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

[Ard Biesheuvel]

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@xxxxxxxxxx>
>> 
>> 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.
>> 
>> Cc: Borislav Petkov (AMD) <bp@xxxxxxxxx>
>> Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
>> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
>> ---
>>  arch/x86/coco/sev/core.c | 9 ---------
>>  1 file changed, 9 deletions(-)
>> 
>> diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
>> index 9ae3b11754e6..c4e2de3687a9 100644
>> --- a/arch/x86/coco/sev/core.c
>> +++ b/arch/x86/coco/sev/core.c
>> @@ -2249,15 +2249,6 @@ int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req
>>  	u64 seqno;
>>  	int rc;
>>  
>> -	/*
>> -	 * enc_payload() calls aesgcm_encrypt(), which can potentially offload to HW.
>> -	 * The offload's DMA SG list of data to encrypt has to be in linear mapping.
>> -	 */
>> -	if (!virt_addr_valid(req->req_buf) || !virt_addr_valid(req->resp_buf)) {
>> -		pr_warn("AES-GSM buffers must be in linear mapping");
>> -		return -EINVAL;
>> -	}
>> -
>>  	guard(mutex)(&snp_cmd_mutex);
>>  
>>  	/* Check if the VMPCK is not empty */
>> -- 
>
> This came from:
>
>   7ffeb2fc2670 ("x86/sev: Document requirement for linear mapping of 
> guest request buffers")
>
> and there was some speculation about the potential of using a crypto
> accelerator which wants addresses in linear mapping...
>

Sure, but that speculation was entirely misguided, so we can remove this again.