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-rw-r--r--arch/x86/kvm/x86.c30
-rw-r--r--tools/testing/selftests/kvm/Makefile1
-rw-r--r--tools/testing/selftests/kvm/x86_64/tsc_msrs_test.c168
3 files changed, 179 insertions, 20 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 411f6103532b..c4015a43cc8a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2107,12 +2107,6 @@ static void kvm_track_tsc_matching(struct kvm_vcpu *vcpu)
#endif
}
-static void update_ia32_tsc_adjust_msr(struct kvm_vcpu *vcpu, s64 offset)
-{
- u64 curr_offset = vcpu->arch.l1_tsc_offset;
- vcpu->arch.ia32_tsc_adjust_msr += offset - curr_offset;
-}
-
/*
* Multiply tsc by a fixed point number represented by ratio.
*
@@ -2174,14 +2168,13 @@ static inline bool kvm_check_tsc_unstable(void)
return check_tsc_unstable();
}
-void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
+static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 data)
{
struct kvm *kvm = vcpu->kvm;
u64 offset, ns, elapsed;
unsigned long flags;
bool matched;
bool already_matched;
- u64 data = msr->data;
bool synchronizing = false;
raw_spin_lock_irqsave(&kvm->arch.tsc_write_lock, flags);
@@ -2190,7 +2183,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
elapsed = ns - kvm->arch.last_tsc_nsec;
if (vcpu->arch.virtual_tsc_khz) {
- if (data == 0 && msr->host_initiated) {
+ if (data == 0) {
/*
* detection of vcpu initialization -- need to sync
* with other vCPUs. This particularly helps to keep
@@ -2260,9 +2253,6 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
vcpu->arch.this_tsc_nsec = kvm->arch.cur_tsc_nsec;
vcpu->arch.this_tsc_write = kvm->arch.cur_tsc_write;
- if (!msr->host_initiated && guest_cpuid_has(vcpu, X86_FEATURE_TSC_ADJUST))
- update_ia32_tsc_adjust_msr(vcpu, offset);
-
kvm_vcpu_write_tsc_offset(vcpu, offset);
raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
@@ -2277,8 +2267,6 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
spin_unlock(&kvm->arch.pvclock_gtod_sync_lock);
}
-EXPORT_SYMBOL_GPL(kvm_write_tsc);
-
static inline void adjust_tsc_offset_guest(struct kvm_vcpu *vcpu,
s64 adjustment)
{
@@ -3073,7 +3061,13 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
vcpu->arch.msr_ia32_power_ctl = data;
break;
case MSR_IA32_TSC:
- kvm_write_tsc(vcpu, msr_info);
+ if (msr_info->host_initiated) {
+ kvm_synchronize_tsc(vcpu, data);
+ } else {
+ u64 adj = kvm_compute_tsc_offset(vcpu, data) - vcpu->arch.l1_tsc_offset;
+ adjust_tsc_offset_guest(vcpu, adj);
+ vcpu->arch.ia32_tsc_adjust_msr += adj;
+ }
break;
case MSR_IA32_XSS:
if (!msr_info->host_initiated &&
@@ -9839,7 +9833,6 @@ fail_mmu_destroy:
void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
{
- struct msr_data msr;
struct kvm *kvm = vcpu->kvm;
kvm_hv_vcpu_postcreate(vcpu);
@@ -9847,10 +9840,7 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
if (mutex_lock_killable(&vcpu->mutex))
return;
vcpu_load(vcpu);
- msr.data = 0x0;
- msr.index = MSR_IA32_TSC;
- msr.host_initiated = true;
- kvm_write_tsc(vcpu, &msr);
+ kvm_synchronize_tsc(vcpu, 0);
vcpu_put(vcpu);
/* poll control enabled by default */
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 80d5c348354c..7ebe71fbca53 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -55,6 +55,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test
TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
TEST_GEN_PROGS_x86_64 += x86_64/debug_regs
+TEST_GEN_PROGS_x86_64 += x86_64/tsc_msrs_test
TEST_GEN_PROGS_x86_64 += x86_64/user_msr_test
TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
TEST_GEN_PROGS_x86_64 += demand_paging_test
diff --git a/tools/testing/selftests/kvm/x86_64/tsc_msrs_test.c b/tools/testing/selftests/kvm/x86_64/tsc_msrs_test.c
new file mode 100644
index 000000000000..f8e761149daa
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/tsc_msrs_test.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Tests for MSR_IA32_TSC and MSR_IA32_TSC_ADJUST.
