Re: [PATCH] x86/sev: Remove bogus virtual address check

[Alexey Kardashevskiy <aik@amd.com>]

On 1/4/26 18:29, Ard Biesheuvel wrote:
> [ replying a second time since the first one seems to have evaporated -
> apologies if you are seeing two replies that look vaguely but not
> exactly the same]
> 
> On Tue, 31 Mar 2026, at 23:30, Alexey Kardashevskiy wrote:
>> On 1/4/26 00:21, Ard Biesheuvel wrote:
>>> (add Eric back to cc)
>>>
>>> Please keep Eric on cc - I added him for a reason, thanks.
>>>
>>>
>>> On Tue, 31 Mar 2026, at 15:18, Ard Biesheuvel wrote:
>>>> On Tue, 31 Mar 2026, at 15:16, Borislav Petkov wrote:
>>>>> On Fri, Oct 10, 2025 at 05:10:37PM +0200, Ard Biesheuvel wrote:
>>>>>> From: Ard Biesheuvel <ardb@kernel.org>
>>>>>>
>>>>>> The AES-GCM crypto library operates strictly on virtual addresses,
>>>>>> and never performs any H/W offload, and so calling
>>>>>> virt_addr_valid() is not needed.
>>>>>>
> ...
>>>>>
>>>>> This came from:
>>>>>
>>>>>     7ffeb2fc2670 ("x86/sev: Document requirement for linear mapping
>>>>>     of guest request buffers")
>>
>> Nah, this is because of db10cb9b574675402b virt: sevguest: Fix passing
>> a stack buffer as a scatterlist target
>>
> 
> Is that change still needed after
> 
>    f3476bc77057 ("virt: sev-guest: Use AES GCM crypto library")

huh. You're right, looks like it is not, I missed that.

> If not, should we revert db10cb9b574675402b too?

Nah, we do not want these structures on stack anyway (they might get too big in the future).

> Using the crypto API for simple operations where the algorithm is known
> at build time was always a mistake. But moving stack allocations to the
> heap just to placate a clunky API that can only be used meaningfully in
> an asynchronous manner in the first place is just pointless.

True.

Reviewed-by: Alexey Kardashevskiy <aik@amd.com>
Tested-by: Alexey Kardashevskiy <aik@amd.com>

or should I reply with these to the original mail?

Thanks,


-- 
Alexey