Commit baf6ed17 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: SEV: Set RESET GHCB MSR value during sev_es_init_vmcb() 



Set the RESET value for the GHCB "MSR" during sev_es_init_vmcb() instead
of sev_es_vcpu_reset() to allow for dropping sev_es_vcpu_reset() entirely.

Note, the call to sev_init_vmcb() from sev_migrate_from() also kinda sorta
emulates a RESET, but sev_migrate_from() immediately overwrites ghcb_gpa
with the source's current value, so whether or not stuffing the GHCB
version is correct/desirable is moot.

No functional change intended.

Reviewed-by: default avatarNikunj A Dadhania <nikunj@amd.com>
Link: https://lore.kernel.org/r/20250819234833.3080255-7-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 3d4e882e

arch/x86/kvm/svm/sev.c

+11 −13
Original line number Diff line number Diff line
@@ -4480,7 +4480,7 @@ void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm) 
		vcpu->arch.reserved_gpa_bits &= ~(1UL << (best->ebx & 0x3f));

}



static void sev_es_init_vmcb(struct vcpu_svm *svm)

static void sev_es_init_vmcb(struct vcpu_svm *svm, bool init_event)

{

	struct kvm_sev_info *sev = to_kvm_sev_info(svm->vcpu.kvm);

	struct vmcb *vmcb = svm->vmcb01.ptr;
@@ -4541,6 +4541,15 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm) 


	/* Can't intercept XSETBV, HV can't modify XCR0 directly */

	svm_clr_intercept(svm, INTERCEPT_XSETBV);



	/*

	 * Set the GHCB MSR value as per the GHCB specification when emulating

	 * vCPU RESET for an SEV-ES guest.

	 */

	if (!init_event)

		set_ghcb_msr(svm, GHCB_MSR_SEV_INFO((__u64)sev->ghcb_version,

						    GHCB_VERSION_MIN,

						    sev_enc_bit));

}



void sev_init_vmcb(struct vcpu_svm *svm, bool init_event)
@@ -4560,7 +4569,7 @@ void sev_init_vmcb(struct vcpu_svm *svm, bool init_event) 
		sev_snp_init_protected_guest_state(vcpu);



	if (sev_es_guest(vcpu->kvm))

		sev_es_init_vmcb(svm);

		sev_es_init_vmcb(svm, init_event);

}



int sev_vcpu_create(struct kvm_vcpu *vcpu)
@@ -4585,17 +4594,6 @@ int sev_vcpu_create(struct kvm_vcpu *vcpu) 


void sev_es_vcpu_reset(struct vcpu_svm *svm)

{

	struct kvm_vcpu *vcpu = &svm->vcpu;

	struct kvm_sev_info *sev = to_kvm_sev_info(vcpu->kvm);



	/*

	 * Set the GHCB MSR value as per the GHCB specification when emulating

	 * vCPU RESET for an SEV-ES guest.

	 */

	set_ghcb_msr(svm, GHCB_MSR_SEV_INFO((__u64)sev->ghcb_version,

					    GHCB_VERSION_MIN,

					    sev_enc_bit));



	mutex_init(&svm->sev_es.snp_vmsa_mutex);

}