Commit 469debdb authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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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: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent de0286b7

arch/x86/kvm/vmx/nested.c

+8 −0
Original line number Diff line number Diff line
@@ -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);