Re: [PATCH v1 2/3] iommu: Fix an issue in iommu_page_response() flags check

Yi Sun
2020-10-29T06:34:49Z

On 20-10-28 10:13:56, Jean-Philippe Brucker wrote:
> Hi,
>
> On Wed, Oct 28, 2020 at 09:36:57AM +0800, Yi Sun wrote:
> > From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> >
> > original code fails when LAST_PAGE is set in flags.
>
> LAST_PAGE is not documented to be a valid flags for page_response.
> So isn't failing the right thing to do?
>
> >
> > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> > Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
> > ---
> > drivers/iommu/iommu.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> > index 8c470f4..053cec3 100644
> > --- a/drivers/iommu/iommu.c
> > +++ b/drivers/iommu/iommu.c
> > @@ -1200,9 +1200,11 @@ int iommu_page_response(struct device *dev,
> > return -EINVAL;
> >
> > if (msg->version != IOMMU_PAGE_RESP_VERSION_1 ||
> > - msg->flags & ~IOMMU_PAGE_RESP_PASID_VALID)
> > + !(msg->flags & IOMMU_PAGE_RESP_PASID_VALID)) {
>
> It should be OK not to have PASID_VALID set, we're just checking for
> undefined flags here.
>
Thanks! You are right. Per published spec, we should not care LAST_PAGE
for page_response. I will remove this patch in next version.

> Thanks,
> Jean
>
> > + dev_warn_ratelimited(dev, "%s:Invalid ver %x: flags %x\n",
> > + __func__, msg->version, msg->flags);
> > return -EINVAL;
> > -
> > + }
> > /* Only send response if there is a fault report pending */
> > mutex_lock(&param->fault_param->lock);
> > if (list_empty(&param->fault_param->faults)) {
> > --
> > 2.7.4
> >
> > _______________________________________________
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> > iommu@lists.linux-foundation.org
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