Commit d916f003 authored by Tom Lendacky's avatar Tom Lendacky Committed by Paolo Bonzini
Browse files

KVM: SEV: Add support to handle AP reset MSR protocol 



Add support for AP Reset Hold being invoked using the GHCB MSR protocol,
available in version 2 of the GHCB specification.

Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
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: <20240501071048.2208265-2-michael.roth@amd.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent a96cb3bf

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

+4 −2
Original line number Diff line number Diff line
@@ -56,6 +56,8 @@ 
/* AP Reset Hold */

#define GHCB_MSR_AP_RESET_HOLD_REQ		0x006

#define GHCB_MSR_AP_RESET_HOLD_RESP		0x007

#define GHCB_MSR_AP_RESET_HOLD_RESULT_POS	12

#define GHCB_MSR_AP_RESET_HOLD_RESULT_MASK	GENMASK_ULL(51, 0)



/* GHCB GPA Register */

#define GHCB_MSR_REG_GPA_REQ		0x012

arch/x86/kvm/svm/sev.c

+48 −8
Original line number Diff line number Diff line
@@ -49,6 +49,10 @@ static bool sev_es_debug_swap_enabled = true; 
module_param_named(debug_swap, sev_es_debug_swap_enabled, bool, 0444);

static u64 sev_supported_vmsa_features;



#define AP_RESET_HOLD_NONE		0

#define AP_RESET_HOLD_NAE_EVENT		1

#define AP_RESET_HOLD_MSR_PROTO		2



static u8 sev_enc_bit;

static DECLARE_RWSEM(sev_deactivate_lock);

static DEFINE_MUTEX(sev_bitmap_lock);
@@ -2727,6 +2731,9 @@ static int sev_es_validate_vmgexit(struct vcpu_svm *svm) 


void sev_es_unmap_ghcb(struct vcpu_svm *svm)

{

	/* Clear any indication that the vCPU is in a type of AP Reset Hold */

	svm->sev_es.ap_reset_hold_type = AP_RESET_HOLD_NONE;



	if (!svm->sev_es.ghcb)

		return;
@@ -2938,6 +2945,22 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm) 
				  GHCB_MSR_INFO_POS);

		break;

	}

	case GHCB_MSR_AP_RESET_HOLD_REQ:

		svm->sev_es.ap_reset_hold_type = AP_RESET_HOLD_MSR_PROTO;

		ret = kvm_emulate_ap_reset_hold(&svm->vcpu);



		/*

		 * Preset the result to a non-SIPI return and then only set

		 * the result to non-zero when delivering a SIPI.

		 */

		set_ghcb_msr_bits(svm, 0,

				  GHCB_MSR_AP_RESET_HOLD_RESULT_MASK,

				  GHCB_MSR_AP_RESET_HOLD_RESULT_POS);



		set_ghcb_msr_bits(svm, GHCB_MSR_AP_RESET_HOLD_RESP,

				  GHCB_MSR_INFO_MASK,

				  GHCB_MSR_INFO_POS);

		break;

	case GHCB_MSR_TERM_REQ: {

		u64 reason_set, reason_code;
@@ -3037,6 +3060,7 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) 
		ret = 1;

		break;

	case SVM_VMGEXIT_AP_HLT_LOOP:

		svm->sev_es.ap_reset_hold_type = AP_RESET_HOLD_NAE_EVENT;

		ret = kvm_emulate_ap_reset_hold(vcpu);

		break;

	case SVM_VMGEXIT_AP_JUMP_TABLE: {
@@ -3280,15 +3304,31 @@ void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector) 
		return;

	}



	/* Subsequent SIPI */

	switch (svm->sev_es.ap_reset_hold_type) {

	case AP_RESET_HOLD_NAE_EVENT:

		/*

	 * Subsequent SIPI: Return from an AP Reset Hold VMGEXIT, where

	 * the guest will set the CS and RIP. Set SW_EXIT_INFO_2 to a

	 * non-zero value.

		 * Return from an AP Reset Hold VMGEXIT, where the guest will

		 * set the CS and RIP. Set SW_EXIT_INFO_2 to a non-zero value.

		 */

	if (!svm->sev_es.ghcb)

		return;



		ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, 1);

		break;

	case AP_RESET_HOLD_MSR_PROTO:

		/*

		 * Return from an AP Reset Hold VMGEXIT, where the guest will

		 * set the CS and RIP. Set GHCB data field to a non-zero value.

		 */

		set_ghcb_msr_bits(svm, 1,

				  GHCB_MSR_AP_RESET_HOLD_RESULT_MASK,

				  GHCB_MSR_AP_RESET_HOLD_RESULT_POS);



		set_ghcb_msr_bits(svm, GHCB_MSR_AP_RESET_HOLD_RESP,

				  GHCB_MSR_INFO_MASK,

				  GHCB_MSR_INFO_POS);

		break;

	default:

		break;

	}

}



struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu)

arch/x86/kvm/svm/svm.h

+1 −0
Original line number Diff line number Diff line
@@ -199,6 +199,7 @@ struct vcpu_sev_es_state { 
	u8 valid_bitmap[16];

	struct kvm_host_map ghcb_map;

	bool received_first_sipi;

	unsigned int ap_reset_hold_type;



	/* SEV-ES scratch area support */

	u64 sw_scratch;