diff mbox series

[05/10] KVM: SEV: store VMSA features in kvm_sev_info

Message ID 20240209183743.22030-6-pbonzini@redhat.com (mailing list archive)
State New, archived
Headers show
Series KVM: SEV: allow customizing VMSA features | expand

Commit Message

Paolo Bonzini Feb. 9, 2024, 6:37 p.m. UTC 
Right now, the set of features that are stored in the VMSA upon
initialization is fixed and depends on the module parameters for
kvm-amd.ko.  However, the hypervisor cannot really change it at will
because the feature word has to match between the hypervisor and whatever
computes a measurement of the VMSA for attestation purposes.

Add a field to kvm_set_info that holds the set of features to be stored
in the VMSA; and query it instead of referring to the module parameters.

Because KVM_SEV_INIT and KVM_SEV_ES_INIT accept no parameters, this
does not yet introduce any functional change, but it paves the way for
an API that allows customization of the features per-VM.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/svm/sev.c | 22 ++++++++++++++++++----
 arch/x86/kvm/svm/svm.c |  2 +-
 arch/x86/kvm/svm/svm.h |  3 ++-
 3 files changed, 21 insertions(+), 6 deletions(-)

Comments

Michael Roth Feb. 15, 2024, 12:03 a.m. UTC | #1 
On Fri, Feb 09, 2024 at 01:37:37PM -0500, Paolo Bonzini wrote:
> Right now, the set of features that are stored in the VMSA upon
> initialization is fixed and depends on the module parameters for
> kvm-amd.ko.  However, the hypervisor cannot really change it at will
> because the feature word has to match between the hypervisor and whatever
> computes a measurement of the VMSA for attestation purposes.
> 
> Add a field to kvm_set_info that holds the set of features to be stored

s/kvm_set_info_/kvm_sev_info/

Otherwise:

