From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
When switching between vmcs01 and vmcs02, there is no need to update
state tracking for values that aren't tied to any particular VMCS as
the per-vCPU values are already up-to-date (vmx_switch_vmcs() can only
be called when the vCPU is loaded).
Avoiding the update eliminates a RDMSR, and potentially a RDPKRU and
posted-interrupt updated (cmpxchg64() and more).
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 2 +-
arch/x86/kvm/vmx/vmx.c | 18 +++++++++++++-----
arch/x86/kvm/vmx/vmx.h | 1 +
3 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index f4415756ddd5..9478d8947595 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -279,7 +279,7 @@ static void vmx_switch_vmcs(struct kvm_vcpu *vcpu, struct loaded_vmcs *vmcs)
cpu = get_cpu();
prev = vmx->loaded_vmcs;
vmx->loaded_vmcs = vmcs;
- vmx_vcpu_load(vcpu, cpu);
+ vmx_vcpu_load_vmcs(vcpu, cpu);
vmx_sync_vmcs_host_state(vmx, prev);
put_cpu();
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 09632b8239de..7a2d9a4b828c 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1234,11 +1234,7 @@ static void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
pi_set_on(pi_desc);
}
-/*
- * Switches to specified vcpu, until a matching vcpu_put(), but assumes
- * vcpu mutex is already taken.
- */
-void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
+void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
bool already_loaded = vmx->loaded_vmcs->cpu == cpu;
@@ -1299,8 +1295,20 @@ void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
if (kvm_has_tsc_control &&
vmx->current_tsc_ratio != vcpu->arch.tsc_scaling_ratio)
decache_tsc_multiplier(vmx);
+}
+
+/*
+ * Switches to specified vcpu, until a matching vcpu_put(), but assumes
+ * vcpu mutex is already taken.
+ */
+void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+ vmx_vcpu_load_vmcs(vcpu, cpu);
vmx_vcpu_pi_load(vcpu, cpu);
+
vmx->host_pkru = read_pkru();
vmx->host_debugctlmsr = get_debugctlmsr();
}
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 581f4039b346..36a2056fafd4 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -302,6 +302,7 @@ struct kvm_vmx {
};
bool nested_vmx_allowed(struct kvm_vcpu *vcpu);
+void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu);
void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
int allocate_vpid(void);
void free_vpid(int vpid);
--
1.8.3.1
