1 files changed, 41 insertions, 10 deletions

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 39d280e7e80e..96bab464967f 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -28,6 +28,7 @@
 #include "cpuid.h"
 #include "lapic.h"
 #include "svm.h"
+#include "hyperv.h"
 
 #define CC KVM_NESTED_VMENTER_CONSISTENCY_CHECK
 
@@ -165,14 +166,30 @@ void recalc_intercepts(struct vcpu_svm *svm)
 	vmcb_set_intercept(c, INTERCEPT_VMSAVE);
 }
 
+/*
+ * Merge L0's (KVM) and L1's (Nested VMCB) MSR permission bitmaps. The function
+ * is optimized in that it only merges the parts where KVM MSR permission bitmap
+ * may contain zero bits.
+ */
 static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm)
 {
+	struct hv_enlightenments *hve =
+		(struct hv_enlightenments *)svm->nested.ctl.reserved_sw;
+	int i;
+
 	/*
-	 * This function merges the msr permission bitmaps of kvm and the
-	 * nested vmcb. It is optimized in that it only merges the parts where
-	 * the kvm msr permission bitmap may contain zero bits
+	 * MSR bitmap update can be skipped when:
+	 * - MSR bitmap for L1 hasn't changed.
+	 * - Nested hypervisor (L1) is attempting to launch the same L2 as
+	 *   before.
+	 * - Nested hypervisor (L1) is using Hyper-V emulation interface and
+	 * tells KVM (L0) there were no changes in MSR bitmap for L2.
 	 */
-	int i;
+	if (!svm->nested.force_msr_bitmap_recalc &&
+	    kvm_hv_hypercall_enabled(&svm->vcpu) &&
+	    hve->hv_enlightenments_control.msr_bitmap &&
+	    (svm->nested.ctl.clean & BIT(VMCB_HV_NESTED_ENLIGHTENMENTS)))
+		goto set_msrpm_base_pa;
 
 	if (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT)))
 		return true;
@@ -193,6 +210,9 @@ static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm)
 		svm->nested.msrpm[p] = svm->msrpm[p] | value;
 	}
 
+	svm->nested.force_msr_bitmap_recalc = false;
+
+set_msrpm_base_pa:
 	svm->vmcb->control.msrpm_base_pa = __sme_set(__pa(svm->nested.msrpm));
 
 	return true;
@@ -298,7 +318,8 @@ static bool nested_vmcb_check_controls(struct kvm_vcpu *vcpu)
 }
 
 static
-void __nested_copy_vmcb_control_to_cache(struct vmcb_ctrl_area_cached *to,
+void __nested_copy_vmcb_control_to_cache(struct kvm_vcpu *vcpu,
+					 struct vmcb_ctrl_area_cached *to,
 					 struct vmcb_control_area *from)
 {
 	unsigned int i;
@@ -331,12 +352,19 @@ void __nested_copy_vmcb_control_to_cache(struct vmcb_ctrl_area_cached *to,
 	to->asid           = from->asid;
 	to->msrpm_base_pa &= ~0x0fffULL;
 	to->iopm_base_pa  &= ~0x0fffULL;
+
+	/* Hyper-V extensions (Enlightened VMCB) */
+	if (kvm_hv_hypercall_enabled(vcpu)) {
+		to->clean = from->clean;
+		memcpy(to->reserved_sw, from->reserved_sw,
+		       sizeof(struct hv_enlightenments));
+	}
 }
 
 void nested_copy_vmcb_control_to_cache(struct vcpu_svm *svm,
 				       struct vmcb_control_area *control)
 {
-	__nested_copy_vmcb_control_to_cache(&svm->nested.ctl, control);
+	__nested_copy_vmcb_control_to_cache(&svm->vcpu, &svm->nested.ctl, control);
 }
 
 static void __nested_copy_vmcb_save_to_cache(struct vmcb_save_area_cached *to,
@@ -464,14 +492,14 @@ static int nested_svm_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
 	    CC(!load_pdptrs(vcpu, cr3)))
 		return -EINVAL;
 
-	if (!nested_npt)
-		kvm_mmu_new_pgd(vcpu, cr3);
-
 	vcpu->arch.cr3 = cr3;
 
 	/* Re-initialize the MMU, e.g. to pick up CR4 MMU role changes. */
 	kvm_init_mmu(vcpu);
 
+	if (!nested_npt)
+		kvm_mmu_new_pgd(vcpu, cr3);
+
 	return 0;
 }
 
@@ -494,6 +522,7 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12
 	if (svm->nested.vmcb12_gpa != svm->nested.last_vmcb12_gpa) {
 		new_vmcb12 = true;
 		svm->nested.last_vmcb12_gpa = svm->nested.vmcb12_gpa;
+		svm->nested.force_msr_bitmap_recalc = true;
 	}
 
 	if (unlikely(new_vmcb12 || vmcb_is_dirty(vmcb12, VMCB_SEG))) {
@@ -1302,6 +1331,7 @@ static void nested_copy_vmcb_cache_to_control(struct vmcb_control_area *dst,
 	dst->virt_ext              = from->virt_ext;
 	dst->pause_filter_count   = from->pause_filter_count;
 	dst->pause_filter_thresh  = from->pause_filter_thresh;
+	/* 'clean' and 'reserved_sw' are not changed by KVM */
 }
 
 static int svm_get_nested_state(struct kvm_vcpu *vcpu,
@@ -1434,7 +1464,7 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
 		goto out_free;
 
 	ret = -EINVAL;
-	__nested_copy_vmcb_control_to_cache(&ctl_cached, ctl);
+	__nested_copy_vmcb_control_to_cache(vcpu, &ctl_cached, ctl);
 	if (!__nested_vmcb_check_controls(vcpu, &ctl_cached))
 		goto out_free;
 
@@ -1495,6 +1525,7 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
 	if (WARN_ON_ONCE(ret))
 		goto out_free;
 
+	svm->nested.force_msr_bitmap_recalc = true;
 
 	kvm_make_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu);
 	ret = 0;