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| author | Anthony Liguori <aliguori@us.ibm.com> | 2007-04-29 11:56:06 +0300 |
|---|---|---|
| committer | Avi Kivity <avi@qumranet.com> | 2007-05-03 10:52:32 +0300 |
| commit | 94dfbdb3894eda2f673b70e20da2743c4a8d3968 (patch) | |
| tree | 74e7a4a31a72ed0e3753e9390189d2e8132ecf0e /drivers/kvm/svm.c | |
| parent | 2807696c3791d6dd1dcf20f022eaa2dc7615bc5d (diff) | |
| download | lwn-94dfbdb3894eda2f673b70e20da2743c4a8d3968.tar.gz lwn-94dfbdb3894eda2f673b70e20da2743c4a8d3968.zip | |
KVM: SVM: Only save/restore MSRs when needed
We only have to save/restore MSR_GS_BASE on every VMEXIT. The rest can be
saved/restored when we leave the VCPU. Since we don't emulate the DEBUGCTL
MSRs and the guest cannot write to them, we don't have to worry about
saving/restoring them at all.
This shaves a whopping 40% off raw vmexit costs on AMD.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'drivers/kvm/svm.c')
| -rw-r--r-- | drivers/kvm/svm.c | 26 |
1 files changed, 15 insertions, 11 deletions
diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c index bddd0238869d..9c15f32eea18 100644 --- a/drivers/kvm/svm.c +++ b/drivers/kvm/svm.c @@ -522,8 +522,6 @@ static void init_vmcb(struct vmcb *vmcb) control->msrpm_base_pa = msrpm_base; control->tsc_offset = 0; control->int_ctl = V_INTR_MASKING_MASK; - if (svm_has(SVM_FEATURE_LBRV)) - control->lbr_ctl = 1ULL; init_seg(&save->es); init_seg(&save->ss); @@ -611,7 +609,7 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu) static void svm_vcpu_load(struct kvm_vcpu *vcpu) { - int cpu; + int cpu, i; cpu = get_cpu(); if (unlikely(cpu != vcpu->cpu)) { @@ -626,10 +624,18 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu) vcpu->svm->vmcb->control.tsc_offset += delta; vcpu->cpu = cpu; } + + for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++) + rdmsrl(host_save_user_msrs[i], vcpu->svm->host_user_msrs[i]); } static void svm_vcpu_put(struct kvm_vcpu *vcpu) { + int i; + + for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++) + wrmsrl(host_save_user_msrs[i], vcpu->svm->host_user_msrs[i]); + rdtscll(vcpu->host_tsc); put_cpu(); } @@ -815,18 +821,16 @@ static int svm_guest_debug(struct kvm_vcpu *vcpu, struct kvm_debug_guest *dbg) static void load_host_msrs(struct kvm_vcpu *vcpu) { - int i; - - for ( i = 0; i < NR_HOST_SAVE_MSRS; i++) - wrmsrl(host_save_msrs[i], vcpu->svm->host_msrs[i]); +#ifdef CONFIG_X86_64 + wrmsrl(MSR_GS_BASE, vcpu->svm->host_gs_base); +#endif } static void save_host_msrs(struct kvm_vcpu *vcpu) { - int i; - - for ( i = 0; i < NR_HOST_SAVE_MSRS; i++) - rdmsrl(host_save_msrs[i], vcpu->svm->host_msrs[i]); +#ifdef CONFIG_X86_64 + rdmsrl(MSR_GS_BASE, vcpu->svm->host_gs_base); +#endif } static void new_asid(struct kvm_vcpu *vcpu, struct svm_cpu_data *svm_data) |