linux-kernel - Re: [PATCH 3/4] crypto: ccp - Refactor out sev_fw

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Message-ID: <CAMkAt6r=KJ3fMGc4mrUeKVzyWjah5KYRU6u7bqTVsHtwfWkcZw@mail.gmail.com>
Date:   Fri, 29 Oct 2021 09:13:41 -0600
From:   Peter Gonda <pgonda@...gle.com>
To:     Tom Lendacky <Thomas.Lendacky@....com>
Cc:     David Rientjes <rientjes@...gle.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Marc Orr <marcorr@...gle.com>, Joerg Roedel <jroedel@...e.de>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        John Allen <john.allen@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Paolo Bonzini <pbonzini@...hat.com>,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] crypto: ccp - Refactor out sev_fw_alloc()

On Fri, Oct 29, 2021 at 7:48 AM Tom Lendacky <thomas.lendacky@....com> wrote:
>
> On 10/28/21 12:57 PM, Peter Gonda wrote:
> > Creates a helper function sev_fw_alloc() which can be used to allocate
> > aligned memory regions for use by the PSP firmware. Currently only used
> > for the SEV-ES TMR region but will be used for the SEV_INIT_EX NV memory
> > region.
> >
> > Signed-off-by: Peter Gonda <pgonda@...gle.com>
> > Acked-by: David Rientjes <rientjes@...gle.com>
> > Cc: Tom Lendacky <thomas.lendacky@....com>
> > Cc: Brijesh Singh <brijesh.singh@....com>
> > Cc: Marc Orr <marcorr@...gle.com>
> > Cc: Joerg Roedel <jroedel@...e.de>
> > Cc: Herbert Xu <herbert@...dor.apana.org.au>
> > Cc: David Rientjes <rientjes@...gle.com>
> > Cc: John Allen <john.allen@....com>
> > Cc: "David S. Miller" <davem@...emloft.net>
> > Cc: Paolo Bonzini <pbonzini@...hat.com> (
> > Cc: linux-crypto@...r.kernel.org
> > Cc: linux-kernel@...r.kernel.org
> > ---
> >   drivers/crypto/ccp/sev-dev.c | 24 +++++++++++++++++-------
> >   1 file changed, 17 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> > index e4bc833949a0..b568ae734857 100644
> > --- a/drivers/crypto/ccp/sev-dev.c
> > +++ b/drivers/crypto/ccp/sev-dev.c
> > @@ -141,6 +141,21 @@ static int sev_cmd_buffer_len(int cmd)
> >       return 0;
> >   }
> >
> > +static void *sev_fw_alloc(unsigned long len)
> > +{
> > +     const int order = get_order(len);
>
> This should be an unsigned int to match the function definition, but is
> probably not needed given the comment below.
>
> > +     struct page *page;
> > +
> > +     if (order > MAX_ORDER-1)
> > +             return NULL;
>
> I believe alloc_pages() already does this check (and provides a warning
> unless requested not to), so this check isn't needed.

Oh I missed that. Removed.

>
> > +
> > +     page = alloc_pages(GFP_KERNEL, order);
>
> Without the above check, you can just replace the 'order' variable with
> 'get_order(len)'.

Moved the get_order() inline here as suggested.

>
> Thanks,
> Tom
>
> > +     if (!page)
> > +             return NULL;
> > +
> > +     return page_address(page);
> > +}
> > +
> >   static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
> >   {
> >       struct psp_device *psp = psp_master;
> > @@ -1076,7 +1091,6 @@ EXPORT_SYMBOL_GPL(sev_issue_cmd_external_user);
> >   void sev_pci_init(void)
> >   {
> >       struct sev_device *sev = psp_master->sev_data;
> > -     struct page *tmr_page;
> >       int error = 0, rc;
> >
> >       if (!sev)
> > @@ -1092,14 +1106,10 @@ void sev_pci_init(void)
> >               sev_get_api_version();
> >
> >       /* Obtain the TMR memory area for SEV-ES use */
> > -     tmr_page = alloc_pages(GFP_KERNEL, get_order(SEV_ES_TMR_SIZE));
> > -     if (tmr_page) {
> > -             sev_es_tmr = page_address(tmr_page);
> > -     } else {
> > -             sev_es_tmr = NULL;
> > +     sev_es_tmr = sev_fw_alloc(SEV_ES_TMR_SIZE);
> > +     if (!sev_es_tmr)
> >               dev_warn(sev->dev,
> >                        "SEV: TMR allocation failed, SEV-ES support unavailable\n");
> > -     }
> >
> >       /* Initialize the platform */
> >       rc = sev_platform_init(&error);
> >