Re: [PATCH v2 2/2] sev: update sev-inject-launch-secret to make gpa optional

[Dr. David Alan Gilbert]

* James Bottomley (jejb@linux.ibm.com) wrote:
> If the gpa isn't specified, it's value is extracted from the OVMF
> properties table located below the reset vector (and if this doesn't
> exist, an error is returned).  OVMF has defined the GUID for the SEV
> secret area as 4c2eb361-7d9b-4cc3-8081-127c90d3d294 and the format of
> the <data> is: <base>|<size> where both are uint32_t.  We extract
> <base> and use it as the gpa for the injection.
> 
> Note: it is expected that the injected secret will also be GUID
> described but since qemu can't interpret it, the format is left
> undefined here.
> 
> Signed-off-by: James Bottomley <jejb@linux.ibm.com>
> 
> ---
> 
> v2: fix line length warning, add more comments about sev area
> ---
>  qapi/misc-target.json |  2 +-
>  target/i386/monitor.c | 27 ++++++++++++++++++++++++++-
>  2 files changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/qapi/misc-target.json b/qapi/misc-target.json
> index 06ef8757f0..0c7491cd82 100644
> --- a/qapi/misc-target.json
> +++ b/qapi/misc-target.json
> @@ -216,7 +216,7 @@
>  #
>  ##
>  { 'command': 'sev-inject-launch-secret',
> -  'data': { 'packet-header': 'str', 'secret': 'str', 'gpa': 'uint64' },
> +  'data': { 'packet-header': 'str', 'secret': 'str', '*gpa': 'uint64' },
>    'if': 'defined(TARGET_I386)' }
>  
>  ##
> diff --git a/target/i386/monitor.c b/target/i386/monitor.c
> index 1bc91442b1..11bdb04155 100644
> --- a/target/i386/monitor.c
> +++ b/target/i386/monitor.c
> @@ -34,6 +34,7 @@
>  #include "sev_i386.h"
>  #include "qapi/qapi-commands-misc-target.h"
>  #include "qapi/qapi-commands-misc.h"
> +#include "hw/i386/pc.h"
>  
>  /* Perform linear address sign extension */
>  static hwaddr addr_canonical(CPUArchState *env, hwaddr addr)
> @@ -730,9 +731,33 @@ SevCapability *qmp_query_sev_capabilities(Error **errp)
>      return sev_get_capabilities(errp);
>  }
>  
> +#define SEV_SECRET_GUID "4c2eb361-7d9b-4cc3-8081-127c90d3d294"
> +struct sev_secret_area {
> +    uint32_t base;
> +    uint32_t size;
> +};
> +
>  void qmp_sev_inject_launch_secret(const char *packet_hdr,
> -                                  const char *secret, uint64_t gpa,
> +                                  const char *secret,
> +                                  bool has_gpa, uint64_t gpa,
>                                    Error **errp)
>  {
> +    if (!has_gpa) {
> +        uint8_t *data;
> +        struct sev_secret_area *area;
> +
> +        /*
> +         * not checking length means that this area can't be versioned
> +         * by length and would have to be replaced if updated
> +         */

Can you just explain that a bit more?

> +        if (!pc_system_ovmf_table_find(SEV_SECRET_GUID, &data, NULL)) {
> +            error_setg(errp, "SEV: no secret area found in OVMF,"
> +                       " gpa must be specified.");
> +            return;
> +        }
> +        area = (struct sev_secret_area *)data;
> +        gpa = area->base;
> +    }
> +
>      sev_inject_launch_secret(packet_hdr, secret, gpa, errp);

Other than me not understanding that comment, I think we're fine:


Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

>  }
> -- 
> 2.26.2
> 
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK