[PATCH 5/5] KVM: nVMX: Skip Guest State Area vmentry checks that are necessary only if VMCS12 is dirty

[Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>]

  ..so that every nested vmentry is not slowed down by those checks.

Signed-off-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
---
 arch/x86/kvm/vmx/nested.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b610f389a01b..095923b1d765 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2748,10 +2748,23 @@ static int nested_check_guest_non_reg_state(struct vmcs12 *vmcs12)
 	return 0;
 }
 
+static int nested_vmx_check_guest_state_full(struct kvm_vcpu *vcpu,
+					     struct vmcs12 *vmcs12,
+					     u32 *exit_qual)
+{
+	if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS) &&
+	    (is_noncanonical_address(vmcs12->guest_bndcfgs & PAGE_MASK, vcpu) ||
+	     (vmcs12->guest_bndcfgs & MSR_IA32_BNDCFGS_RSVD)))
+		return -EINVAL;
+
+	return 0;
+}
+
 static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
 					struct vmcs12 *vmcs12,
 					u32 *exit_qual)
 {
+	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	bool ia32e;
 
 	*exit_qual = ENTRY_FAIL_DEFAULT;
@@ -2788,10 +2801,9 @@ static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
 			return -EINVAL;
 	}
 
-	if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS) &&
-	    (is_noncanonical_address(vmcs12->guest_bndcfgs & PAGE_MASK, vcpu) ||
-	     (vmcs12->guest_bndcfgs & MSR_IA32_BNDCFGS_RSVD)))
-		return -EINVAL;
+	if (vmx->nested.dirty_vmcs12 &&
+	    nested_vmx_check_guest_state_full(vcpu, vmcs12, exit_qual))
+			return -EINVAL;
 
 	if (nested_check_guest_non_reg_state(vmcs12))
 		return -EINVAL;
-- 
2.20.1