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    SubjectRe: [PATCH 3/4] crypto: ccp - Refactor out sev_fw_alloc()
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    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@google.com>
    > Acked-by: David Rientjes <rientjes@google.com>
    > Cc: Tom Lendacky <thomas.lendacky@amd.com>
    > Cc: Brijesh Singh <brijesh.singh@amd.com>
    > Cc: Marc Orr <marcorr@google.com>
    > Cc: Joerg Roedel <jroedel@suse.de>
    > Cc: Herbert Xu <herbert@gondor.apana.org.au>
    > Cc: David Rientjes <rientjes@google.com>
    > Cc: John Allen <john.allen@amd.com>
    > Cc: "David S. Miller" <davem@davemloft.net>
    > Cc: Paolo Bonzini <pbonzini@redhat.com> (
    > Cc: linux-crypto@vger.kernel.org
    > Cc: linux-kernel@vger.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.

    > +
    > + page = alloc_pages(GFP_KERNEL, order);

    Without the above check, you can just replace the 'order' variable with
    'get_order(len)'.

    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);
    >

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