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// SPDX-License-Identifier: GPL-2.0-only
/*
* vmx_tsc_adjust_test
*
* Copyright (C) 2018, Google LLC.
*
* 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 "processor.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 TSC_ADJUST_VALUE (1ll << 32)
#define TSC_OFFSET_VALUE -(1ll << 48)
enum {
PORT_ABORT = 0x1000,
PORT_REPORT,
PORT_DONE,
};
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;
static void check_ia32_tsc_adjust(int64_t max)
{
int64_t adjust;
adjust = rdmsr(MSR_IA32_TSC_ADJUST);
GUEST_SYNC(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_pages *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);
GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
GUEST_ASSERT(load_vmcs(vmx_pages));
/* Prepare the VMCS for L2 execution. */
prepare_vmcs(vmx_pages, 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_OFFSETTING;
vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
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);
GUEST_DONE();
}
static void report(int64_t val)
{
pr_info("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_gva;
struct kvm_vcpu *vcpu;
TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX));
vm = vm_create_with_one_vcpu(&vcpu, (void *) l1_guest_code);
/* Allocate VMX pages and shared descriptors (vmx_pages). */
vcpu_alloc_vmx(vm, &vmx_pages_gva);
vcpu_args_set(vcpu, 1, vmx_pages_gva);
for (;;) {
volatile struct kvm_run *run = vcpu->run;
struct ucall uc;
vcpu_run(vcpu);
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));
switch (get_ucall(vcpu, &uc)) {
case UCALL_ABORT:
REPORT_GUEST_ASSERT(uc);
/* NOT REACHED */
case UCALL_SYNC:
report(uc.args[1]);
break;
case UCALL_DONE:
goto done;
default:
TEST_FAIL("Unknown ucall %lu", uc.cmd);
}
}
done:
kvm_vm_free(vm);
return 0;
}
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