Re: [PATCH 08/10] KVM: SEV: define VM types for SEV and SEV-ES

From: Michael Roth
Date: Wed Feb 14 2024 - 20:23:42 EST

On Fri, Feb 09, 2024 at 01:37:40PM -0500, Paolo Bonzini wrote:
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
> Documentation/virt/kvm/api.rst | 2 ++
> arch/x86/include/uapi/asm/kvm.h | 2 ++
> arch/x86/kvm/svm/sev.c | 18 +++++++++++++++++-
> arch/x86/kvm/svm/svm.c | 11 +++++++++++
> arch/x86/kvm/svm/svm.h | 2 ++
> arch/x86/kvm/x86.c | 4 ++++
> 6 files changed, 38 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index 3ec0b7a455a0..bf957bb70e4b 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -8790,6 +8790,8 @@ means the VM type with value @n is supported. Possible values of @n are::
>
> #define KVM_X86_DEFAULT_VM 0
> #define KVM_X86_SW_PROTECTED_VM 1
> + #define KVM_X86_SEV_VM 8
> + #define KVM_X86_SEV_ES_VM 10
>
> 9. Known KVM API problems
> =========================
> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
> index 6c74db23257e..7c46e96cfe62 100644
> --- a/arch/x86/include/uapi/asm/kvm.h
> +++ b/arch/x86/include/uapi/asm/kvm.h
> @@ -854,5 +854,7 @@ struct kvm_hyperv_eventfd {
>
> #define KVM_X86_DEFAULT_VM 0
> #define KVM_X86_SW_PROTECTED_VM (KVM_X86_DEFAULT_VM | __KVM_X86_PRIVATE_MEM_TYPE)
> +#define KVM_X86_SEV_VM 8

Hmm... would it make sense to decouple the VM types and their associated
capabilities? Only bit 2 is left in the lower range after this, and using any
bits beyond TDX's bit 4 risks overflowing check_extension ioctl's 32-bit return
value. Maybe a separate lookup table instead?

> +#define KVM_X86_SEV_ES_VM (KVM_X86_SEV_VM | __KVM_X86_PROTECTED_STATE_TYPE)
>
> #endif /* _ASM_X86_KVM_H */
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 712bfbc0028a..acf5c45ef14e 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -260,6 +260,9 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
> if (kvm->created_vcpus)
> return -EINVAL;
>
> + if (kvm->arch.vm_type != KVM_X86_DEFAULT_VM)
> + return -EINVAL;
> +
> ret = -EBUSY;
> if (unlikely(sev->active))
> return ret;
> @@ -279,6 +282,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
>
> INIT_LIST_HEAD(&sev->regions_list);
> INIT_LIST_HEAD(&sev->mirror_vms);
> + sev->need_init = false;
>
> kvm_set_apicv_inhibit(kvm, APICV_INHIBIT_REASON_SEV);
>
> @@ -1814,7 +1818,8 @@ int sev_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd)
> if (ret)
> goto out_fput;
>
> - if (sev_guest(kvm) || !sev_guest(source_kvm)) {
> + if (kvm->arch.vm_type != source_kvm->arch.vm_type ||
> + sev_guest(kvm) || !sev_guest(source_kvm)) {
> ret = -EINVAL;
> goto out_unlock;
> }
> @@ -2135,6 +2140,7 @@ int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd)
> mirror_sev->asid = source_sev->asid;
> mirror_sev->fd = source_sev->fd;
> mirror_sev->es_active = source_sev->es_active;
> + mirror_sev->need_init = false;
> mirror_sev->handle = source_sev->handle;
> INIT_LIST_HEAD(&mirror_sev->regions_list);
> INIT_LIST_HEAD(&mirror_sev->mirror_vms);
> @@ -3192,3 +3198,13 @@ void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector)
>
> ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, 1);
> }
> +
> +bool sev_is_vm_type_supported(unsigned long type)
> +{
> + if (type == KVM_X86_SEV_VM)
> + return sev_enabled;
> + if (type == KVM_X86_SEV_ES_VM)
> + return sev_es_enabled;
> +
> + return false;
> +}
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 392b9c2e2ce1..87541c84d07e 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -4087,6 +4087,11 @@ static void svm_cancel_injection(struct kvm_vcpu *vcpu)
>
> static int svm_vcpu_pre_run(struct kvm_vcpu *vcpu)
> {
> + struct kvm_sev_info *sev = &to_kvm_svm(vcpu->kvm)->sev_info;
> +
> + if (sev->need_init)
> + return -EINVAL;
> +
> return 1;
> }
>
> @@ -4888,6 +4893,11 @@ static void svm_vm_destroy(struct kvm *kvm)
>
> static int svm_vm_init(struct kvm *kvm)
> {
> + if (kvm->arch.vm_type) {
> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> + sev->need_init = true;
> + }
> +
> if (!pause_filter_count || !pause_filter_thresh)
> kvm->arch.pause_in_guest = true;
>
> @@ -4914,6 +4924,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
> .vcpu_free = svm_vcpu_free,
> .vcpu_reset = svm_vcpu_reset,
>
> + .is_vm_type_supported = sev_is_vm_type_supported,
> .vm_size = sizeof(struct kvm_svm),
> .vm_init = svm_vm_init,
> .vm_destroy = svm_vm_destroy,
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index 864c782eaa58..63be26d4a024 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -79,6 +79,7 @@ enum {
> struct kvm_sev_info {
> bool active; /* SEV enabled guest */
> bool es_active; /* SEV-ES enabled guest */
> + bool need_init; /* waiting for SEV_INIT2 */

Seems like this should be a separate patch.

-Mike

> unsigned int asid; /* ASID used for this guest */
> unsigned int handle; /* SEV firmware handle */
> int fd; /* SEV device fd */
> @@ -696,6 +697,7 @@ 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 vcpu_svm *svm, struct sev_es_save_area *hostsa);
> void sev_es_unmap_ghcb(struct vcpu_svm *svm);
> +bool sev_is_vm_type_supported(unsigned long type);
>
> /* vmenter.S */
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index c89ddaa1e09f..dfc66ee091a1 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4795,6 +4795,10 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> r = BIT(KVM_X86_DEFAULT_VM);
> if (kvm_is_vm_type_supported(KVM_X86_SW_PROTECTED_VM))
> r |= BIT(KVM_X86_SW_PROTECTED_VM);
> + if (kvm_is_vm_type_supported(KVM_X86_SEV_VM))
> + r |= BIT(KVM_X86_SEV_VM);
> + if (kvm_is_vm_type_supported(KVM_X86_SEV_ES_VM))
> + r |= BIT(KVM_X86_SEV_ES_VM);
> break;
> default:
> break;
> --
> 2.39.0
>
>