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authorSean Christopherson <sean.j.christopherson@intel.com>2019-05-07 12:18:02 -0700
committerPaolo Bonzini <pbonzini@redhat.com>2019-06-18 11:47:45 +0200
commit469debdb8be5814c71c146ce8e21ae7363ae644d (patch)
tree698d1aa91975b05748862bc8f12342575d04af1b /arch/x86/kvm
parentde0286b7884a6a3309e299dda876810faa281547 (diff)
KVM: nVMX: Preset *DT exiting in vmcs02 when emulating UMIP
KVM dynamically toggles SECONDARY_EXEC_DESC to intercept (a subset of) instructions that are subject to User-Mode Instruction Prevention, i.e. VMCS.SECONDARY_EXEC_DESC == CR4.UMIP when emulating UMIP. Preset the VMCS control when preparing vmcs02 to avoid unnecessarily VMWRITEs, e.g. KVM will clear VMCS.SECONDARY_EXEC_DESC in prepare_vmcs02_early() and then set it in vmx_set_cr4(). Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
-rw-r--r--arch/x86/kvm/vmx/nested.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 54b7726c5bf5..23c310adea7d 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2085,6 +2085,14 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
/* VMCS shadowing for L2 is emulated for now */
exec_control &= ~SECONDARY_EXEC_SHADOW_VMCS;
+ /*
+ * Preset *DT exiting when emulating UMIP, so that vmx_set_cr4()
+ * will not have to rewrite the controls just for this bit.
+ */
+ if (!boot_cpu_has(X86_FEATURE_UMIP) && vmx_umip_emulated() &&
+ (vmcs12->guest_cr4 & X86_CR4_UMIP))
+ exec_control |= SECONDARY_EXEC_DESC;
+
if (exec_control & SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY)
vmcs_write16(GUEST_INTR_STATUS,
vmcs12->guest_intr_status);