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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <cae0b2e9-12e6-9d2c-506e-0dc6f72988a4@amd.com>
Date:   Wed, 2 Aug 2023 11:55:51 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     nikunj@....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 8/1/23 23:12, Nikunj A. Dadhania wrote:
> 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.

Ah, although I noticed that when the various functions are moved over to 
the other file, the key return value can be NULL, so probably not worth 
changing here.

Thanks,
Tom

> 
> Regards
> Nikunj
>