diff mbox series

[V11,3/5] KVM: SEV: Add support for SEV-ES intra host migration

Message ID 20211021174303.385706-4-pgonda@google.com (mailing list archive)
State New, archived
Headers show
Series Add AMD SEV and SEV-ES intra host migration support | expand

Commit Message

Peter Gonda Oct. 21, 2021, 5:43 p.m. UTC 
For SEV-ES to work with intra host migration the VMSAs, GHCB metadata,
and other SEV-ES info needs to be preserved along with the guest's
memory.

Signed-off-by: Peter Gonda <pgonda@google.com>
Reviewed-by: Marc Orr <marcorr@google.com>
Cc: Marc Orr <marcorr@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 arch/x86/kvm/svm/sev.c | 50 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

Comments

Sean Christopherson Nov. 4, 2021, 11:33 p.m. UTC | #1 
On Thu, Oct 21, 2021, Peter Gonda wrote:
> ---
>  arch/x86/kvm/svm/sev.c | 50 +++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 49 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 2c2f724c9096..d8ce93fd1129 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -1605,6 +1605,48 @@ static void sev_migrate_from(struct kvm_sev_info *dst,
>  	list_replace_init(&src->regions_list, &dst->regions_list);
>  }
>  
> +static int sev_es_migrate_from(struct kvm *dst, struct kvm *src)
> +{
> +	int i;
> +	struct kvm_vcpu *dst_vcpu, *src_vcpu;
> +	struct vcpu_svm *dst_svm, *src_svm;

What do you think about following the style of svm_vm_migrate_from(), where the
"dst" is simply "kvm"?  I like that because (a) it shortens all of these lines,
and (b) conveys the idea that the functions are running in the context of "this"
kvm, as opposed to being a third party that operates on an unrelated source and
destination.

> +
> +	if (atomic_read(&src->online_vcpus) != atomic_read(&dst->online_vcpus))
> +		return -EINVAL;
> +
> +	kvm_for_each_vcpu(i, src_vcpu, src) {
> +		if (!src_vcpu->arch.guest_state_protected)
> +			return -EINVAL;
> +	}
> +
> +	kvm_for_each_vcpu(i, src_vcpu, src) {
> +		src_svm = to_svm(src_vcpu);
> +		dst_vcpu = kvm_get_vcpu(dst, i);
> +		dst_svm = to_svm(dst_vcpu);
> +
> +		/*
> +		 * Transfer VMSA and GHCB state to the destination.  Nullify and
> +		 * clear source fields as appropriate, the state now belongs to
> +		 * the destination.
> +		 */
> +		dst_vcpu->vcpu_id = src_vcpu->vcpu_id;

vcpu_id is an odd thing to copy over.  That's fully controlled by userspace, and
is effectively immutable in KVM.  I don't think SEV-ES should be touching anything
besides SEV-ES state.

> +		dst_svm->sev_es = src_svm->sev_es;

Uber nit, maybe use memcpy() to "pair" with the memset() below?

> +		dst_svm->vmcb->control.ghcb_gpa =
> +			src_svm->vmcb->control.ghcb_gpa;
> +		dst_svm->vmcb->control.vmsa_pa = __pa(dst_svm->sev_es.vmsa);

Oof!  This _looks_ wrong, but it's not because dst_svm->sev_es.vmsa is copied
from the source in that subtle not-memcpy()-memcpy above.  The result of __pa()
absolutely will not change, so I would say just do the obvious

		dst_svm->vmcb->control.vmsa_pa = src_svm->vmcb->control.vmsa_pa;

and not force readers to think too hard.  That also avoids breakage if the order
is changed.

> +		dst_vcpu->arch.guest_state_protected = true;
> +
> +		memset(&src_svm->sev_es, 0, sizeof(src_svm->sev_es));
> +		src_svm->vmcb->control.ghcb_gpa = 0;
> +		src_svm->vmcb->control.vmsa_pa = 0;

'0' is not an invalid (G)PA.  INVALID_PAGE would be the most appropriate.

> +		src_vcpu->arch.guest_state_protected = false;
> +	}
> +	to_kvm_svm(src)->sev_info.es_active = false;
> +	to_kvm_svm(dst)->sev_info.es_active = true;
> +
> +	return 0;
> +}
> +
>  int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
>  {
>  	struct kvm_sev_info *dst_sev = &to_kvm_svm(kvm)->sev_info;

And if we do the above s/dst_//, do it here as well.

