Re: [PATCH RFC v8 45/56] KVM: SVM: Provide support for SNP_GUEST_REQUEST NAE event

[Alexander Graf]

On 20.02.23 19:38, Michael Roth wrote:
> From: Brijesh Singh <brijesh.singh@xxxxxxx>
>
> Version 2 of GHCB specification added the support for two SNP Guest
> Request Message NAE events. The events allows for an SEV-SNP guest to
> make request to the SEV-SNP firmware through hypervisor using the
> SNP_GUEST_REQUEST API define in the SEV-SNP firmware specification.
>
> The SNP_EXT_GUEST_REQUEST is similar to SNP_GUEST_REQUEST with the
> difference of an additional certificate blob that can be passed through
> the SNP_SET_CONFIG ioctl defined in the CCP driver. The CCP driver
> provides snp_guest_ext_guest_request() that is used by the KVM to get
> both the report and certificate data at once.
>
> Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
> Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
> Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
> ---
>   arch/x86/kvm/svm/sev.c | 185 +++++++++++++++++++++++++++++++++++++++--
>   arch/x86/kvm/svm/svm.h |   2 +
>   2 files changed, 181 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 197b1f904567..92179614102e 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -327,6 +327,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
>                  if (ret)
>                          goto e_free;
>
> +               mutex_init(&sev->guest_req_lock);
>                  ret = sev_snp_init(&argp->error, false);
>          } else {
>                  ret = sev_platform_init(&argp->error);
> @@ -2059,23 +2060,34 @@ int sev_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd)
>    */
>   static void *snp_context_create(struct kvm *kvm, struct kvm_sev_cmd *argp)
>   {
> +       struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
>          struct sev_data_snp_addr data = {};
> -       void *context;
> +       void *context, *certs_data;
>          int rc;
>
> +       /* Allocate memory used for the certs data in SNP guest request */
> +       certs_data = kzalloc(SEV_FW_BLOB_MAX_SIZE, GFP_KERNEL_ACCOUNT);
> +       if (!certs_data)
> +               return NULL;


I don't understand why this is part of the context creation, which again 
is part of the KVM_SEV_SNP_LAUNCH_START op. Would you mind to create a 
separate op for this and then check later on while you use the buffer 
whether it was ever allocated?


Alex





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