Re: [PATCH] vfio/type1: Fix vfio_find_dma_valid return

[Alex Williamson <alex.williamson@redhat.com>]

On Fri, 20 Aug 2021 11:44:01 -0700
Anthony Yznaga <anthony.yznaga@oracle.com> wrote:

> On 8/20/21 9:24 AM, Alex Williamson wrote:
> > On Thu, 19 Aug 2021 16:53:57 -0700
> > Anthony Yznaga <anthony.yznaga@oracle.com> wrote:
> >  
> >> Fix vfio_find_dma_valid to return WAITED on success if it was necessary
> >> to wait which mean iommu lock was dropped and reacquired.  This allows
> >> vfio_iommu_type1_pin_pages to recheck vaddr_invalid_count and possibly
> >> avoid the checking the validity of every vaddr in its list.
> >>
> >> Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
> >> ---
> >>  drivers/vfio/vfio_iommu_type1.c | 5 +++--
> >>  1 file changed, 3 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> >> index a3e925a41b0d..7ca8c4e95da4 100644
> >> --- a/drivers/vfio/vfio_iommu_type1.c
> >> +++ b/drivers/vfio/vfio_iommu_type1.c
> >> @@ -612,6 +612,7 @@ static int vfio_find_dma_valid(struct vfio_iommu *iommu, dma_addr_t start,
> >>  			       size_t size, struct vfio_dma **dma_p)
> >>  {
> >>  	int ret;
> >> +	int waited = 0;
> >>  
> >>  	do {
> >>  		*dma_p = vfio_find_dma(iommu, start, size);
> >> @@ -620,10 +621,10 @@ static int vfio_find_dma_valid(struct vfio_iommu *iommu, dma_addr_t start,
> >>  		else if (!(*dma_p)->vaddr_invalid)
> >>  			ret = 0;
> >>  		else
> >> -			ret = vfio_wait(iommu);
> >> +			ret = waited = vfio_wait(iommu);
> >>  	} while (ret > 0);
> >>  
> >> -	return ret;
> >> +	return ret ? ret : waited;
> >>  }
> >>  
> >>  /*  
> > How about...
> >
> > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> > index 0b4f7c174c7a..0e9217687f5c 100644
> > --- a/drivers/vfio/vfio_iommu_type1.c
> > +++ b/drivers/vfio/vfio_iommu_type1.c
> > @@ -612,17 +612,17 @@ static int vfio_wait(struct vfio_iommu *iommu)
> >  static int vfio_find_dma_valid(struct vfio_iommu *iommu, dma_addr_t start,
> >  			       size_t size, struct vfio_dma **dma_p)
> >  {
> > -	int ret;
> > +	int ret = 0;
> >  
> >  	do {
> >  		*dma_p = vfio_find_dma(iommu, start, size);
> >  		if (!*dma_p)
> > -			ret = -EINVAL;
> > +			return -EINVAL;
> >  		else if (!(*dma_p)->vaddr_invalid)
> > -			ret = 0;
> > +			return ret;
> >  		else
> >  			ret = vfio_wait(iommu);
> > -	} while (ret > 0);
> > +	} while (ret == WAITED);
> >  
> >  	return ret;
> >  }
> >  
> 
> Even better.  Should I send a new patch?

That would be preferable, otherwise at least a sign-off or reviewed-by
for the newer version.  Thanks,

Alex