FLUSH_CMD);
		GUEST_ASSERT(guest_exception_count == 1);
		test_em_wrmsr(MSR_IA32_FLUSH_CMD, 0);
		GUEST_ASSERT(guest_exception_count == 1);
		test_em_wrmsr(MSR_IA32_FLUSH_CMD, 1);
		GUEST_ASSERT(guest_exception_count == 0);

		test_em_wrmsr(MSR_NON_EXISTENT, 2);
		GUEST_ASSERT(guest_exception_count == 0);
		data = test_em_rdmsr(MSR_NON_EXISTENT);
		GUEST_ASSERT(data == 2);
		GUEST_ASSERT(guest_exception_count == 0);
	}

	GUEST_DONE();
}

static void guest_msr_calls(bool trapped)
{
	/* This goes into the in-kernel emulation */
	wrmsr(MSR_SYSCALL_MASK, 0);

	if (trapped) {
		/* This goes into user space emulation */
		GUEST_ASSERT(rdmsr(MSR_SYSCALL_MASK) == MSR_SYSCALL_MASK);
		GUEST_ASSERT(rdmsr(MSR_GS_BASE) == MSR_GS_BASE);
	} else {
		GUEST_ASSERT(rdmsr(MSR_SYSCALL_MASK) != MSR_SYSCALL_MASK);
		GUEST_ASSERT(rdmsr(MSR_GS_BASE) != MSR_GS_BASE);
	}

	/* If trapped == true, this goes into user space emulation */
	wrmsr(MSR_IA32_POWER_CTL, 0x1234);

	/* This goes into the in-kernel emulation */
	rdmsr(MSR_IA32_POWER_CTL);

	/* Invalid MSR, should always be handled by user space exit */
	GUEST_ASSERT(rdmsr(0xdeadbeef) == 0xdeadbeef);
	wrmsr(0xdeadbeef, 0x1234);
}

static void guest_code_filter_deny(void)
{
	guest_msr_calls(true);

	/*
	 * Disable msr filtering, so that the kernel
	 * handles everything in the next round
	 */
	GUEST_SYNC(0);

	guest_msr_calls(false);

	GUEST_DONE();
}

static void guest_code_permission_bitmap(void)
{
	uint64_t data;

	data = test_rdmsr(MSR_FS_BASE);
	GUEST_ASSERT(data == MSR_FS_BASE);
	data = test_rdmsr(MSR_GS_BASE);
	GUEST_ASSERT(data != MSR_GS_BASE);

	/* Let userspace know to switch the filter */
	GUEST_SYNC(0);

	data = test_rdmsr(MSR_FS_BASE);
	GUEST_ASSERT(data != MSR_FS_BASE);
	data = test_rdmsr(MSR_GS_BASE);
	GUEST_ASSERT(data == MSR_GS_BASE);

	GUEST_DONE();
}

static void __guest_gp_handler(struct ex_regs *regs,
			       char *r_start, char *r_end,
			       char *w_start, char *w_end)
{
	if (regs->rip == (uintptr_t)r_start) {
		regs->rip = (uintptr_t)r_end;
		regs->rax = 0;
		regs->rdx = 0;
	} else if (regs->rip == (uintptr_t)w_start) {
		regs->rip = (uintptr_t)w_end;
	} else {
		GUEST_ASSERT(!"RIP is at an unknown location!");
	}

	++guest_exception_count;
}

static void guest_gp_handler(struct ex_regs *regs)
{
	__guest_gp_handler(regs, &rdmsr_start, &rdmsr_end,
			   &wrmsr_start, &wrmsr_end);
}

static void guest_fep_gp_handler(struct ex_regs *regs)
{
	__guest_gp_handler(regs, &em_rdmsr_start, &em_rdmsr_end,
			   &em_wrmsr_start, &em_wrmsr_end);
}

static void check_for_guest_assert(struct kvm_vcpu *vcpu)
{
	struct ucall uc;

	if (vcpu->run->exit_reason == KVM_EXIT_IO &&
	    get_ucall(vcpu, &uc) == UCALL_ABORT) {
		REPORT_GUEST_ASSERT(uc);
	}
}

static void process_rdmsr(struct kvm_vcpu *vcpu, uint32_t msr_index)
{
	struct kvm_run *run = vcpu->run;

	check_for_guest_assert(vcpu);