Reviewed-by: Michael Roth <michael.roth@amd.com>

> in the VMSA; and query it instead of referring to the module parameters.
> 
> Because KVM_SEV_INIT and KVM_SEV_ES_INIT accept no parameters, this
> does not yet introduce any functional change, but it paves the way for
> an API that allows customization of the features per-VM.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  arch/x86/kvm/svm/sev.c | 22 ++++++++++++++++++----
>  arch/x86/kvm/svm/svm.c |  2 +-
>  arch/x86/kvm/svm/svm.h |  3 ++-
>  3 files changed, 21 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 2e558f7538c2..712bfbc0028a 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -116,6 +116,14 @@ static inline bool is_mirroring_enc_context(struct kvm *kvm)
>  	return !!to_kvm_svm(kvm)->sev_info.enc_context_owner;
>  }
> 
> +static bool sev_vcpu_has_debug_swap(struct vcpu_svm *svm)
> +{
> +	struct kvm_vcpu *vcpu = &svm->vcpu;
> +	struct kvm_sev_info *sev = &to_kvm_svm(vcpu->kvm)->sev_info;
> +
> +	return sev->vmsa_features & SVM_SEV_FEAT_DEBUG_SWAP;
> +}
> +
>  /* Must be called with the sev_bitmap_lock held */
>  static bool __sev_recycle_asids(int min_asid, int max_asid)
>  {
> @@ -258,6 +266,8 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
> 
>  	sev->active = true;
>  	sev->es_active = argp->id == KVM_SEV_ES_INIT;
> +	sev->vmsa_features = sev_supported_vmsa_features;
> +
>  	asid = sev_asid_new(sev);
>  	if (asid < 0)
>  		goto e_no_asid;
> @@ -278,6 +288,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
>  	sev_asid_free(sev);
>  	sev->asid = 0;
>  e_no_asid:
> +	sev->vmsa_features = 0;
>  	sev->es_active = false;
>  	sev->active = false;
>  	return ret;
> @@ -572,6 +583,8 @@ static int sev_launch_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
> 
>  static int sev_es_sync_vmsa(struct vcpu_svm *svm)
>  {
> +	struct kvm_vcpu *vcpu = &svm->vcpu;
> +	struct kvm_sev_info *sev = &to_kvm_svm(vcpu->kvm)->sev_info;
>  	struct sev_es_save_area *save = svm->sev_es.vmsa;
> 
>  	/* Check some debug related fields before encrypting the VMSA */
> @@ -613,7 +626,7 @@ static int sev_es_sync_vmsa(struct vcpu_svm *svm)
>  	save->xss  = svm->vcpu.arch.ia32_xss;
>  	save->dr6  = svm->vcpu.arch.dr6;
> 
> -	save->sev_features = sev_supported_vmsa_features;
> +	save->sev_features = sev->vmsa_features;
> 
>  	pr_debug("Virtual Machine Save Area (VMSA):\n");
>  	print_hex_dump_debug("", DUMP_PREFIX_NONE, 16, 1, save, sizeof(*save), false);
> @@ -1693,6 +1706,7 @@ static void sev_migrate_from(struct kvm *dst_kvm, struct kvm *src_kvm)
>  	dst->pages_locked = src->pages_locked;
>  	dst->enc_context_owner = src->enc_context_owner;
>  	dst->es_active = src->es_active;
> +	dst->vmsa_features = src->vmsa_features;
> 
>  	src->asid = 0;
>  	src->active = false;
> @@ -3063,7 +3077,7 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm)
>  	svm_set_intercept(svm, TRAP_CR8_WRITE);
> 
>  	vmcb->control.intercepts[INTERCEPT_DR] = 0;
> -	if (!sev_es_debug_swap_enabled) {
> +	if (!sev_vcpu_has_debug_swap(svm)) {
>  		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_READ);
>  		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_WRITE);
>  		recalc_intercepts(svm);
> @@ -3118,7 +3132,7 @@ void sev_es_vcpu_reset(struct vcpu_svm *svm)
>  					    sev_enc_bit));
>  }
> 
> -void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa)
> +void sev_es_prepare_switch_to_guest(struct vcpu_svm *svm, struct sev_es_save_area *hostsa)
>  {
>  	/*
>  	 * All host state for SEV-ES guests is categorized into three swap types
> @@ -3146,7 +3160,7 @@ void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa)
>  	 * the CPU (Type-B). If DebugSwap is disabled/unsupported, the CPU both
>  	 * saves and loads debug registers (Type-A).
>  	 */
> -	if (sev_es_debug_swap_enabled) {
> +	if (sev_vcpu_has_debug_swap(svm)) {
>  		hostsa->dr0 = native_get_debugreg(0);
>  		hostsa->dr1 = native_get_debugreg(1);
>  		hostsa->dr2 = native_get_debugreg(2);
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index aa1792f402ab..392b9c2e2ce1 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -1523,7 +1523,7 @@ static void svm_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
>  		struct sev_es_save_area *hostsa;
>  		hostsa = (struct sev_es_save_area *)(page_address(sd->save_area) + 0x400);
> 
> -		sev_es_prepare_switch_to_guest(hostsa);
> +		sev_es_prepare_switch_to_guest(svm, hostsa);
>  	}
> 
>  	if (tsc_scaling)
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index d630026b23b0..864c782eaa58 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -85,6 +85,7 @@ struct kvm_sev_info {
>  	unsigned long pages_locked; /* Number of pages locked */
>  	struct list_head regions_list;  /* List of registered regions */
>  	u64 ap_jump_table;	/* SEV-ES AP Jump Table address */
> +	u64 vmsa_features;
>  	struct kvm *enc_context_owner; /* Owner of copied encryption context */
>  	struct list_head mirror_vms; /* List of VMs mirroring */
>  	struct list_head mirror_entry; /* Use as a list entry of mirrors */
> @@ -693,7 +694,7 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu);
>  int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in);
>  void sev_es_vcpu_reset(struct vcpu_svm *svm);
>  void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector);
> -void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa);
> +void sev_es_prepare_switch_to_guest(struct vcpu_svm *svm, struct sev_es_save_area *hostsa);
>  void sev_es_unmap_ghcb(struct vcpu_svm *svm);
> 
>  /* vmenter.S */
> -- 
> 2.39.0
> 
> 
>
diff mbox series

Patch

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 2e558f7538c2..712bfbc0028a 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -116,6 +116,14 @@  static inline bool is_mirroring_enc_context(struct kvm *kvm)
 	return !!to_kvm_svm(kvm)->sev_info.enc_context_owner;
 }
 
+static bool sev_vcpu_has_debug_swap(struct vcpu_svm *svm)
+{
+	struct kvm_vcpu *vcpu = &svm->vcpu;
+	struct kvm_sev_info *sev = &to_kvm_svm(vcpu->kvm)->sev_info;
+
+	return sev->vmsa_features & SVM_SEV_FEAT_DEBUG_SWAP;
+}
+
 /* Must be called with the sev_bitmap_lock held */
 static bool __sev_recycle_asids(int min_asid, int max_asid)
 {
@@ -258,6 +266,8 @@  static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 
 	sev->active = true;
 	sev->es_active = argp->id == KVM_SEV_ES_INIT;
+	sev->vmsa_features = sev_supported_vmsa_features;
+
 	asid = sev_asid_new(sev);
 	if (asid < 0)
 		goto e_no_asid;
@@ -278,6 +288,7 @@  static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	sev_asid_free(sev);
 	sev->asid = 0;
 e_no_asid:
+	sev->vmsa_features = 0;
 	sev->es_active = false;
 	sev->active = false;
 	return ret;
@@ -572,6 +583,8 @@  static int sev_launch_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
 
