On 6/8/26 09:41, Jörg Rödel wrote:
> From: Melody Wang <[email protected]>
>
> To support Restricted Injection, the SEV-SNP guest must register a doorbell
> page for use with #HV. This is done using the #HV doorbell page NAE event.
>
> This event consists of four actions: GET_PREFERRED, SET, QUERY, CLEAR.
> Implement it per the GHCB specification.
>
> Co-developed-by: Thomas Lendacky <[email protected]>
> Signed-off-by: Thomas Lendacky <[email protected]>
> Signed-off-by: Melody Wang <[email protected]>
> Signed-off-by: Joerg Roedel <[email protected]>
> ---
> arch/x86/include/uapi/asm/svm.h | 5 +++
> arch/x86/kvm/svm/sev.c | 71 +++++++++++++++++++++++++++++++++
> arch/x86/kvm/svm/svm.c | 3 ++
> arch/x86/kvm/svm/svm.h | 2 +
> 4 files changed, 81 insertions(+)
>
> diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h
> index 010a45c9f614..d84a13ac4627 100644
> --- a/arch/x86/include/uapi/asm/svm.h
> +++ b/arch/x86/include/uapi/asm/svm.h
> @@ -117,6 +117,11 @@
> #define SVM_VMGEXIT_AP_CREATE_ON_INIT 0
> #define SVM_VMGEXIT_AP_CREATE 1
> #define SVM_VMGEXIT_AP_DESTROY 2
> +#define SVM_VMGEXIT_HVDB_PAGE 0x80000014ull
> +#define SVM_VMGEXIT_HVDB_GET_PREFERRED 0
> +#define SVM_VMGEXIT_HVDB_SET 1
> +#define SVM_VMGEXIT_HVDB_QUERY 2
> +#define SVM_VMGEXIT_HVDB_CLEAR 3
> #define SVM_VMGEXIT_SNP_RUN_VMPL 0x80000018ull
> #define SVM_VMGEXIT_SAVIC 0x8000001aull
> #define SVM_VMGEXIT_SAVIC_REGISTER_GPA 0
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 6c6a6d663e29..b9ad1169cb2c 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -3522,6 +3522,10 @@ static int sev_es_validate_vmgexit(struct vcpu_svm
> *svm)
> control->exit_info_1 == control->exit_info_2)
> goto vmgexit_err;
> break;
> + case SVM_VMGEXIT_HVDB_PAGE:
> + if (!is_sev_snp_guest(vcpu))
> + goto vmgexit_err;
> + break;
> default:
> reason = GHCB_ERR_INVALID_EVENT;
> goto vmgexit_err;
> @@ -4341,6 +4345,65 @@ static int snp_handle_ext_guest_req(struct vcpu_svm
> *svm, gpa_t req_gpa, gpa_t r
> return 1; /* resume guest */
> }
>
> +static int sev_snp_hv_doorbell_page(struct vcpu_svm *svm)
> +{
> + struct kvm_vcpu *vcpu = &svm->vcpu;
> + struct kvm_host_map hvdb_map;
> + gpa_t hvdb_gpa;
> + u64 request;
> +
> + if (!is_sev_snp_guest(vcpu))
> + return -EINVAL;
> +
> + request = svm->vmcb->control.exit_info_1;
> + hvdb_gpa = svm->vmcb->control.exit_info_2;
> +
> + switch (request) {
> + case SVM_VMGEXIT_HVDB_GET_PREFERRED:
> + ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, ~0ULL);
> + break;
> + case SVM_VMGEXIT_HVDB_SET:
> + svm->sev_es.hvdb_gpa = INVALID_PAGE;
> +
> + if (!PAGE_ALIGNED(hvdb_gpa)) {
> + vcpu_unimpl(vcpu, "vmgexit: unaligned #HV doorbell page
> address [%#llx] from guest\n",
> + hvdb_gpa);
> + return -EINVAL;
> + }
> +
> + if (!page_address_valid(vcpu, hvdb_gpa)) {
> + vcpu_unimpl(vcpu, "vmgexit: invalid #HV doorbell page
> address [%#llx] from guest\n",
> + hvdb_gpa);
> + return -EINVAL;
> + }
> +
> + /* Map and unmap the GPA just to be sure the GPA is valid */
> + if (kvm_vcpu_map(vcpu, gpa_to_gfn(hvdb_gpa), &hvdb_map)) {
> + vcpu_unimpl(vcpu, "vmgexit: error mapping #HV doorbell
> page [%#llx] from guest\n",
> + hvdb_gpa);
> + return -EINVAL;
> + }
> + kvm_vcpu_unmap(vcpu, &hvdb_map);
> +
> + svm->sev_es.hvdb_gpa = hvdb_gpa;
> + fallthrough;
> + case SVM_VMGEXIT_HVDB_QUERY:
> + ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, svm->sev_es.hvdb_gpa);
> + break;
> + case SVM_VMGEXIT_HVDB_CLEAR:
> + svm->sev_es.hvdb_gpa = INVALID_PAGE;
> + break;
> + default:
> + svm->sev_es.hvdb_gpa = INVALID_PAGE;
> +
> + vcpu_unimpl(vcpu, "vmgexit: invalid #HV doorbell page request
> [%#llx] from guest\n",
> + request);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
> {
> struct vmcb_control_area *control = &svm->vmcb->control;
> @@ -4617,6 +4680,14 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
> case SVM_VMGEXIT_EXT_GUEST_REQUEST:
> ret = snp_handle_ext_guest_req(svm, control->exit_info_1,
> control->exit_info_2);
> break;
> + case SVM_VMGEXIT_HVDB_PAGE:
> + if (sev_snp_hv_doorbell_page(svm)) {
> + ghcb_set_sw_exit_info_1(svm->sev_es.ghcb, 2);
> + ghcb_set_sw_exit_info_2(svm->sev_es.ghcb,
> GHCB_ERR_INVALID_INPUT);
> + }
> +
> + ret = 1;
> + break;
> case SVM_VMGEXIT_UNSUPPORTED_EVENT:
> vcpu_unimpl(vcpu,
> "vmgexit: unsupported event - exit_info_1=%#llx,
> exit_info_2=%#llx\n",
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index e02a38da5296..7981e7583384 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -1277,6 +1277,9 @@ static void __svm_vcpu_reset(struct kvm_vcpu *vcpu)
>
> svm->nmi_masked = false;
> svm->awaiting_iret_completion = false;
> +
> + if (is_sev_es_guest(vcpu))
Shouldn't this be is_sev_snp_guest() ?
Thanks,
Tom
> + svm->sev_es.hvdb_gpa = INVALID_PAGE;
> }
>
> static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index 5137416be593..fb956c37c941 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -270,6 +270,8 @@ struct vcpu_sev_es_state {
> gpa_t snp_vmsa_gpa;
> bool snp_ap_waiting_for_reset;
> bool snp_has_guest_vmsa;
> +
> + gpa_t hvdb_gpa;
> };
>
> struct vcpu_svm {
