diff mbox series

[v10,21/50] KVM: SEV: Add support to handle AP reset MSR protocol

Message ID 20231016132819.1002933-22-michael.roth@amd.com (mailing list archive)
State New
Headers show
Series Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support | expand

Commit Message

Michael Roth Oct. 16, 2023, 1:27 p.m. UTC 
From: Tom Lendacky <thomas.lendacky@amd.com>

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

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
 arch/x86/include/asm/sev-common.h |  2 ++
 arch/x86/kvm/svm/sev.c            | 56 ++++++++++++++++++++++++++-----
 arch/x86/kvm/svm/svm.h            |  1 +
 3 files changed, 51 insertions(+), 8 deletions(-)

Comments

Borislav Petkov Dec. 12, 2023, 5:02 p.m. UTC | #1 
On Mon, Oct 16, 2023 at 08:27:50AM -0500, Michael Roth wrote:
> From: Tom Lendacky <thomas.lendacky@amd.com>
> 
> Add support for AP Reset Hold being invoked using the GHCB MSR protocol,
> available in version 2 of the GHCB specification.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
> ---
>  arch/x86/include/asm/sev-common.h |  2 ++
>  arch/x86/kvm/svm/sev.c            | 56 ++++++++++++++++++++++++++-----
>  arch/x86/kvm/svm/svm.h            |  1 +
>  3 files changed, 51 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
> index 93ec8c12c91d..57ced29264ce 100644
> --- a/arch/x86/include/asm/sev-common.h
> +++ b/arch/x86/include/asm/sev-common.h
> @@ -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)

Align vertically pls.

>  /* GHCB GPA Register */
>  #define GHCB_MSR_REG_GPA_REQ		0x012
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 6ee925d66648..4f895a7201ed 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -65,6 +65,10 @@ module_param_named(debug_swap, sev_es_debug_swap_enabled, bool, 0444);
>  #define sev_es_debug_swap_enabled false
>  #endif /* CONFIG_KVM_AMD_SEV */
>  
> +#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);
> @@ -2594,6 +2598,9 @@ 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;
>  
> @@ -2805,6 +2812,22 @@ 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);

Yikes, those defines are a mouthful.
diff mbox series

Patch

diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index 93ec8c12c91d..57ced29264ce 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -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
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 6ee925d66648..4f895a7201ed 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -65,6 +65,10 @@  module_param_named(debug_swap, sev_es_debug_swap_enabled, bool, 0444);
 #define sev_es_debug_swap_enabled false
 #endif /* CONFIG_KVM_AMD_SEV */
 
+#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);
@@ -2594,6 +2598,9 @@  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;
 
@@ -2805,6 +2812,22 @@  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;
 
@@ -2904,6 +2927,7 @@  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: {
@@ -3147,13 +3171,29 @@  void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector)
 		return;
 	}
 
-	/*
-	 * 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.
-	 */
-	if (!svm->sev_es.ghcb)
-		return;
+	/* Subsequent SIPI */
+	switch (svm->sev_es.ap_reset_hold_type) {
+	case AP_RESET_HOLD_NAE_EVENT:
+		/*
+		 * 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.
+		 */
+		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);
 
-	ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, 1);
+		set_ghcb_msr_bits(svm, GHCB_MSR_AP_RESET_HOLD_RESP,
+				  GHCB_MSR_INFO_MASK,
+				  GHCB_MSR_INFO_POS);
+		break;
+	default:
+		break;
+	}
 }
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index c409f934c377..b74231511493 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -195,6 +195,7 @@  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;