Re: [Part1 PATCH v7 13/17] x86/io: Unroll string I/O when SEV is active

Brijesh Singh
2017-10-21T11:27:04Z

Hi Alan,

On 10/20/17 1:39 PM, Alan Cox wrote:
> On Fri, 20 Oct 2017 09:30:55 -0500
> Brijesh Singh <brijesh.singh@amd.com> wrote:
>
>> From: Tom Lendacky <thomas.lendacky@amd.com>
>>
>> Secure Encrypted Virtualization (SEV) does not support string I/O, so
>> unroll the string I/O operation into a loop operating on one element at
>> a time.
> Does this also mean that any firmware running in the virtual machine
> (EFI, BIOS, VGA etc) has to be patched and if so shouldn't that be
> documented somewhere ?

Yes. SEV support has been added to EDK2/OVMF virtual machine bios and we
have similar patch [1].

[1]
https://github.com/tianocore/edk2/commit/b6d11d7c467810ea7f2e2eda46ef0bdc57bf1475

-Brijesh