Re: [RFC PATCH 3/6] i386/sev: initialize SNP context

[Dov Murik]

Hi Brijesh,

On 10/07/2021 0:55, Brijesh Singh wrote:
> When SEV-SNP is enabled, the KVM_SNP_INIT command is used to initialize
> the platform. The command checks whether SNP is enabled in the KVM, if
> enabled then it allocate a new ASID from the SNP pool and calls the

s/allocate/allocates/

> firmware to initialize the all the resources.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
>  target/i386/sev.c      | 24 +++++++++++++++++++++---
>  target/i386/sev_i386.h |  1 +
>  2 files changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git a/target/i386/sev.c b/target/i386/sev.c
> index 6b238ef969..84ae244af0 100644
> --- a/target/i386/sev.c
> +++ b/target/i386/sev.c
> @@ -583,10 +583,17 @@ sev_enabled(void)
>      return !!sev_guest;
>  }
>  
> +bool
> +sev_snp_enabled(void)
> +{
> +    return sev_guest->snp;
> +}
> +
>  bool
>  sev_es_enabled(void)
>  {
> -    return sev_enabled() && (sev_guest->policy & SEV_POLICY_ES);
> +    return sev_snp_enabled() ||
> +           (sev_enabled() && (sev_guest->policy & SEV_POLICY_ES));
>  }
>  

Just making sure I understand:

* sev_enabled() returns true for SEV or newer (SEV or SEV-ES or
  SEV-SNP).
* sev_es_enabled() returns true for SEV-ES or newer (SEV-ES or SEV-SNP).
* sev_snp_enabled() returns true for SEV-SNP or newer (currently only
  SEV-SNP).

Is that indeed the intention?


-Dov


>  uint64_t
> @@ -1008,6 +1015,7 @@ int sev_kvm_init(ConfidentialGuestSupport *cgs, Error 
> **errp)
>      uint32_t ebx;
>      uint32_t host_cbitpos;
>      struct sev_user_data_status status = {};
> +    void *init_args = NULL;
>  
>      if (!sev) {
>          return 0;
> @@ -1061,7 +1069,17 @@ int sev_kvm_init(ConfidentialGuestSupport *cgs, Error 
> **errp)
>      sev->api_major = status.api_major;
>      sev->api_minor = status.api_minor;
>  
> -    if (sev_es_enabled()) {
> +    if (sev_snp_enabled()) {
> +        if (!kvm_kernel_irqchip_allowed()) {
> +            error_report("%s: SEV-SNP guests require in-kernel irqchip 
> support",
> +                         __func__);
> +            goto err;
> +        }
> +
> +        cmd = KVM_SEV_SNP_INIT;
> +        init_args = (void *)&sev->snp_config.init;
> +
> +    } else if (sev_es_enabled()) {
>          if (!kvm_kernel_irqchip_allowed()) {
>              error_report("%s: SEV-ES guests require in-kernel irqchip 
> support",
>                           __func__);
> @@ -1080,7 +1098,7 @@ int sev_kvm_init(ConfidentialGuestSupport *cgs, Error 
> **errp)
>      }
>  
>      trace_kvm_sev_init();
> -    ret = sev_ioctl(sev->sev_fd, cmd, NULL, &fw_error);
> +    ret = sev_ioctl(sev->sev_fd, cmd, init_args, &fw_error);
>      if (ret) {
>          error_setg(errp, "%s: failed to initialize ret=%d fw_error=%d '%s'",
>                     __func__, ret, fw_error, fw_error_to_str(fw_error));
> diff --git a/target/i386/sev_i386.h b/target/i386/sev_i386.h
> index ae6d840478..e0e1a599be 100644
> --- a/target/i386/sev_i386.h
> +++ b/target/i386/sev_i386.h
> @@ -29,6 +29,7 @@
>  #define SEV_POLICY_SEV          0x20
>  
>  extern bool sev_es_enabled(void);
> +extern bool sev_snp_enabled(void);
>  extern uint64_t sev_get_me_mask(void);
>  extern SevInfo *sev_get_info(void);
>  extern uint32_t sev_get_cbit_position(void);
>