+ *
+ * Copyright (C) 2020, Red Hat, Inc.
+ */
+#include <stdio.h>
+#include <string.h>
+#include "kvm_util.h"
+#include "processor.h"
+
+#define VCPU_ID 0
+
+#define UNITY (1ull << 30)
+#define HOST_ADJUST (UNITY * 64)
+#define GUEST_STEP (UNITY * 4)
+#define ROUND(x) ((x + UNITY / 2) & -UNITY)
+#define rounded_rdmsr(x) ROUND(rdmsr(x))
+#define rounded_host_rdmsr(x) ROUND(vcpu_get_msr(vm, 0, x))
+
+#define GUEST_ASSERT_EQ(a, b) do { \
+ __typeof(a) _a = (a); \
+ __typeof(b) _b = (b); \
+ if (_a != _b) \
+ ucall(UCALL_ABORT, 4, \
+ "Failed guest assert: " \
+ #a " == " #b, __LINE__, _a, _b); \
+ } while(0)
+
+static void guest_code(void)
+{
+ u64 val = 0;
+
+ GUEST_ASSERT_EQ(rounded_rdmsr(MSR_IA32_TSC), val);
+ GUEST_ASSERT_EQ(rounded_rdmsr(MSR_IA32_TSC_ADJUST), val);
+
+ /* Guest: writes to MSR_IA32_TSC affect both MSRs. */
+ val = 1ull * GUEST_STEP;
+ wrmsr(MSR_IA32_TSC, val);
+ GUEST_ASSERT_EQ(rounded_rdmsr(MSR_IA32_TSC), val);
+ GUEST_ASSERT_EQ(rounded_rdmsr(MSR_IA32_TSC_ADJUST), val);
+
+ /* Guest: writes to MSR_IA32_TSC_ADJUST affect both MSRs. */
+ GUEST_SYNC(2);
+ val = 2ull * GUEST_STEP;
+ wrmsr(MSR_IA32_TSC_ADJUST, val);
+ GUEST_ASSERT_EQ(rounded_rdmsr(MSR_IA32_TSC), val);
+ GUEST_ASSERT_EQ(rounded_rdmsr(MSR_IA32_TSC_ADJUST), val);
+
+ /* Host: setting the TSC offset. */
+ GUEST_SYNC(3);
+ GUEST_ASSERT_EQ(rounded_rdmsr(MSR_IA32_TSC), HOST_ADJUST + val);
+ GUEST_ASSERT_EQ(rounded_rdmsr(MSR_IA32_TSC_ADJUST), val);
+
+ /*
+ * Guest: writes to MSR_IA32_TSC_ADJUST do not destroy the
+ * host-side offset and affect both MSRs.
+ */
+ GUEST_SYNC(4);
+ val = 3ull * GUEST_STEP;
+ wrmsr(MSR_IA32_TSC_ADJUST, val);
+ GUEST_ASSERT_EQ(rounded_rdmsr(MSR_IA32_TSC), HOST_ADJUST + val);
+ GUEST_ASSERT_EQ(rounded_rdmsr(MSR_IA32_TSC_ADJUST), val);
+
+ /*
+ * Guest: writes to MSR_IA32_TSC affect both MSRs, so the host-side
+ * offset is now visible in MSR_IA32_TSC_ADJUST.
