Commit 0c76b1d0 authored by Brijesh Singh's avatar Brijesh Singh Committed by Paolo Bonzini
Browse files

KVM: SEV: Add support to handle GHCB GPA register VMGEXIT 



SEV-SNP guests are required to perform a GHCB GPA registration. Before
using a GHCB GPA for a vCPU the first time, a guest must register the
vCPU GHCB GPA. If hypervisor can work with the guest requested GPA then
it must respond back with the same GPA otherwise return -1.

On VMEXIT, verify that the GHCB GPA matches with the registered value.
If a mismatch is detected, then abort the guest.

Signed-off-by: default avatarBrijesh Singh <brijesh.singh@amd.com>
Signed-off-by: default avatarAshish Kalra <ashish.kalra@amd.com>
Signed-off-by: default avatarMichael Roth <michael.roth@amd.com>
Message-ID: <20240501085210.2213060-9-michael.roth@amd.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent ad27ce15

arch/x86/include/asm/sev-common.h

+8 −0
Original line number Diff line number Diff line
@@ -59,6 +59,14 @@ 
#define GHCB_MSR_AP_RESET_HOLD_RESULT_POS	12

#define GHCB_MSR_AP_RESET_HOLD_RESULT_MASK	GENMASK_ULL(51, 0)



/* Preferred GHCB GPA Request */

#define GHCB_MSR_PREF_GPA_REQ		0x010

#define GHCB_MSR_GPA_VALUE_POS		12

#define GHCB_MSR_GPA_VALUE_MASK		GENMASK_ULL(51, 0)



#define GHCB_MSR_PREF_GPA_RESP		0x011

#define GHCB_MSR_PREF_GPA_NONE		0xfffffffffffff



/* GHCB GPA Register */

#define GHCB_MSR_REG_GPA_REQ		0x012

#define GHCB_MSR_REG_GPA_REQ_VAL(v)			\

arch/x86/kvm/svm/sev.c

+42 −6
Original line number Diff line number Diff line
@@ -3540,6 +3540,32 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm) 
		set_ghcb_msr_bits(svm, GHCB_MSR_HV_FT_RESP,

				  GHCB_MSR_INFO_MASK, GHCB_MSR_INFO_POS);

		break;

	case GHCB_MSR_PREF_GPA_REQ:

		if (!sev_snp_guest(vcpu->kvm))

			goto out_terminate;



		set_ghcb_msr_bits(svm, GHCB_MSR_PREF_GPA_NONE, GHCB_MSR_GPA_VALUE_MASK,

				  GHCB_MSR_GPA_VALUE_POS);

		set_ghcb_msr_bits(svm, GHCB_MSR_PREF_GPA_RESP, GHCB_MSR_INFO_MASK,

				  GHCB_MSR_INFO_POS);

		break;

	case GHCB_MSR_REG_GPA_REQ: {

		u64 gfn;



		if (!sev_snp_guest(vcpu->kvm))

			goto out_terminate;



		gfn = get_ghcb_msr_bits(svm, GHCB_MSR_GPA_VALUE_MASK,

					GHCB_MSR_GPA_VALUE_POS);



		svm->sev_es.ghcb_registered_gpa = gfn_to_gpa(gfn);



		set_ghcb_msr_bits(svm, gfn, GHCB_MSR_GPA_VALUE_MASK,

				  GHCB_MSR_GPA_VALUE_POS);

		set_ghcb_msr_bits(svm, GHCB_MSR_REG_GPA_RESP, GHCB_MSR_INFO_MASK,

				  GHCB_MSR_INFO_POS);

		break;

	}

	case GHCB_MSR_TERM_REQ: {

		u64 reason_set, reason_code;
@@ -3552,12 +3578,7 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm) 
		pr_info("SEV-ES guest requested termination: %#llx:%#llx\n",

			reason_set, reason_code);



		vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;

		vcpu->run->system_event.type = KVM_SYSTEM_EVENT_SEV_TERM;

		vcpu->run->system_event.ndata = 1;

		vcpu->run->system_event.data[0] = control->ghcb_gpa;



		return 0;

		goto out_terminate;

	}

	default:

		/* Error, keep GHCB MSR value as-is */
@@ -3568,6 +3589,14 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm) 
					    control->ghcb_gpa, ret);



	return ret;



out_terminate:

	vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;

	vcpu->run->system_event.type = KVM_SYSTEM_EVENT_SEV_TERM;

	vcpu->run->system_event.ndata = 1;

	vcpu->run->system_event.data[0] = control->ghcb_gpa;



	return 0;

}



int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
@@ -3603,6 +3632,13 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) 
	trace_kvm_vmgexit_enter(vcpu->vcpu_id, svm->sev_es.ghcb);



	sev_es_sync_from_ghcb(svm);



	/* SEV-SNP guest requires that the GHCB GPA must be registered */

	if (sev_snp_guest(svm->vcpu.kvm) && !ghcb_gpa_is_registered(svm, ghcb_gpa)) {

		vcpu_unimpl(&svm->vcpu, "vmgexit: GHCB GPA [%#llx] is not registered.\n", ghcb_gpa);

		return -EINVAL;

	}



	ret = sev_es_validate_vmgexit(svm);

	if (ret)

		return ret;

arch/x86/kvm/svm/svm.h

+7 −0
Original line number Diff line number Diff line
@@ -209,6 +209,8 @@ struct vcpu_sev_es_state { 
	u32 ghcb_sa_len;

	bool ghcb_sa_sync;

	bool ghcb_sa_free;



	u64 ghcb_registered_gpa;

};



struct vcpu_svm {
@@ -362,6 +364,11 @@ static __always_inline bool sev_snp_guest(struct kvm *kvm) 
#endif

}



static inline bool ghcb_gpa_is_registered(struct vcpu_svm *svm, u64 val)

{

	return svm->sev_es.ghcb_registered_gpa == val;

}



static inline void vmcb_mark_all_dirty(struct vmcb *vmcb)

{

	vmcb->control.clean = 0;