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Date: Mon, 14 Jun 2010 21:34:15 -1000
From: Zachary Amsden <zamsden@...hat.com>
To: avi@...hat.com, mtosatti@...hat.com, glommer@...hat.com,
kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Zachary Amsden <zamsden@...hat.com>
Subject: [PATCH 13/17] Add TSC offset tracking
Track the last TSC offset set for each VM and ensure that the storing of
the offset and the reading of the TSC are never preempted by taking a
spinlock.
Signed-off-by: Zachary Amsden <zamsden@...hat.com>
---
arch/x86/include/asm/kvm_host.h | 6 +++++-
arch/x86/kvm/svm.c | 30 +++++++++++++++++-------------
arch/x86/kvm/vmx.c | 21 +++++++--------------
arch/x86/kvm/x86.c | 20 +++++++++++++++++++-
arch/x86/kvm/x86.h | 2 ++
5 files changed, 50 insertions(+), 29 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7ec2472..98d4de8 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -410,8 +410,11 @@ struct kvm_arch {
gpa_t ept_identity_map_addr;
unsigned long irq_sources_bitmap;
- u64 vm_init_tsc;
s64 kvmclock_offset;
+ u64 last_tsc_write;
+ u64 last_tsc_offset;
+ u64 last_tsc_nsec;
+ spinlock_t tsc_write_lock;
struct kvm_xen_hvm_config xen_hvm_config;
@@ -536,6 +539,7 @@ struct kvm_x86_ops {
int (*get_lpage_level)(void);
bool (*rdtscp_supported)(void);
void (*adjust_tsc_offset)(struct kvm_vcpu *vcpu, s64 adjustment);
+ void (*write_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset);
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 ee2cf30..4654507 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2527,20 +2527,9 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 data)
struct vcpu_svm *svm = to_svm(vcpu);
switch (ecx) {
- case MSR_IA32_TSC: {
- u64 tsc_offset = data - native_read_tsc();
- u64 g_tsc_offset = 0;
-
- if (is_nested(svm)) {
- g_tsc_offset = svm->vmcb->control.tsc_offset -
- svm->nested.hsave->control.tsc_offset;
- svm->nested.hsave->control.tsc_offset = tsc_offset;
- }
-
- svm->vmcb->control.tsc_offset = tsc_offset + g_tsc_offset;
-
+ case MSR_IA32_TSC:
+ guest_write_tsc(vcpu, data);
break;
- }
case MSR_K6_STAR:
svm->vmcb->save.star = data;
break;
@@ -3417,6 +3406,20 @@ static void svm_adjust_tsc_offset(struct kvm_vcpu *vcpu, s64 adjustment)
svm->nested.hsave->control.tsc_offset += adjustment;
}
+static void svm_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+ u64 g_tsc_offset = 0;
+
+ if (is_nested(svm)) {
+ g_tsc_offset = svm->vmcb->control.tsc_offset -
+ svm->nested.hsave->control.tsc_offset;
+ svm->nested.hsave->control.tsc_offset = offset;
+ }
+
+ svm->vmcb->control.tsc_offset = offset + g_tsc_offset;
+}
+
static void svm_fpu_deactivate(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -3503,6 +3506,7 @@ static struct kvm_x86_ops svm_x86_ops = {
.set_supported_cpuid = svm_set_supported_cpuid,
.adjust_tsc_offset = svm_adjust_tsc_offset,
+ .write_tsc_offset = svm_write_tsc_offset,
};
static int __init svm_init(void)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index a993e67..9b604b8 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1133,12 +1133,11 @@ static u64 guest_read_tsc(void)
}
/*
- * writes 'guest_tsc' into guest's timestamp counter "register"
- * guest_tsc = host_tsc + tsc_offset ==> tsc_offset = guest_tsc - host_tsc
+ * writes 'offset' into guest's timestamp counter offset register
*/
-static void guest_write_tsc(u64 guest_tsc, u64 host_tsc)
+static void vmx_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
{
- vmcs_write64(TSC_OFFSET, guest_tsc - host_tsc);
+ vmcs_write64(TSC_OFFSET, offset);
}
static void vmx_adjust_tsc_offset(struct kvm_vcpu *vcpu, s64 adjustment)
@@ -1217,7 +1216,6 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
struct shared_msr_entry *msr;
- u64 host_tsc;
int ret = 0;
switch (msr_index) {
@@ -1247,8 +1245,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
vmcs_writel(GUEST_SYSENTER_ESP, data);
break;
case MSR_IA32_TSC:
- rdtscll(host_tsc);
- guest_write_tsc(data, host_tsc);
+ guest_write_tsc(vcpu, data);
break;
case MSR_IA32_CR_PAT:
if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
@@ -2503,7 +2500,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
{
u32 host_sysenter_cs, msr_low, msr_high;
u32 junk;
- u64 host_pat, tsc_this, tsc_base;
+ u64 host_pat;
unsigned long a;
struct desc_ptr dt;
int i;
@@ -2644,12 +2641,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
vmx->vcpu.arch.cr4_guest_owned_bits |= X86_CR4_PGE;
vmcs_writel(CR4_GUEST_HOST_MASK, ~vmx->vcpu.arch.cr4_guest_owned_bits);
- tsc_base = vmx->vcpu.kvm->arch.vm_init_tsc;
- rdtscll(tsc_this);
- if (tsc_this < vmx->vcpu.kvm->arch.vm_init_tsc)
- tsc_base = tsc_this;
-
- guest_write_tsc(0, tsc_base);
+ guest_write_tsc(&vmx->vcpu, 0);
return 0;
}
@@ -4336,6 +4328,7 @@ static struct kvm_x86_ops vmx_x86_ops = {
.set_supported_cpuid = vmx_set_supported_cpuid,
.adjust_tsc_offset = vmx_adjust_tsc_offset,
+ .write_tsc_offset = vmx_write_tsc_offset,
};
static int __init vmx_init(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 15c7317..ef847ee 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -932,6 +932,24 @@ static inline void kvm_request_guest_time_update(struct kvm_vcpu *v)
set_bit(KVM_REQ_CLOCK_SYNC, &v->requests);
}
+void guest_write_tsc(struct kvm_vcpu *vcpu, u64 data)
+{
+ struct kvm *kvm = vcpu->kvm;
+ u64 offset;
+
+ spin_lock(&kvm->arch.tsc_write_lock);
+ offset = data - native_read_tsc();
+ kvm->arch.last_tsc_nsec = get_kernel_ns();
+ kvm->arch.last_tsc_write = data;
+ kvm->arch.last_tsc_offset = offset;
+ kvm_x86_ops->write_tsc_offset(vcpu, offset);
+ spin_unlock(&kvm->arch.tsc_write_lock);
+
+ /* Reset of TSC must disable overshoot protection below */
+ vcpu->arch.hv_clock.tsc_timestamp = 0;
+}
+EXPORT_SYMBOL_GPL(guest_write_tsc);
+
static int kvm_recompute_guest_time(struct kvm_vcpu *v)
{
unsigned long flags;
@@ -5616,7 +5634,7 @@ struct kvm *kvm_arch_create_vm(void)
/* Reserve bit 0 of irq_sources_bitmap for userspace irq source */
set_bit(KVM_USERSPACE_IRQ_SOURCE_ID, &kvm->arch.irq_sources_bitmap);
- rdtscll(kvm->arch.vm_init_tsc);
+ spin_lock_init(&kvm->arch.tsc_write_lock);
return kvm;
}
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index f4b5445..ce2aff8 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -75,4 +75,6 @@ static inline struct kvm_mem_aliases *kvm_aliases(struct kvm *kvm)
void kvm_before_handle_nmi(struct kvm_vcpu *vcpu);
void kvm_after_handle_nmi(struct kvm_vcpu *vcpu);
+void guest_write_tsc(struct kvm_vcpu *vcpu, u64 data);
+
#endif
--
1.7.1
--
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