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/*
* 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>
#include "../kselftest.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)) {
fprintf(stderr, "nested VMX not enabled, skipping test\n");
exit(KSFT_SKIP);
}
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, ®s);
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;
}
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