KVM: x86: Unify TSC logic
Move the TSC control logic from the vendor backends into x86.c
by adding adjust_tsc_offset to x86 ops. Now all TSC decisions
can be done in one place.
Signed-off-by: Zachary Amsden <zamsden@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 57b4394..5ab1c3f 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -255,7 +255,6 @@
};
struct kvm_vcpu_arch {
- u64 host_tsc;
/*
* rip and regs accesses must go through
* kvm_{register,rip}_{read,write} functions.
@@ -336,9 +335,10 @@
gpa_t time;
struct pvclock_vcpu_time_info hv_clock;
- unsigned int hv_clock_tsc_khz;
+ unsigned int hw_tsc_khz;
unsigned int time_offset;
struct page *time_page;
+ u64 last_host_tsc;
bool nmi_pending;
bool nmi_injected;
@@ -520,6 +520,7 @@
u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
int (*get_lpage_level)(void);
bool (*rdtscp_supported)(void);
+ void (*adjust_tsc_offset)(struct kvm_vcpu *vcpu, s64 adjustment);
void (*set_supported_cpuid)(u32 func, struct kvm_cpuid_entry2 *entry);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index ea41c55..ff28f65 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -715,6 +715,15 @@
svm->vmcb->control.tsc_offset = offset + g_tsc_offset;
}
+static void svm_adjust_tsc_offset(struct kvm_vcpu *vcpu, s64 adjustment)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ svm->vmcb->control.tsc_offset += adjustment;
+ if (is_nested(svm))
+ svm->nested.hsave->control.tsc_offset += adjustment;
+}
+
static void init_vmcb(struct vcpu_svm *svm)
{
struct vmcb_control_area *control = &svm->vmcb->control;
@@ -961,20 +970,6 @@
int i;
if (unlikely(cpu != vcpu->cpu)) {
- u64 delta;
-
- if (check_tsc_unstable()) {
- /*
- * Make sure that the guest sees a monotonically
- * increasing TSC.
- */
- delta = vcpu->arch.host_tsc - native_read_tsc();
- svm->vmcb->control.tsc_offset += delta;
- if (is_nested(svm))
- svm->nested.hsave->control.tsc_offset += delta;
- }
- vcpu->cpu = cpu;
- kvm_migrate_timers(vcpu);
svm->asid_generation = 0;
}
@@ -990,8 +985,6 @@
++vcpu->stat.host_state_reload;
for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)
wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
-
- vcpu->arch.host_tsc = native_read_tsc();
}
static unsigned long svm_get_rflags(struct kvm_vcpu *vcpu)
@@ -3553,6 +3546,7 @@
.has_wbinvd_exit = svm_has_wbinvd_exit,
.write_tsc_offset = svm_write_tsc_offset,
+ .adjust_tsc_offset = svm_adjust_tsc_offset,
};
static int __init svm_init(void)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 138746d..275a81d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -505,7 +505,6 @@
vmcs_clear(vmx->vmcs);
if (per_cpu(current_vmcs, cpu) == vmx->vmcs)
per_cpu(current_vmcs, cpu) = NULL;
- rdtscll(vmx->vcpu.arch.host_tsc);
list_del(&vmx->local_vcpus_link);
vmx->vcpu.cpu = -1;
vmx->launched = 0;
@@ -881,7 +880,6 @@
static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- u64 tsc_this, delta, new_offset;
u64 phys_addr = __pa(per_cpu(vmxarea, cpu));
if (!vmm_exclusive)
@@ -898,14 +896,12 @@
struct desc_ptr *gdt = &__get_cpu_var(host_gdt);
unsigned long sysenter_esp;
- kvm_migrate_timers(vcpu);
kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
local_irq_disable();
list_add(&vmx->local_vcpus_link,
&per_cpu(vcpus_on_cpu, cpu));
local_irq_enable();
- vcpu->cpu = cpu;
/*
* Linux uses per-cpu TSS and GDT, so set these when switching
* processors.
@@ -915,16 +911,6 @@
rdmsrl(MSR_IA32_SYSENTER_ESP, sysenter_esp);
vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */
-
- /*
- * Make sure the time stamp counter is monotonous.
- */
- rdtscll(tsc_this);
- if (tsc_this < vcpu->arch.host_tsc) {
- delta = vcpu->arch.host_tsc - tsc_this;
- new_offset = vmcs_read64(TSC_OFFSET) + delta;
- vmcs_write64(TSC_OFFSET, new_offset);
- }
}
}
@@ -1153,6 +1139,12 @@
vmcs_write64(TSC_OFFSET, offset);
}
+static void vmx_adjust_tsc_offset(struct kvm_vcpu *vcpu, s64 adjustment)
+{
+ u64 offset = vmcs_read64(TSC_OFFSET);
+ vmcs_write64(TSC_OFFSET, offset + adjustment);
+}
+
/*
* Reads an msr value (of 'msr_index') into 'pdata'.
* Returns 0 on success, non-0 otherwise.
@@ -4108,6 +4100,7 @@
cpu = get_cpu();
vmx_vcpu_load(&vmx->vcpu, cpu);
+ vmx->vcpu.cpu = cpu;
err = vmx_vcpu_setup(vmx);
vmx_vcpu_put(&vmx->vcpu);
put_cpu();
@@ -4347,6 +4340,7 @@
.has_wbinvd_exit = cpu_has_vmx_wbinvd_exit,
.write_tsc_offset = vmx_write_tsc_offset,
+ .adjust_tsc_offset = vmx_adjust_tsc_offset,
};
static int __init vmx_init(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a8dee58..468fafa 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -973,9 +973,9 @@
return 1;
}
- if (unlikely(vcpu->hv_clock_tsc_khz != this_tsc_khz)) {
+ if (unlikely(vcpu->hw_tsc_khz != this_tsc_khz)) {
kvm_set_time_scale(this_tsc_khz, &vcpu->hv_clock);
- vcpu->hv_clock_tsc_khz = this_tsc_khz;
+ vcpu->hw_tsc_khz = this_tsc_khz;
}
/* With all the info we got, fill in the values */
@@ -1866,13 +1866,24 @@
}
kvm_x86_ops->vcpu_load(vcpu, cpu);
- kvm_request_guest_time_update(vcpu);
+ if (unlikely(vcpu->cpu != cpu)) {
+ /* Make sure TSC doesn't go backwards */
+ s64 tsc_delta = !vcpu->arch.last_host_tsc ? 0 :
+ native_read_tsc() - vcpu->arch.last_host_tsc;
+ if (tsc_delta < 0)
+ mark_tsc_unstable("KVM discovered backwards TSC");
+ if (check_tsc_unstable())
+ kvm_x86_ops->adjust_tsc_offset(vcpu, -tsc_delta);
+ kvm_migrate_timers(vcpu);
+ vcpu->cpu = cpu;
+ }
}
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
kvm_x86_ops->vcpu_put(vcpu);
kvm_put_guest_fpu(vcpu);
+ vcpu->arch.last_host_tsc = native_read_tsc();
}
static int is_efer_nx(void)