Commit 9a0bf054 authored by Suravee Suthikulpanit's avatar Suravee Suthikulpanit Committed by Paolo Bonzini
Browse files

svm: Deactivate AVIC when launching guest with nested SVM support 



Since AVIC does not currently work w/ nested virtualization,
deactivate AVIC for the guest if setting CPUID Fn80000001_ECX[SVM]
(i.e. indicate support for SVM, which is needed for nested virtualization).
Also, introduce a new APICV_INHIBIT_REASON_NESTED bit to be used for
this reason.

Suggested-by: default avatarAlexander Graf <graf@amazon.com>
Signed-off-by: default avatarSuravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent f4fdc0a2

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -877,6 +877,7 @@ enum kvm_irqchip_mode { 


#define APICV_INHIBIT_REASON_DISABLE    0

#define APICV_INHIBIT_REASON_HYPERV     1

#define APICV_INHIBIT_REASON_NESTED     2



struct kvm_arch {

	unsigned long n_used_mmu_pages;

arch/x86/kvm/svm.c

+10 −1
Original line number Diff line number Diff line
@@ -5988,6 +5988,14 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu) 
		return;



	guest_cpuid_clear(vcpu, X86_FEATURE_X2APIC);



	/*

	 * Currently, AVIC does not work with nested virtualization.

	 * So, we disable AVIC when cpuid for SVM is set in the L1 guest.

	 */

	if (nested && guest_cpuid_has(vcpu, X86_FEATURE_SVM))

		kvm_request_apicv_update(vcpu->kvm, false,

					 APICV_INHIBIT_REASON_NESTED);

}



#define F feature_bit
@@ -7319,7 +7327,8 @@ static bool svm_apic_init_signal_blocked(struct kvm_vcpu *vcpu) 
static bool svm_check_apicv_inhibit_reasons(ulong bit)

{

	ulong supported = BIT(APICV_INHIBIT_REASON_DISABLE) |

			  BIT(APICV_INHIBIT_REASON_HYPERV);

			  BIT(APICV_INHIBIT_REASON_HYPERV) |

			  BIT(APICV_INHIBIT_REASON_NESTED);



	return supported & BIT(bit);

}

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