> @@ -1633,7 +1675,7 @@ int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
>  	if (ret)
>  		goto out_fput;
>  
> -	if (!sev_guest(source_kvm) || sev_es_guest(source_kvm)) {
> +	if (!sev_guest(source_kvm)) {
>  		ret = -EINVAL;
>  		goto out_source;
>  	}
> @@ -1644,6 +1686,12 @@ int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
>  	if (ret)
>  		goto out_source_vcpu;
>  
> +	if (sev_es_guest(source_kvm)) {
> +		ret = sev_es_migrate_from(kvm, source_kvm);
> +		if (ret)
> +			goto out_source_vcpu;
> +	}
> +
>  	sev_migrate_from(dst_sev, &to_kvm_svm(source_kvm)->sev_info);
>  	kvm_for_each_vcpu (i, vcpu, source_kvm) {
>  		kvm_vcpu_reset(vcpu, /* init_event= */ false);
> -- 
> 2.33.0.1079.g6e70778dc9-goog
>
diff mbox series

Patch

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 2c2f724c9096..d8ce93fd1129 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1605,6 +1605,48 @@  static void sev_migrate_from(struct kvm_sev_info *dst,
 	list_replace_init(&src->regions_list, &dst->regions_list);
 }
 
+static int sev_es_migrate_from(struct kvm *dst, struct kvm *src)
+{
+	int i;
+	struct kvm_vcpu *dst_vcpu, *src_vcpu;
+	struct vcpu_svm *dst_svm, *src_svm;
+
+	if (atomic_read(&src->online_vcpus) != atomic_read(&dst->online_vcpus))
+		return -EINVAL;
+
+	kvm_for_each_vcpu(i, src_vcpu, src) {
+		if (!src_vcpu->arch.guest_state_protected)
+			return -EINVAL;
+	}
+
+	kvm_for_each_vcpu(i, src_vcpu, src) {
+		src_svm = to_svm(src_vcpu);
+		dst_vcpu = kvm_get_vcpu(dst, i);
+		dst_svm = to_svm(dst_vcpu);
+
+		/*
+		 * Transfer VMSA and GHCB state to the destination.  Nullify and
+		 * clear source fields as appropriate, the state now belongs to
+		 * the destination.
+		 */
+		dst_vcpu->vcpu_id = src_vcpu->vcpu_id;
+		dst_svm->sev_es = src_svm->sev_es;
+		dst_svm->vmcb->control.ghcb_gpa =
+			src_svm->vmcb->control.ghcb_gpa;
+		dst_svm->vmcb->control.vmsa_pa = __pa(dst_svm->sev_es.vmsa);
+		dst_vcpu->arch.guest_state_protected = true;
+
+		memset(&src_svm->sev_es, 0, sizeof(src_svm->sev_es));
+		src_svm->vmcb->control.ghcb_gpa = 0;
+		src_svm->vmcb->control.vmsa_pa = 0;
+		src_vcpu->arch.guest_state_protected = false;
+	}
+	to_kvm_svm(src)->sev_info.es_active = false;
+	to_kvm_svm(dst)->sev_info.es_active = true;
+
+	return 0;
+}
+
 int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
 {
 	struct kvm_sev_info *dst_sev = &to_kvm_svm(kvm)->sev_info;
@@ -1633,7 +1675,7 @@  int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
 	if (ret)
 		goto out_fput;
 
-	if (!sev_guest(source_kvm) || sev_es_guest(source_kvm)) {
+	if (!sev_guest(source_kvm)) {
 		ret = -EINVAL;
 		goto out_source;
 	}
@@ -1644,6 +1686,12 @@  int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
 	if (ret)
 		goto out_source_vcpu;
 
+	if (sev_es_guest(source_kvm)) {
+		ret = sev_es_migrate_from(kvm, source_kvm);
+		if (ret)
+			goto out_source_vcpu;
+	}
+
 	sev_migrate_from(dst_sev, &to_kvm_svm(source_kvm)->sev_info);
 	kvm_for_each_vcpu (i, vcpu, source_kvm) {
 		kvm_vcpu_reset(vcpu, /* init_event= */ false);