linux-kernel - Re: [PATCH v3 05/14] virt: sev-guest: Add vmpck_id to snp_guest

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Message-ID: <100d7145-7307-20fc-2cc9-0c2edd08f3ef@amd.com>
Date:   Wed, 2 Aug 2023 09:42:22 +0530
From:   "Nikunj A. Dadhania" <nikunj@....com>
To:     Tom Lendacky <thomas.lendacky@....com>,
        linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     bp@...en8.de, dionnaglaze@...gle.com, pgonda@...gle.com,
        seanjc@...gle.com, pbonzini@...hat.com
Subject: Re: [PATCH v3 05/14] virt: sev-guest: Add vmpck_id to snp_guest_dev
 struct

On 8/1/2023 10:00 PM, Tom Lendacky wrote:
> On 7/22/23 06:19, Nikunj A Dadhania wrote:
>> Drop vmpck and os_area_msg_seqno pointers so that secret page layout
>> does not need to be exposed to the sev-guest driver after the rework.
>> Instead, add helper APIs to access vmpck and os_area_msg_seqno when
>> needed.
>>
>> Signed-off-by: Nikunj A Dadhania <nikunj@....com>
>> ---
>>   drivers/virt/coco/sev-guest/sev-guest.c | 84 +++++++++++++------------
>>   1 file changed, 43 insertions(+), 41 deletions(-)
>>
>> diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
>> index d4241048b397..8ad43e007d3b 100644
>> --- a/drivers/virt/coco/sev-guest/sev-guest.c
>> +++ b/drivers/virt/coco/sev-guest/sev-guest.c
>> @@ -50,8 +50,7 @@ struct snp_guest_dev {
>>         struct snp_secrets_page_layout *layout;
>>       struct snp_req_data input;
>> -    u32 *os_area_msg_seqno;
>> -    u8 *vmpck;
>> +    unsigned int vmpck_id;
>>   };
>>     static u32 vmpck_id;
>> @@ -67,12 +66,23 @@ static inline unsigned int get_ctx_authsize(struct snp_guest_dev *snp_dev)
>>       return 0;
>>   }
>>   -static bool is_vmpck_empty(struct snp_guest_dev *snp_dev)
>> +static inline u8 *snp_get_vmpck(struct snp_guest_dev *snp_dev)
>> +{
>> +    return snp_dev->layout->vmpck0 + snp_dev->vmpck_id * VMPCK_KEY_LEN;
>> +}
>> +
>> +static inline u32 *snp_get_os_area_msg_seqno(struct snp_guest_dev *snp_dev)
>> +{
>> +    return &snp_dev->layout->os_area.msg_seqno_0 + snp_dev->vmpck_id;
>> +}
>> +
>> +static bool snp_is_vmpck_empty(struct snp_guest_dev *snp_dev)
> 
> I noticed this name change from is_vmpck_empty() to snp_is_vmpck_empty(). Is that in prep for moving, too? Is so, maybe call that out in the commit message.

Yes, will add to the  commit.

> 
>>   {
>>       char zero_key[VMPCK_KEY_LEN] = {0};
>> +    u8 *key = snp_get_vmpck(snp_dev);
>>   -    if (snp_dev->vmpck)
>> -        return !memcmp(snp_dev->vmpck, zero_key, VMPCK_KEY_LEN);
>> +    if (key)
>> +        return !memcmp(key, zero_key, VMPCK_KEY_LEN);
> 
> I believe key can't be NULL, so this check isn't required.

Sure, will update.

Regards
Nikunj