 static int sev_es_sync_vmsa(struct vcpu_svm *svm)
 {
+	struct kvm_vcpu *vcpu = &svm->vcpu;
+	struct kvm_sev_info *sev = &to_kvm_svm(vcpu->kvm)->sev_info;
 	struct sev_es_save_area *save = svm->sev_es.vmsa;
 
 	/* Check some debug related fields before encrypting the VMSA */
@@ -613,7 +626,7 @@  static int sev_es_sync_vmsa(struct vcpu_svm *svm)
 	save->xss  = svm->vcpu.arch.ia32_xss;
 	save->dr6  = svm->vcpu.arch.dr6;
 
-	save->sev_features = sev_supported_vmsa_features;
+	save->sev_features = sev->vmsa_features;
 
 	pr_debug("Virtual Machine Save Area (VMSA):\n");
 	print_hex_dump_debug("", DUMP_PREFIX_NONE, 16, 1, save, sizeof(*save), false);
@@ -1693,6 +1706,7 @@  static void sev_migrate_from(struct kvm *dst_kvm, struct kvm *src_kvm)
 	dst->pages_locked = src->pages_locked;
 	dst->enc_context_owner = src->enc_context_owner;
 	dst->es_active = src->es_active;
+	dst->vmsa_features = src->vmsa_features;
 
 	src->asid = 0;
 	src->active = false;
@@ -3063,7 +3077,7 @@  static void sev_es_init_vmcb(struct vcpu_svm *svm)
 	svm_set_intercept(svm, TRAP_CR8_WRITE);
 
 	vmcb->control.intercepts[INTERCEPT_DR] = 0;
-	if (!sev_es_debug_swap_enabled) {
+	if (!sev_vcpu_has_debug_swap(svm)) {
 		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_READ);
 		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_WRITE);
 		recalc_intercepts(svm);
@@ -3118,7 +3132,7 @@  void sev_es_vcpu_reset(struct vcpu_svm *svm)
 					    sev_enc_bit));
 }
 
-void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa)
+void sev_es_prepare_switch_to_guest(struct vcpu_svm *svm, struct sev_es_save_area *hostsa)
 {
 	/*
 	 * All host state for SEV-ES guests is categorized into three swap types
@@ -3146,7 +3160,7 @@  void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa)
 	 * the CPU (Type-B). If DebugSwap is disabled/unsupported, the CPU both
 	 * saves and loads debug registers (Type-A).
 	 */
-	if (sev_es_debug_swap_enabled) {
+	if (sev_vcpu_has_debug_swap(svm)) {
 		hostsa->dr0 = native_get_debugreg(0);
 		hostsa->dr1 = native_get_debugreg(1);
 		hostsa->dr2 = native_get_debugreg(2);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index aa1792f402ab..392b9c2e2ce1 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1523,7 +1523,7 @@  static void svm_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
 		struct sev_es_save_area *hostsa;
 		hostsa = (struct sev_es_save_area *)(page_address(sd->save_area) + 0x400);
 
-		sev_es_prepare_switch_to_guest(hostsa);
+		sev_es_prepare_switch_to_guest(svm, hostsa);
 	}
 
 	if (tsc_scaling)
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index d630026b23b0..864c782eaa58 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -85,6 +85,7 @@  struct kvm_sev_info {
 	unsigned long pages_locked; /* Number of pages locked */
 	struct list_head regions_list;  /* List of registered regions */
 	u64 ap_jump_table;	/* SEV-ES AP Jump Table address */
+	u64 vmsa_features;
 	struct kvm *enc_context_owner; /* Owner of copied encryption context */
 	struct list_head mirror_vms; /* List of VMs mirroring */
 	struct list_head mirror_entry; /* Use as a list entry of mirrors */
@@ -693,7 +694,7 @@  int sev_handle_vmgexit(struct kvm_vcpu *vcpu);
 int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in);
 void sev_es_vcpu_reset(struct vcpu_svm *svm);
 void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector);
-void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa);
+void sev_es_prepare_switch_to_guest(struct vcpu_svm *svm, struct sev_es_save_area *hostsa);
 void sev_es_unmap_ghcb(struct vcpu_svm *svm);
 
 /* vmenter.S */