+ */
+ GUEST_SYNC(5);
+ val = 4ull * GUEST_STEP;
+ wrmsr(MSR_IA32_TSC, val);
+ GUEST_ASSERT_EQ(rounded_rdmsr(MSR_IA32_TSC), val);
+ GUEST_ASSERT_EQ(rounded_rdmsr(MSR_IA32_TSC_ADJUST), val - HOST_ADJUST);
+
+ GUEST_DONE();
+}
+
+static void run_vcpu(struct kvm_vm *vm, uint32_t vcpuid, int stage)
+{
+ struct ucall uc;
+
+ vcpu_args_set(vm, vcpuid, 1, vcpuid);
+
+ vcpu_ioctl(vm, vcpuid, KVM_RUN, NULL);
+
+ switch (get_ucall(vm, vcpuid, &uc)) {
+ case UCALL_SYNC:
+ TEST_ASSERT(!strcmp((const char *)uc.args[0], "hello") &&
+ uc.args[1] == stage + 1, "Stage %d: Unexpected register values vmexit, got %lx",
+ stage + 1, (ulong)uc.args[1]);
+ return;
+ case UCALL_DONE:
+ return;
+ case UCALL_ABORT:
+ TEST_ASSERT(false, "%s at %s:%ld\n" \
+ "\tvalues: %#lx, %#lx", (const char *)uc.args[0],
+ __FILE__, uc.args[1], uc.args[2], uc.args[3]);
+ default:
+ TEST_ASSERT(false, "Unexpected exit: %s",
+ exit_reason_str(vcpu_state(vm, vcpuid)->exit_reason));
+ }
+}
+
+int main(void)
+{
+ struct kvm_vm *vm;
+ uint64_t val;
+
+ vm = vm_create_default(VCPU_ID, 0, guest_code);
+ vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
+
+ val = 0;
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC), val);
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC_ADJUST), val);
+
+ /* Guest: writes to MSR_IA32_TSC affect both MSRs. */
+ run_vcpu(vm, VCPU_ID, 1);
+ val = 1ull * GUEST_STEP;
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC), val);
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC_ADJUST), val);
+
+ /* Guest: writes to MSR_IA32_TSC_ADJUST affect both MSRs. */
+ run_vcpu(vm, VCPU_ID, 2);
+ val = 2ull * GUEST_STEP;
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC), val);
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC_ADJUST), val);
+
+ /*
+ * Host: writes to MSR_IA32_TSC set the host-side offset
+ * and therefore do not change MSR_IA32_TSC_ADJUST.
+ */
+ vcpu_set_msr(vm, 0, MSR_IA32_TSC, HOST_ADJUST + val);
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC), HOST_ADJUST + val);
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC_ADJUST), val);
+ run_vcpu(vm, VCPU_ID, 3);
+
+ /* Host: writes to MSR_IA32_TSC_ADJUST do not modify the TSC. */
+ vcpu_set_msr(vm, 0, MSR_IA32_TSC_ADJUST, UNITY * 123456);
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC), HOST_ADJUST + val);
+ ASSERT_EQ(vcpu_get_msr(vm, 0, MSR_IA32_TSC_ADJUST), UNITY * 123456);
+
+ /* Restore previous value. */
+ vcpu_set_msr(vm, 0, MSR_IA32_TSC_ADJUST, val);
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC), HOST_ADJUST + val);
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC_ADJUST), val);
+
+ /*
+ * Guest: writes to MSR_IA32_TSC_ADJUST do not destroy the
+ * host-side offset and affect both MSRs.
+ */
+ run_vcpu(vm, VCPU_ID, 4);
+ val = 3ull * GUEST_STEP;
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC), HOST_ADJUST + val);
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC_ADJUST), val);
+
+ /*
+ * Guest: writes to MSR_IA32_TSC affect both MSRs, so the host-side
+ * offset is now visible in MSR_IA32_TSC_ADJUST.
+ */
+ run_vcpu(vm, VCPU_ID, 5);
+ val = 4ull * GUEST_STEP;
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC), val);
+ ASSERT_EQ(rounded_host_rdmsr(MSR_IA32_TSC_ADJUST), val - HOST_ADJUST);
+
+ kvm_vm_free(vm);
+
+ return 0;
+}
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