	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_X86_RDMSR);
	TEST_ASSERT(run->msr.index == msr_index,
			"Unexpected msr (0x%04x), expected 0x%04x",
			run->msr.index, msr_index);

	switch (run->msr.index) {
	case MSR_IA32_XSS:
		run->msr.data = 0;
		break;
	case MSR_IA32_FLUSH_CMD:
		run->msr.error = 1;
		break;
	case MSR_NON_EXISTENT:
		run->msr.data = msr_non_existent_data;
		break;
	case MSR_FS_BASE:
		run->msr.data = MSR_FS_BASE;
		break;
	case MSR_GS_BASE:
		run->msr.data = MSR_GS_BASE;
		break;
	default:
		TEST_ASSERT(false, "Unexpected MSR: 0x%04x", run->msr.index);
	}
}

static void process_wrmsr(struct kvm_vcpu *vcpu, uint32_t msr_index)
{
	struct kvm_run *run = vcpu->run;

	check_for_guest_assert(vcpu);

	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_X86_WRMSR);
	TEST_ASSERT(run->msr.index == msr_index,
			"Unexpected msr (0x%04x), expected 0x%04x",
			run->msr.index, msr_index);

	switch (run->msr.index) {
	case MSR_IA32_XSS:
		if (run->msr.data != 0)
			run->msr.error = 1;
		break;
	case MSR_IA32_FLUSH_CMD:
		if (run->msr.data != 1)
			run->msr.error = 1;
		break;
	case MSR_NON_EXISTENT:
		msr_non_existent_data = run->msr.data;
		break;
	default:
		TEST_ASSERT(false, "Unexpected MSR: 0x%04x", run->msr.index);
	}
}

static void process_ucall_done(struct kvm_vcpu *vcpu)
{
	struct ucall uc;

	check_for_guest_assert(vcpu);

	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);

	TEST_ASSERT(get_ucall(vcpu, &uc) == UCALL_DONE,
		    "Unexpected ucall command: %lu, expected UCALL_DONE (%d)",
		    uc.cmd, UCALL_DONE);
}

static uint64_t process_ucall(struct kvm_vcpu *vcpu)
{
	struct ucall uc = {};

	check_for_guest_assert(vcpu);

	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);

	switch (get_ucall(vcpu, &uc)) {
	case UCALL_SYNC:
		break;
	case UCALL_ABORT:
		check_for_guest_assert(vcpu);
		break;
	case UCALL_DONE:
		process_ucall_done(vcpu);
		break;
	default:
		TEST_ASSERT(false, "Unexpected ucall");
	}

	return uc.cmd;
}

static void run_guest_then_process_rdmsr(struct kvm_vcpu *vcpu,
					 uint32_t msr_index)
{
	vcpu_run(vcpu);
	process_rdmsr(vcpu, msr_index);
}

static void run_guest_then_process_wrmsr(struct kvm_vcpu *vcpu,
					 uint32_t msr_index)
{
	vcpu_run(vcpu);
	process_wrmsr(vcpu, msr_index);
}

static uint64_t run_guest_then_process_ucall(struct kvm_vcpu *vcpu)
{
	vcpu_run(vcpu);
	return process_ucall(vcpu);
}

static void run_guest_then_process_ucall_done(struct kvm_vcpu *vcpu)
{
	vcpu_run(vcpu);
	process_ucall_done(vcpu);
}

KVM_ONE_VCPU_TEST_SUITE(user_msr);

KVM_ONE_VCPU_TEST(user_msr, msr_filter_allow, guest_code_filter_allow)
{
	struct kvm_vm *vm = vcpu->vm;
	uint64_t cmd;
	int rc;

	rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
	TEST_ASSERT(rc, "KVM_CAP_X86_USER_SPACE_MSR is available");
	vm_enable_cap(vm, KVM_CAP_X86_USER_SPACE_MSR, KVM_MSR_EXIT_REASON_FILTER);

	rc = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
	TEST_ASSERT(rc, "KVM_CAP_X86_MSR_FILTER is available");

	vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_allow);

	vm_install_exception_handler(vm, GP_VECTOR, guest_gp_handler);

