Re: [edk2-devel] [PATCH 12/16] OvmfPkg/PlatformPei: Retrieve APIC IDs from the hypervisor

["Gerd Hoffmann" <kraxel@redhat.com>]

On Fri, Jan 26, 2024 at 04:13:11PM -0600, Tom Lendacky wrote:
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4654
> 
> If the hypervisor supports retrieval of the vCPU APIC IDs, retrieve
> them before any APs are actually started. The APIC IDs can be used
> to start the APs for any SEV-SNP guest, but is a requirement for an
> SEV-SNP guest that is running under an SVSM.

> +  ApicIds = AllocateReservedPages ((UINTN)PageCount);

> +  VmgExitStatus = CcExitVmgExit (Ghcb, SVM_EXIT_GET_APIC_IDS, (UINTN)ApicIds, 0);

Ah, you pass a pointer to GHCB_APIC_IDS instead of storing the data
directly in the GHCB.  Scratch the patch #10 comment then.

> +  // Retrieve the APIC IDs if the hypervisor supports it. These will be used
> +  // to always start APs using SNP AP Create.
> +  //
> +  if ((HvFeatures & GHCB_HV_FEATURES_APIC_ID_LIST) == GHCB_HV_FEATURES_APIC_ID_LIST) {
> +    AmdSevSnpGetApicIds ();
> +  }

Acked-by: Gerd Hoffmann <kraxel@redhat.com>

This looks like it does not depend on the SVSM being present,
is this correct?

take care,
  Gerd



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