tools/testing/selftests/kvm/x86_64/evmcs_test.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2018, Red Hat, Inc.
 *
 * Tests for Enlightened VMCS, including nested guest state.
 */
#define _GNU_SOURCE /* for program_invocation_short_name */
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <linux/bitmap.h>

#include "test_util.h"

#include "kvm_util.h"

#include "vmx.h"

#define VCPU_ID		5
#define NMI_VECTOR	2

static int ud_count;

static void guest_ud_handler(struct ex_regs *regs)
{
	ud_count++;
	regs->rip += 3; /* VMLAUNCH */
}

static void guest_nmi_handler(struct ex_regs *regs)
{
}

/* Exits to L1 destroy GRPs! */
static inline void rdmsr_fs_base(void)
{
	__asm__ __volatile__ ("mov $0xc0000100, %%rcx; rdmsr" : : :
			      "rax", "rbx", "rcx", "rdx",
			      "rsi", "rdi", "r8", "r9", "r10", "r11", "r12",
			      "r13", "r14", "r15");
}
static inline void rdmsr_gs_base(void)
{
	__asm__ __volatile__ ("mov $0xc0000101, %%rcx; rdmsr" : : :
			      "rax", "rbx", "rcx", "rdx",
			      "rsi", "rdi", "r8", "r9", "r10", "r11", "r12",
			      "r13", "r14", "r15");
}

void l2_guest_code(void)
{
	GUEST_SYNC(7);

	GUEST_SYNC(8);

	/* Forced exit to L1 upon restore */
	GUEST_SYNC(9);

	vmcall();

	/* MSR-Bitmap tests */
	rdmsr_fs_base(); /* intercepted */
	rdmsr_fs_base(); /* intercepted */
	rdmsr_gs_base(); /* not intercepted */
	vmcall();
	rdmsr_gs_base(); /* intercepted */

	/* Done, exit to L1 and never come back.  */
	vmcall();
}

void guest_code(struct vmx_pages *vmx_pages)
{
#define L2_GUEST_STACK_SIZE 64
	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];

	x2apic_enable();

	GUEST_SYNC(1);
	GUEST_SYNC(2);

	enable_vp_assist(vmx_pages->vp_assist_gpa, vmx_pages->vp_assist);

	GUEST_ASSERT(vmx_pages->vmcs_gpa);
	GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
	GUEST_SYNC(3);
	GUEST_ASSERT(load_vmcs(vmx_pages));
	GUEST_ASSERT(vmptrstz() == vmx_pages->enlightened_vmcs_gpa);

	GUEST_SYNC(4);
	GUEST_ASSERT(vmptrstz() == vmx_pages->enlightened_vmcs_gpa);

	prepare_vmcs(vmx_pages, l2_guest_code,
		     &l2_guest_stack[L2_GUEST_STACK_SIZE]);

	GUEST_SYNC(5);
	GUEST_ASSERT(vmptrstz() == vmx_pages->enlightened_vmcs_gpa);
	current_evmcs->revision_id = -1u;
	GUEST_ASSERT(vmlaunch());
	current_evmcs->revision_id = EVMCS_VERSION;
	GUEST_SYNC(6);

	vmwrite(PIN_BASED_VM_EXEC_CONTROL, vmreadz(PIN_BASED_VM_EXEC_CONTROL) |
		PIN_BASED_NMI_EXITING);

	GUEST_ASSERT(!vmlaunch());
	GUEST_ASSERT(vmptrstz() == vmx_pages->enlightened_vmcs_gpa);

	/*
	 * NMI forces L2->L1 exit, resuming L2 and hope that EVMCS is
	 * up-to-date (RIP points where it should and not at the beginning
	 * of l2_guest_code(). GUEST_SYNC(9) checkes that.
	 */
	GUEST_ASSERT(!vmresume());

	GUEST_SYNC(10);

	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
	current_evmcs->guest_rip += 3; /* vmcall */

	/* Intercept RDMSR 0xc0000100 */
	vmwrite(CPU_BASED_VM_EXEC_CONTROL, vmreadz(CPU_BASED_VM_EXEC_CONTROL) |
		CPU_BASED_USE_MSR_BITMAPS);
	set_bit(MSR_FS_BASE & 0x1fff, vmx_pages->msr + 0x400);
	GUEST_ASSERT(!vmresume());
	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_MSR_READ);
	current_evmcs->guest_rip += 2; /* rdmsr */

	/* Enable enlightened MSR bitmap */
	current_evmcs->hv_enlightenments_control.msr_bitmap = 1;
	GUEST_ASSERT(!vmresume());
	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_MSR_READ);
	current_evmcs->guest_rip += 2; /* rdmsr */

	/* Intercept RDMSR 0xc0000101 without telling KVM about it */
	set_bit(MSR_GS_BASE & 0x1fff, vmx_pages->msr + 0x400);
	/* Make sure HV_VMX_ENLIGHTENED_CLEAN_FIELD_MSR_BITMAP is set */
	current_evmcs->hv_clean_fields |= HV_VMX_ENLIGHTENED_CLEAN_FIELD_MSR_BITMAP;
	GUEST_ASSERT(!vmresume());
	/* Make sure we don't see EXIT_REASON_MSR_READ here so eMSR bitmap works */
	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
	current_evmcs->guest_rip += 3; /* vmcall */

