Commit 656ec4a4 authored by Radim Krčmář's avatar Radim Krčmář Committed by Paolo Bonzini
Browse files

KVM: VMX: fix SMEP and SMAP without EPT 



The comment in code had it mostly right, but we enable paging for
emulated real mode regardless of EPT.

Without EPT (which implies emulated real mode), secondary VCPUs won't
start unless we disable SM[AE]P when the guest doesn't use paging.

Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 8a22f234

arch/x86/kvm/vmx.c

+10 −9
Original line number Diff line number Diff line
@@ -3788,20 +3788,21 @@ static int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) 
		if (!is_paging(vcpu)) {

			hw_cr4 &= ~X86_CR4_PAE;

			hw_cr4 |= X86_CR4_PSE;

			/*

			 * SMEP/SMAP is disabled if CPU is in non-paging mode

			 * in hardware. However KVM always uses paging mode to

			 * emulate guest non-paging mode with TDP.

			 * To emulate this behavior, SMEP/SMAP needs to be

			 * manually disabled when guest switches to non-paging

			 * mode.

			 */

			hw_cr4 &= ~(X86_CR4_SMEP | X86_CR4_SMAP);

		} else if (!(cr4 & X86_CR4_PAE)) {

			hw_cr4 &= ~X86_CR4_PAE;

		}

	}



	if (!enable_unrestricted_guest && !is_paging(vcpu))

		/*

		 * SMEP/SMAP is disabled if CPU is in non-paging mode in

		 * hardware.  However KVM always uses paging mode without

		 * unrestricted guest.

		 * To emulate this behavior, SMEP/SMAP needs to be manually

		 * disabled when guest switches to non-paging mode.

		 */

		hw_cr4 &= ~(X86_CR4_SMEP | X86_CR4_SMAP);



	vmcs_writel(CR4_READ_SHADOW, cr4);

	vmcs_writel(GUEST_CR4, hw_cr4);

	return 0;

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