Re: [PATCH v3 05/14] virt: sev-guest: Add vmpck_id to snp_guest_dev struct

[Tom Lendacky]

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@xxxxxxx>
> > > ---
> > >    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