	/* Now tell KVM we've changed MSR-Bitmap */
	current_evmcs->hv_clean_fields &= ~HV_VMX_ENLIGHTENED_CLEAN_FIELD_MSR_BITMAP;
	GUEST_ASSERT(!vmresume());
	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_MSR_READ);
	current_evmcs->guest_rip += 2; /* rdmsr */

	GUEST_ASSERT(!vmresume());
	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
	GUEST_SYNC(11);

	/* Try enlightened vmptrld with an incorrect GPA */
	evmcs_vmptrld(0xdeadbeef, vmx_pages->enlightened_vmcs);
	GUEST_ASSERT(vmlaunch());
	GUEST_ASSERT(ud_count == 1);
	GUEST_DONE();
}

void inject_nmi(struct kvm_vm *vm)
{
	struct kvm_vcpu_events events;

	vcpu_events_get(vm, VCPU_ID, &events);

	events.nmi.pending = 1;
	events.flags |= KVM_VCPUEVENT_VALID_NMI_PENDING;

	vcpu_events_set(vm, VCPU_ID, &events);
}

static void save_restore_vm(struct kvm_vm *vm)
{
	struct kvm_regs regs1, regs2;
	struct kvm_x86_state *state;

	state = vcpu_save_state(vm, VCPU_ID);
	memset(&regs1, 0, sizeof(regs1));
	vcpu_regs_get(vm, VCPU_ID, &regs1);

	kvm_vm_release(vm);

	/* Restore state in a new VM.  */
	kvm_vm_restart(vm, O_RDWR);
	vm_vcpu_add(vm, VCPU_ID);
	vcpu_set_hv_cpuid(vm, VCPU_ID);
	vcpu_enable_evmcs(vm, VCPU_ID);
	vcpu_load_state(vm, VCPU_ID, state);
	kvm_x86_state_cleanup(state);

	memset(&regs2, 0, sizeof(regs2));
	vcpu_regs_get(vm, VCPU_ID, &regs2);
	TEST_ASSERT(!memcmp(&regs1, &regs2, sizeof(regs2)),
		    "Unexpected register values after vcpu_load_state; rdi: %lx rsi: %lx",
		    (ulong) regs2.rdi, (ulong) regs2.rsi);
}

int main(int argc, char *argv[])
{
	vm_vaddr_t vmx_pages_gva = 0;

	struct kvm_vm *vm;
	struct kvm_run *run;
	struct ucall uc;
	int stage;

	/* Create VM */
	vm = vm_create_default(VCPU_ID, 0, guest_code);

	if (!nested_vmx_supported() ||
	    !kvm_check_cap(KVM_CAP_NESTED_STATE) ||
	    !kvm_check_cap(KVM_CAP_HYPERV_ENLIGHTENED_VMCS)) {
		print_skip("Enlightened VMCS is unsupported");
		exit(KSFT_SKIP);
	}

	vcpu_set_hv_cpuid(vm, VCPU_ID);
	vcpu_enable_evmcs(vm, VCPU_ID);

	vcpu_alloc_vmx(vm, &vmx_pages_gva);
	vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva);

	vm_init_descriptor_tables(vm);
	vcpu_init_descriptor_tables(vm, VCPU_ID);
	vm_install_exception_handler(vm, UD_VECTOR, guest_ud_handler);
	vm_install_exception_handler(vm, NMI_VECTOR, guest_nmi_handler);

	pr_info("Running L1 which uses EVMCS to run L2\n");

	for (stage = 1;; stage++) {
		run = vcpu_state(vm, VCPU_ID);
		_vcpu_run(vm, VCPU_ID);
		TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
			    "Stage %d: unexpected exit reason: %u (%s),\n",
			    stage, run->exit_reason,
			    exit_reason_str(run->exit_reason));

		switch (get_ucall(vm, VCPU_ID, &uc)) {
		case UCALL_ABORT:
			TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0],
		      		  __FILE__, uc.args[1]);
			/* NOT REACHED */
		case UCALL_SYNC:
			break;
		case UCALL_DONE:
			goto done;
		default:
			TEST_FAIL("Unknown ucall %lu", uc.cmd);
		}

		/* UCALL_SYNC is handled here.  */
		TEST_ASSERT(!strcmp((const char *)uc.args[0], "hello") &&
			    uc.args[1] == stage, "Stage %d: Unexpected register values vmexit, got %lx",
			    stage, (ulong)uc.args[1]);

		save_restore_vm(vm);

		/* Force immediate L2->L1 exit before resuming */
		if (stage == 8) {
			pr_info("Injecting NMI into L1 before L2 had a chance to run after restore\n");
			inject_nmi(vm);
		}

		/*
		 * Do KVM_GET_NESTED_STATE/KVM_SET_NESTED_STATE for a freshly
		 * restored VM (before the first KVM_RUN) to check that
		 * KVM_STATE_NESTED_EVMCS is not lost.
		 */
		if (stage == 9) {
			pr_info("Trying extra KVM_GET_NESTED_STATE/KVM_SET_NESTED_STATE cycle\n");
			save_restore_vm(vm);
		}
	}

done:
	kvm_vm_free(vm);
}