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From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 19 Apr 2024 13:52:24 +0200
Message-ID: <CABgObfYztTP+qoTa-tuPC8Au-aKhwiBkcvHni4T+n6MCD-P9Dw@mail.gmail.com>
Subject: Re: [PATCH v13 09/26] KVM: SEV: Add KVM_SEV_SNP_LAUNCH_START command
To: Michael Roth <michael.roth@amd.com>
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On Thu, Apr 18, 2024 at 9:42=E2=80=AFPM Michael Roth <michael.roth@amd.com>=
 wrote:
> +/* As defined by SEV-SNP Firmware ABI, under "Guest Policy". */
> +#define SNP_POLICY_MASK_API_MAJOR      GENMASK_ULL(15, 8)
> +#define SNP_POLICY_MASK_API_MINOR      GENMASK_ULL(7, 0)
> +
> +#define SNP_POLICY_MASK_VALID          (SNP_POLICY_MASK_SMT            |=
 \
> +                                        SNP_POLICY_MASK_RSVD_MBO       |=
 \
> +                                        SNP_POLICY_MASK_DEBUG          |=
 \
> +                                        SNP_POLICY_MASK_SINGLE_SOCKET  |=
 \
> +                                        SNP_POLICY_MASK_API_MAJOR      |=
 \
> +                                        SNP_POLICY_MASK_API_MINOR)
> +
> +/* KVM's SNP support is compatible with 1.51 of the SEV-SNP Firmware ABI=
. */
> +#define SNP_POLICY_API_MAJOR           1
> +#define SNP_POLICY_API_MINOR           51

> +static inline bool sev_version_greater_or_equal(u8 major, u8 minor)
> +{
> +       if (major < SNP_POLICY_API_MAJOR)
> +               return true;

Should it perhaps refuse version 0.x? With something like a

#define SNP_POLICY_API_MAJOR_MIN    1

to make it a bit more future proof (and testable).

> +       major =3D (params.policy & SNP_POLICY_MASK_API_MAJOR);

This should be >> 8. Do the QEMU patches not set the API version? :)

Paolo