Commit 605bbdc1 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: SEV: store VMSA features in kvm_sev_info 



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_sev_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: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20240209183743.22030-6-pbonzini@redhat.com>
Reviewed-by: default avatarMichael Roth <michael.roth@amd.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-ID: <20240404121327.3107131-7-pbonzini@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent ac5c4802

arch/x86/kvm/svm/sev.c

+21 −8
Original line number Diff line number Diff line
@@ -99,6 +99,14 @@ 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(unsigned int min_asid, unsigned int max_asid)

{
@@ -248,6 +256,11 @@ 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;

	if (sev_supported_vmsa_features)

		pr_warn_once("Enabling DebugSwap with KVM_SEV_ES_INIT. "

			     "This will not work starting with Linux 6.10\n");



	ret = sev_asid_new(sev);

	if (ret)

		goto e_no_asid;
@@ -269,6 +282,7 @@ 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;
@@ -563,6 +577,8 @@ 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 */
@@ -604,11 +620,7 @@ static int sev_es_sync_vmsa(struct vcpu_svm *svm) 
	save->xss  = svm->vcpu.arch.ia32_xss;

	save->dr6  = svm->vcpu.arch.dr6;



	if (sev_supported_vmsa_features) {

		save->sev_features = sev_supported_vmsa_features;

		pr_warn_once("Enabling DebugSwap with KVM_SEV_ES_INIT. "

			     "This will not work starting with Linux 6.10\n");

	}

	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);
@@ -1688,6 +1700,7 @@ 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 +3076,7 @@ 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 +3131,7 @@ 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 +3159,7 @@ 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);

arch/x86/kvm/svm/svm.c

+1 −1
Original line number Diff line number Diff line
@@ -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)

arch/x86/kvm/svm/svm.h

+2 −1
Original line number Diff line number Diff line
@@ -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 */
@@ -670,7 +671,7 @@ void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm); 
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);



#ifdef CONFIG_KVM_AMD_SEV