Ensure that the storing of the offset and the reading of the TSC are never preempted by taking a spinlock. While the lock is overkill now, it is useful later in this patch series.
Signed-off-by: Zachary Amsden <[email protected]> --- arch/x86/include/asm/kvm_host.h | 4 +++- arch/x86/kvm/svm.c | 31 ++++++++++++++++++------------- arch/x86/kvm/vmx.c | 22 ++++++++-------------- arch/x86/kvm/x86.c | 17 ++++++++++++++++- arch/x86/kvm/x86.h | 2 ++ 5 files changed, 47 insertions(+), 29 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 502e53f..3b4efe2 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -394,8 +394,8 @@ struct kvm_arch { gpa_t ept_identity_map_addr; unsigned long irq_sources_bitmap; - u64 vm_init_tsc; s64 kvmclock_offset; + spinlock_t tsc_write_lock; struct kvm_xen_hvm_config xen_hvm_config; @@ -522,6 +522,8 @@ struct kvm_x86_ops { bool (*has_wbinvd_exit)(void); + void (*write_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset); + const struct trace_print_flags *exit_reasons_str; }; diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 56c9b6b..6671053 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -2543,20 +2543,9 @@ 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; @@ -3429,6 +3418,20 @@ static bool svm_has_wbinvd_exit(void) return true; } +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); @@ -3515,6 +3518,8 @@ static struct kvm_x86_ops svm_x86_ops = { .set_supported_cpuid = svm_set_supported_cpuid, .has_wbinvd_exit = svm_has_wbinvd_exit, + + .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 2fdcc98..9055ca6 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1153,12 +1153,11 @@ 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); } /* @@ -1231,7 +1230,6 @@ 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) { @@ -1261,8 +1259,7 @@ 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) { @@ -2517,7 +2514,7 @@ 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; @@ -2658,12 +2655,7 @@ 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; } @@ -4358,6 +4350,8 @@ static struct kvm_x86_ops vmx_x86_ops = { .set_supported_cpuid = vmx_set_supported_cpuid, .has_wbinvd_exit = cpu_has_vmx_wbinvd_exit, + + .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 6ed3176..a2ee975 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -893,6 +893,21 @@ static void kvm_set_time_scale(uint32_t tsc_khz, struct pvclock_vcpu_time_info * static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz); +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_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 void kvm_write_guest_time(struct kvm_vcpu *v) { struct timespec ts; @@ -5487,7 +5502,7 @@ 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 b7a4047..f8d81f4 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -68,4 +68,6 @@ static inline int is_paging(struct kvm_vcpu *vcpu) 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 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