	/* Process guest code userspace exits. */
	run_guest_then_process_rdmsr(vcpu, MSR_IA32_XSS);
	run_guest_then_process_wrmsr(vcpu, MSR_IA32_XSS);
	run_guest_then_process_wrmsr(vcpu, MSR_IA32_XSS);

	run_guest_then_process_rdmsr(vcpu, MSR_IA32_FLUSH_CMD);
	run_guest_then_process_wrmsr(vcpu, MSR_IA32_FLUSH_CMD);
	run_guest_then_process_wrmsr(vcpu, MSR_IA32_FLUSH_CMD);

	run_guest_then_process_wrmsr(vcpu, MSR_NON_EXISTENT);
	run_guest_then_process_rdmsr(vcpu, MSR_NON_EXISTENT);

	vcpu_run(vcpu);
	cmd = process_ucall(vcpu);

	if (is_forced_emulation_enabled) {
		TEST_ASSERT_EQ(cmd, UCALL_SYNC);
		vm_install_exception_handler(vm, GP_VECTOR, guest_fep_gp_handler);

		/* Process emulated rdmsr and wrmsr instructions. */
		run_guest_then_process_rdmsr(vcpu, MSR_IA32_XSS);
		run_guest_then_process_wrmsr(vcpu, MSR_IA32_XSS);
		run_guest_then_process_wrmsr(vcpu, MSR_IA32_XSS);

		run_guest_then_process_rdmsr(vcpu, MSR_IA32_FLUSH_CMD);
		run_guest_then_process_wrmsr(vcpu, MSR_IA32_FLUSH_CMD);
		run_guest_then_process_wrmsr(vcpu, MSR_IA32_FLUSH_CMD);

		run_guest_then_process_wrmsr(vcpu, MSR_NON_EXISTENT);
		run_guest_then_process_rdmsr(vcpu, MSR_NON_EXISTENT);

		/* Confirm the guest completed without issues. */
		run_guest_then_process_ucall_done(vcpu);
	} else {
		TEST_ASSERT_EQ(cmd, UCALL_DONE);
		printf("To run the instruction emulated tests set the module parameter 'kvm.force_emulation_prefix=1'\n");
	}
}

static int handle_ucall(struct kvm_vcpu *vcpu)
{
	struct ucall uc;

	switch (get_ucall(vcpu, &uc)) {
	case UCALL_ABORT:
		REPORT_GUEST_ASSERT(uc);
		break;
	case UCALL_SYNC:
		vm_ioctl(vcpu->vm, KVM_X86_SET_MSR_FILTER, &no_filter_deny);
		break;
	case UCALL_DONE:
		return 1;
	default:
		TEST_FAIL("Unknown ucall %lu", uc.cmd);
	}

	return 0;
}

static void handle_rdmsr(struct kvm_run *run)
{
	run->msr.data = run->msr.index;
	msr_reads++;

	if (run->msr.index == MSR_SYSCALL_MASK ||
	    run->msr.index == MSR_GS_BASE) {
		TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_FILTER,
			    "MSR read trap w/o access fault");
	}

	if (run->msr.index == 0xdeadbeef) {
		TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_UNKNOWN,
			    "MSR deadbeef read trap w/o inval fault");
	}
}

static void handle_wrmsr(struct kvm_run *run)
{
	/* ignore */
	msr_writes++;

	if (run->msr.index == MSR_IA32_POWER_CTL) {
		TEST_ASSERT(run->msr.data == 0x1234,
			    "MSR data for MSR_IA32_POWER_CTL incorrect");
		TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_FILTER,
			    "MSR_IA32_POWER_CTL trap w/o access fault");
	}

	if (run->msr.index == 0xdeadbeef) {
		TEST_ASSERT(run->msr.data == 0x1234,
			    "MSR data for deadbeef incorrect");
		TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_UNKNOWN,
			    "deadbeef trap w/o inval fault");
	}
}

KVM_ONE_VCPU_TEST(user_msr, msr_filter_deny, guest_code_filter_deny)
{
	struct kvm_vm *vm = vcpu->vm;
	struct kvm_run *run = vcpu->run;
	int rc;

	rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
	TEST_ASSERT(rc, "KVM_CAP_X86_USER_SPACE_MSR is available");
	vm_enable_cap(vm, KVM_CAP_X86_USER_SPACE_MSR, KVM_MSR_EXIT_REASON_INVAL |
						      KVM_MSR_EXIT_REASON_UNKNOWN |
						      KVM_MSR_EXIT_REASON_FILTER);

	rc = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
	TEST_ASSERT(rc, "KVM_CAP_X86_MSR_FILTER is available");

	prepare_bitmaps();
	vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_deny);

	while (1) {
		vcpu_run(vcpu);

		switch (run->exit_reason) {
		case KVM_EXIT_X86_RDMSR:
			handle_rdmsr(run);
			break;
		case KVM_EXIT_X86_WRMSR:
			handle_wrmsr(run);
			break;
		case KVM_EXIT_IO:
			if (handle_ucall(vcpu))
				goto done;
			break;
		}

