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

[Yi Sun]

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@xxxxxxxxxxxxxxx>
> > 
> > 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@xxxxxxxxxxxxxxx>
> > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
> > Signed-off-by: Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx>
> > ---
> >  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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