kvm: selftests: add vmx_tsc_adjust_test

The test checks the behavior of setting MSR_IA32_TSC in a nested guest,
and the TSC_OFFSET VMCS field in general.  It also introduces the testing
infrastructure for Intel nested virtualization.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 231 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/vmx_tsc_adjust_test.c b/tools/testing/selftests/kvm/vmx_tsc_adjust_test.c
new file mode 100644
index 000000000000..8f7f62093add
--- /dev/null
+++ b/tools/testing/selftests/kvm/vmx_tsc_adjust_test.c
@@ -0,0 +1,231 @@
+/*
+ * gtests/tests/vmx_tsc_adjust_test.c
+ *
+ * Copyright (C) 2018, Google LLC.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ *
+ *
+ * IA32_TSC_ADJUST test
+ *
+ * According to the SDM, "if an execution of WRMSR to the
+ * IA32_TIME_STAMP_COUNTER MSR adds (or subtracts) value X from the TSC,
+ * the logical processor also adds (or subtracts) value X from the
+ * IA32_TSC_ADJUST MSR.
+ *
+ * Note that when L1 doesn't intercept writes to IA32_TSC, a
+ * WRMSR(IA32_TSC) from L2 sets L1's TSC value, not L2's perceived TSC
+ * value.
+ *
+ * This test verifies that this unusual case is handled correctly.
+ */
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "x86.h"
+#include "vmx.h"
+
+#include <string.h>
+#include <sys/ioctl.h>
+
+#ifndef MSR_IA32_TSC_ADJUST
+#define MSR_IA32_TSC_ADJUST 0x3b
+#endif
+
+#define PAGE_SIZE	4096
+#define VCPU_ID		5
+
+#define TSC_ADJUST_VALUE (1ll << 32)
+#define TSC_OFFSET_VALUE -(1ll << 48)
+
+enum {
+	PORT_ABORT = 0x1000,
+	PORT_REPORT,
+	PORT_DONE,
+};
+
+struct vmx_page {
+	vm_vaddr_t virt;
+	vm_paddr_t phys;
+};
+
+enum {
+	VMXON_PAGE = 0,
+	VMCS_PAGE,
+	MSR_BITMAP_PAGE,
+
+	NUM_VMX_PAGES,
+};
+
+struct kvm_single_msr {
+	struct kvm_msrs header;
+	struct kvm_msr_entry entry;
+} __attribute__((packed));
+
+/* The virtual machine object. */
+static struct kvm_vm *vm;
+
+/* Array of vmx_page descriptors that is shared with the guest. */
+struct vmx_page *vmx_pages;
+
+#define exit_to_l0(_port, _arg) do_exit_to_l0(_port, (unsigned long) (_arg))
+static void do_exit_to_l0(uint16_t port, unsigned long arg)
+{
+	__asm__ __volatile__("in %[port], %%al"
+		:
+		: [port]"d"(port), "D"(arg)
+		: "rax");
+}
+
+
+#define GUEST_ASSERT(_condition) do {					     \
+	if (!(_condition))						     \
+		exit_to_l0(PORT_ABORT, "Failed guest assert: " #_condition); \
+} while (0)
+
+static void check_ia32_tsc_adjust(int64_t max)
+{
+	int64_t adjust;
+
+	adjust = rdmsr(MSR_IA32_TSC_ADJUST);
+	exit_to_l0(PORT_REPORT, adjust);
+	GUEST_ASSERT(adjust <= max);
+}
+
+static void l2_guest_code(void)
+{
+	uint64_t l1_tsc = rdtsc() - TSC_OFFSET_VALUE;
+
+	wrmsr(MSR_IA32_TSC, l1_tsc - TSC_ADJUST_VALUE);
+	check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
+
+	/* Exit to L1 */
+	__asm__ __volatile__("vmcall");
+}
+
+static void l1_guest_code(struct vmx_page *vmx_pages)
+{
+#define L2_GUEST_STACK_SIZE 64
+	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+	uint32_t control;
+	uintptr_t save_cr3;
+
+	GUEST_ASSERT(rdtsc() < TSC_ADJUST_VALUE);
+	wrmsr(MSR_IA32_TSC, rdtsc() - TSC_ADJUST_VALUE);
+	check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
+
+	prepare_for_vmx_operation();
+