	}

done:
	TEST_ASSERT(msr_reads == 4, "Handled 4 rdmsr in user space");
	TEST_ASSERT(msr_writes == 3, "Handled 3 wrmsr in user space");
}

KVM_ONE_VCPU_TEST(user_msr, msr_permission_bitmap, guest_code_permission_bitmap)
{
	struct kvm_vm *vm = vcpu->vm;
	int rc;

	rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
	TEST_ASSERT(rc, "KVM_CAP_X86_USER_SPACE_MSR is available");
	vm_enable_cap(vm, KVM_CAP_X86_USER_SPACE_MSR, KVM_MSR_EXIT_REASON_FILTER);

	rc = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
	TEST_ASSERT(rc, "KVM_CAP_X86_MSR_FILTER is available");

	vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_fs);
	run_guest_then_process_rdmsr(vcpu, MSR_FS_BASE);
	TEST_ASSERT(run_guest_then_process_ucall(vcpu) == UCALL_SYNC,
		    "Expected ucall state to be UCALL_SYNC.");
	vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_gs);
	run_guest_then_process_rdmsr(vcpu, MSR_GS_BASE);
	run_guest_then_process_ucall_done(vcpu);
}

#define test_user_exit_msr_ioctl(vm, cmd, arg, flag, valid_mask)	\
({									\
	int r = __vm_ioctl(vm, cmd, arg);				\
									\
	if (flag & valid_mask)						\
		TEST_ASSERT(!r, __KVM_IOCTL_ERROR(#cmd, r));		\
	else								\
		TEST_ASSERT(r == -1 && errno == EINVAL,			\
			    "Wanted EINVAL for %s with flag = 0x%llx, got  rc: %i errno: %i (%s)", \
			    #cmd, flag, r, errno,  strerror(errno));	\
})

static void run_user_space_msr_flag_test(struct kvm_vm *vm)
{
	struct kvm_enable_cap cap = { .cap = KVM_CAP_X86_USER_SPACE_MSR };
	int nflags = sizeof(cap.args[0]) * BITS_PER_BYTE;
	int rc;
	int i;

	rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
	TEST_ASSERT(rc, "KVM_CAP_X86_USER_SPACE_MSR is available");

	for (i = 0; i < nflags; i++) {
		cap.args[0] = BIT_ULL(i);
		test_user_exit_msr_ioctl(vm, KVM_ENABLE_CAP, &cap,
			   BIT_ULL(i), KVM_MSR_EXIT_REASON_VALID_MASK);
	}
}

static void run_msr_filter_flag_test(struct kvm_vm *vm)
{
	u64 deny_bits = 0;
	struct kvm_msr_filter filter = {
		.flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
		.ranges = {
			{
				.flags = KVM_MSR_FILTER_READ,
				.nmsrs = 1,
				.base = 0,
				.bitmap = (uint8_t *)&deny_bits,
			},
		},
	};
	int nflags;
	int rc;
	int i;

	rc = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
	TEST_ASSERT(rc, "KVM_CAP_X86_MSR_FILTER is available");

	nflags = sizeof(filter.flags) * BITS_PER_BYTE;
	for (i = 0; i < nflags; i++) {
		filter.flags = BIT_ULL(i);
		test_user_exit_msr_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter,
			   BIT_ULL(i), KVM_MSR_FILTER_VALID_MASK);
	}

	filter.flags = KVM_MSR_FILTER_DEFAULT_ALLOW;
	nflags = sizeof(filter.ranges[0].flags) * BITS_PER_BYTE;
	for (i = 0; i < nflags; i++) {
		filter.ranges[0].flags = BIT_ULL(i);
		test_user_exit_msr_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter,
			   BIT_ULL(i), KVM_MSR_FILTER_RANGE_VALID_MASK);
	}
}

/* Test that attempts to write to the unused bits in a flag fails. */
KVM_ONE_VCPU_TEST(user_msr, user_exit_msr_flags, NULL)
{
	struct kvm_vm *vm = vcpu->vm;

	/* Test flags for KVM_CAP_X86_USER_SPACE_MSR. */
	run_user_space_msr_flag_test(vm);

	/* Test flags and range flags for KVM_X86_SET_MSR_FILTER. */
	run_msr_filter_flag_test(vm);
}

int main(int argc, char *argv[])
{
	return test_harness_run(argc, argv);
}