KVM: x86: Set intercept for Intel PT MSRs read/write

To save performance overhead, disable intercept Intel PT MSRs
read/write when Intel PT is enabled in guest.
MSR_IA32_RTIT_CTL is an exception that will always be intercepted.

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Signed-off-by: Luwei Kang <luwei.kang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a4ec536..338c650 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -977,15 +977,11 @@ static void pt_guest_enter(struct vcpu_vmx *vmx)
        if (pt_mode == PT_MODE_SYSTEM)
                return;
 
-       /* Save host state before VM entry */
-       rdmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl);
-
        /*
-        * Set guest state of MSR_IA32_RTIT_CTL MSR (PT will be disabled
-        * on VM entry when it has been disabled in guest before).
+        * GUEST_IA32_RTIT_CTL is already set in the VMCS.
+        * Save host state before VM entry.
         */
-       vmcs_write64(GUEST_IA32_RTIT_CTL, vmx->pt_desc.guest.ctl);
-
+       rdmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl);
        if (vmx->pt_desc.guest.ctl & RTIT_CTL_TRACEEN) {
                wrmsrl(MSR_IA32_RTIT_CTL, 0);
                pt_save_msr(&vmx->pt_desc.host, vmx->pt_desc.addr_range);
@@ -1934,6 +1930,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
                        return 1;
                vmcs_write64(GUEST_IA32_RTIT_CTL, data);
                vmx->pt_desc.guest.ctl = data;
+               pt_update_intercept_for_msr(vmx);
                break;
        case MSR_IA32_RTIT_STATUS:
                if ((pt_mode != PT_MODE_HOST_GUEST) ||
@@ -3567,6 +3564,28 @@ void vmx_update_msr_bitmap(struct kvm_vcpu *vcpu)
        vmx->msr_bitmap_mode = mode;
 }
 
+void pt_update_intercept_for_msr(struct vcpu_vmx *vmx)
+{
+       unsigned long *msr_bitmap = vmx->vmcs01.msr_bitmap;
+       bool flag = !(vmx->pt_desc.guest.ctl & RTIT_CTL_TRACEEN);
+       u32 i;
+
+       vmx_set_intercept_for_msr(msr_bitmap, MSR_IA32_RTIT_STATUS,
+                                                       MSR_TYPE_RW, flag);
+       vmx_set_intercept_for_msr(msr_bitmap, MSR_IA32_RTIT_OUTPUT_BASE,
+                                                       MSR_TYPE_RW, flag);
+       vmx_set_intercept_for_msr(msr_bitmap, MSR_IA32_RTIT_OUTPUT_MASK,
+                                                       MSR_TYPE_RW, flag);
+       vmx_set_intercept_for_msr(msr_bitmap, MSR_IA32_RTIT_CR3_MATCH,
+                                                       MSR_TYPE_RW, flag);
+       for (i = 0; i < vmx->pt_desc.addr_range; i++) {
+               vmx_set_intercept_for_msr(msr_bitmap,
+                       MSR_IA32_RTIT_ADDR0_A + i * 2, MSR_TYPE_RW, flag);
+               vmx_set_intercept_for_msr(msr_bitmap,
+                       MSR_IA32_RTIT_ADDR0_B + i * 2, MSR_TYPE_RW, flag);
+       }
+}
+
 static bool vmx_get_enable_apicv(struct kvm_vcpu *vcpu)
 {
        return enable_apicv;

diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index dd3b9ab..20172c1 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -316,6 +316,7 @@ bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu);
 void vmx_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked);
 void vmx_set_virtual_apic_mode(struct kvm_vcpu *vcpu);
 struct shared_msr_entry *find_msr_entry(struct vcpu_vmx *vmx, u32 msr);
+void pt_update_intercept_for_msr(struct vcpu_vmx *vmx);
 
 #define POSTED_INTR_ON  0
 #define POSTED_INTR_SN  1