+	/* Enter VMX root operation. */
+	*(uint32_t *)vmx_pages[VMXON_PAGE].virt = vmcs_revision();
+	GUEST_ASSERT(!vmxon(vmx_pages[VMXON_PAGE].phys));
+
+	/* Load a VMCS. */
+	*(uint32_t *)vmx_pages[VMCS_PAGE].virt = vmcs_revision();
+	GUEST_ASSERT(!vmclear(vmx_pages[VMCS_PAGE].phys));
+	GUEST_ASSERT(!vmptrld(vmx_pages[VMCS_PAGE].phys));
+
+	/* Prepare the VMCS for L2 execution. */
+	prepare_vmcs(l2_guest_code, &l2_guest_stack[L2_GUEST_STACK_SIZE]);
+	control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
+	control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETING;
+	vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
+	vmwrite(MSR_BITMAP, vmx_pages[MSR_BITMAP_PAGE].phys);
+	vmwrite(TSC_OFFSET, TSC_OFFSET_VALUE);
+
+	/* Jump into L2.  First, test failure to load guest CR3.  */
+	save_cr3 = vmreadz(GUEST_CR3);
+	vmwrite(GUEST_CR3, -1ull);
+	GUEST_ASSERT(!vmlaunch());
+	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) ==
+		     (EXIT_REASON_FAILED_VMENTRY | EXIT_REASON_INVALID_STATE));
+	check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
+	vmwrite(GUEST_CR3, save_cr3);
+
+	GUEST_ASSERT(!vmlaunch());
+	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
+
+	check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
+
+	exit_to_l0(PORT_DONE, 0);
+}
+
+static void allocate_vmx_page(struct vmx_page *page)
+{
+	vm_vaddr_t virt;
+
+	virt = vm_vaddr_alloc(vm, PAGE_SIZE, 0, 0, 0);
+	memset(addr_gva2hva(vm, virt), 0, PAGE_SIZE);
+
+	page->virt = virt;
+	page->phys = addr_gva2gpa(vm, virt);
+}
+
+static vm_vaddr_t allocate_vmx_pages(void)
+{
+	vm_vaddr_t vmx_pages_vaddr;
+	int i;
+
+	vmx_pages_vaddr = vm_vaddr_alloc(
+		vm, sizeof(struct vmx_page) * NUM_VMX_PAGES, 0, 0, 0);
+
+	vmx_pages = (void *) addr_gva2hva(vm, vmx_pages_vaddr);
+
+	for (i = 0; i < NUM_VMX_PAGES; i++)
+		allocate_vmx_page(&vmx_pages[i]);
+
+	return vmx_pages_vaddr;
+}
+
+void report(int64_t val)
+{
+	printf("IA32_TSC_ADJUST is %ld (%lld * TSC_ADJUST_VALUE + %lld).\n",
+	       val, val / TSC_ADJUST_VALUE, val % TSC_ADJUST_VALUE);
+}
+
+int main(int argc, char *argv[])
+{
+	vm_vaddr_t vmx_pages_vaddr;
+	struct kvm_cpuid_entry2 *entry = kvm_get_supported_cpuid_entry(1);
+
+	if (!(entry->ecx & CPUID_VMX)) {
+		printf("nested VMX not enabled, skipping test");
+		return 0;
+	}
+
+	vm = vm_create_default_vmx(VCPU_ID, (void *) l1_guest_code);
+
+	/* Allocate VMX pages and shared descriptors (vmx_pages). */
+	vmx_pages_vaddr = allocate_vmx_pages();
+	vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_vaddr);
+
+	for (;;) {
+		volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID);
+		struct kvm_regs regs;
+
+		vcpu_run(vm, VCPU_ID);
+		TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+			    "Got exit_reason other than KVM_EXIT_IO: %u (%s),\n",
+			    run->exit_reason,
+			    exit_reason_str(run->exit_reason));
+
+		vcpu_regs_get(vm, VCPU_ID, &regs);
+
+		switch (run->io.port) {
+		case PORT_ABORT:
+			TEST_ASSERT(false, "%s", (const char *) regs.rdi);
+			/* NOT REACHED */
+		case PORT_REPORT:
+			report(regs.rdi);
+			break;
+		case PORT_DONE:
+			goto done;
+		default:
+			TEST_ASSERT(false, "Unknown port 0x%x.", run->io.port);
+		}
+	}
+
+	kvm_vm_free(vm);
+done:
+	return 0;
+}