Re: [PATCH v4 2/9] target/i386: SEV: Ensure SEV features are only set through qemu cli or IGVM

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, May 20, 2026 at 06:57:55PM +0530, Naveen N Rao (AMD) wrote:
> In preparation for qemu being able to set SEV features through the cli,
> add a check to ensure that SEV features are not also set if using IGVM
> files.
> 
> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Naveen N Rao (AMD) <naveen@kernel.org>
> ---
>  target/i386/sev.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/target/i386/sev.c b/target/i386/sev.c
> index 22c350fe14b7..641a295c42b7 100644
> --- a/target/i386/sev.c
> +++ b/target/i386/sev.c
> @@ -1908,6 +1908,16 @@ static int sev_common_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
>           * as SEV_STATE_UNINIT.
>           */
>          if (x86machine->igvm) {
> +            /*
> +             * Test only the user-set SEV features by masking out
> +             * SVM_SEV_FEAT_SNP_ACTIVE which is set by default.
> +             */
> +            if (sev_common->sev_features & ~SVM_SEV_FEAT_SNP_ACTIVE) {
> +                error_setg(errp,
> +                           "%s: SEV features can't be specified when using IGVM files",
> +                           __func__);

IMHO, including __func__ in error messages is redundant / undesirable.
The error msg  alone should be sufficient to diagnose problems.Perhaps
we should include the actual feature values though

                           "SEV features 0x%x can't be specified when using IGVM files",
                           sev_common->sev_features & ~SVM_SEV_FEAT_SNP_ACTIVE);

this case, however, you should report which features are not permitted

> +                return -1;
> +            }
>              if (IGVM_CFG_GET_CLASS(x86machine->igvm)
>                      ->process(x86machine->igvm, machine, true, errp) == -1) {
>                  return -1;
> -- 
> 2.54.0
> 
> 

With regards,
Daniel
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