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Subject[PATCH 2/6] KVM: SVM: Implement infrastructure for TSC_RATE_MSR
Date
This patch enhances the kvm_amd module with functions to
support the TSC_RATE_MSR which can be used to set a given
tsc frequency for the guest vcpu.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---
arch/x86/include/asm/msr-index.h | 1 +
arch/x86/kvm/svm.c | 37 ++++++++++++++++++++++++++++++++++++-
2 files changed, 37 insertions(+), 1 deletions(-)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 5bfafb6..fdac548 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -106,6 +106,7 @@
complete list. */

#define MSR_AMD64_PATCH_LEVEL 0x0000008b
+#define MSR_AMD64_TSC_RATIO 0xc0000104
#define MSR_AMD64_NB_CFG 0xc001001f
#define MSR_AMD64_PATCH_LOADER 0xc0010020
#define MSR_AMD64_OSVW_ID_LENGTH 0xc0010140
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index bfb4948..c96c0a6 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -63,6 +63,8 @@ MODULE_LICENSE("GPL");

#define DEBUGCTL_RESERVED_BITS (~(0x3fULL))

+#define TSC_RATIO_RSVD 0xffffff0000000000ULL
+
static bool erratum_383_found __read_mostly;

static const u32 host_save_user_msrs[] = {
@@ -142,6 +144,12 @@ struct vcpu_svm {
unsigned int3_injected;
unsigned long int3_rip;
u32 apf_reason;
+
+ struct {
+ bool enabled;
+ u64 ratio;
+ } tsc_scale;
+
};

#define MSR_INVALID 0xffffffffU
@@ -852,6 +860,25 @@ static void init_sys_seg(struct vmcb_seg *seg, uint32_t type)
seg->base = 0;
}

+static u64 svm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+ u64 _tsc = tsc;
+
+ if (svm->tsc_scale.enabled) {
+ u64 mult, frac;
+
+ mult = svm->tsc_scale.ratio >> 32;
+ frac = svm->tsc_scale.ratio & ((1ULL << 32) - 1);
+
+ _tsc *= mult;
+ _tsc += (tsc >> 32) * frac;
+ _tsc += ((tsc & ((1ULL << 32) - 1)) * frac) >> 32;
+ }
+
+ return _tsc;
+}
+
static void svm_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -2808,7 +2835,9 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 *data)
case MSR_IA32_TSC: {
struct vmcb *vmcb = get_host_vmcb(svm);

- *data = vmcb->control.tsc_offset + native_read_tsc();
+ *data = vmcb->control.tsc_offset +
+ svm_scale_tsc(vcpu, native_read_tsc());
+
break;
}
case MSR_STAR:
@@ -3564,6 +3593,9 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)

clgi();

+ if (static_cpu_has(X86_FEATURE_TSCRATEMSR) && svm->tsc_scale.enabled)
+ wrmsrl(MSR_AMD64_TSC_RATIO, svm->tsc_scale.ratio);
+
local_irq_enable();

asm volatile (
@@ -3647,6 +3679,9 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)

local_irq_disable();

+ if (static_cpu_has(X86_FEATURE_TSCRATEMSR) && svm->tsc_scale.enabled)
+ wrmsr(MSR_AMD64_TSC_RATIO, 0, 1);
+
vcpu->arch.cr2 = svm->vmcb->save.cr2;
vcpu->arch.regs[VCPU_REGS_RAX] = svm->vmcb->save.rax;
vcpu->arch.regs[VCPU_REGS_RSP] = svm->vmcb->save.rsp;
--
1.7.1



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