Commit 4b639a9f authored by Maxim Levitsky's avatar Maxim Levitsky Committed by Paolo Bonzini
Browse files

KVM: SVM: add module param to control the #SMI interception 



In theory there are no side effects of not intercepting #SMI,
because then #SMI becomes transparent to the OS and the KVM.

Plus an observation on recent Zen2 CPUs reveals that these
CPUs ignore #SMI interception and never deliver #SMI VMexits.

This is also useful to test nested KVM to see that L1
handles #SMIs correctly in case when L1 doesn't intercept #SMI.

Finally the default remains the same, the SMI are intercepted
by default thus this patch doesn't have any effect unless
non default module param value is used.

Signed-off-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210707125100.677203-4-mlevitsk@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 896707c2

arch/x86/kvm/svm/nested.c

+4 −0
Original line number Diff line number Diff line
@@ -154,6 +154,10 @@ void recalc_intercepts(struct vcpu_svm *svm) 


	for (i = 0; i < MAX_INTERCEPT; i++)

		c->intercepts[i] |= g->intercepts[i];



	/* If SMI is not intercepted, ignore guest SMI intercept as well  */

	if (!intercept_smi)

		vmcb_clr_intercept(c, INTERCEPT_SMI);

}



static void copy_vmcb_control_area(struct vmcb_control_area *dst,

arch/x86/kvm/svm/svm.c

+9 −1
Original line number Diff line number Diff line
@@ -198,6 +198,11 @@ module_param(avic, bool, 0444); 
bool __read_mostly dump_invalid_vmcb;

module_param(dump_invalid_vmcb, bool, 0644);





bool intercept_smi = true;

module_param(intercept_smi, bool, 0444);





static bool svm_gp_erratum_intercept = true;



static u8 rsm_ins_bytes[] = "\x0f\xaa";
@@ -1185,7 +1190,10 @@ static void init_vmcb(struct kvm_vcpu *vcpu) 


	svm_set_intercept(svm, INTERCEPT_INTR);

	svm_set_intercept(svm, INTERCEPT_NMI);



	if (intercept_smi)

		svm_set_intercept(svm, INTERCEPT_SMI);



	svm_set_intercept(svm, INTERCEPT_SELECTIVE_CR0);

	svm_set_intercept(svm, INTERCEPT_RDPMC);

	svm_set_intercept(svm, INTERCEPT_CPUID);

arch/x86/kvm/svm/svm.h

+1 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#define MSRPM_OFFSETS	16

extern u32 msrpm_offsets[MSRPM_OFFSETS] __read_mostly;

extern bool npt_enabled;

extern bool intercept_smi;



/*

 * Clean bits in VMCB.