Messages in this thread | | | Date | Tue, 16 Apr 2024 08:47:54 -0700 | From | Dan Williams <> | Subject | Re: [PATCH v3 09/14] virt: sev-guest: Choose the VMPCK key based on executing VMPL |
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Tom Lendacky wrote: > On 4/15/24 23:54, Dan Williams wrote: > > Hey, Tom, came looking to review the tsm_report changes and noticed > > this... > > > > Tom Lendacky wrote: > >> Currently, the sev-guest driver uses the vmpck-0 key by default. When an > >> SVSM is present the kernel is running at a VMPL other than 0 and the > >> vmpck-0 key is no longer available. So choose the vmpck key based on the > >> active VMPL level. > > > > The module parameter is not mentioned in the changelog. Is it not > > sufficient to always use snp_get_vmpl(), and if not should there be some > > documentation about when to specify vmpck_id? > > It is possible to encounter an issue that causes the vmpck key to be > cleared. In that situation, the guest is allowed to use a vmpck key > associated with a lower VMPL. For that reason, the module parameter was > added to the driver when it was initially created.
Oh, sorry, misread that the module parameter was not new.
> I can update the changelog to mention this.
I guess it is too late now, but a proper sysfs attribute rather than a module parameter would let you do sanity checking on the writes and allow a natural place to document behavior in Documentation/ABI/testing/sysfs-devices-sev-guest.
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