Re: [PATCH] vdpa_sim: Fix incorrect size passed to alloc_iova()

Re: [PATCH] vdpa_sim: Fix incorrect size passed to alloc_iova()

[Stefano Garzarella]

On Mon, Aug 09, 2021 at 02:02:57PM +0800, Xie Yongji wrote:
>The size passed to alloc_iova() should be the size of
>page frames to allocate rather than size in bytes.
>
>Fixes: 4080fc106750 ("vdpa_sim: use iova module to allocate IOVA addresses")
>Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
>---
> drivers/vdpa/vdpa_sim/vdpa_sim.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>index 14e024de5cbf..1ccf615221fe 100644
>--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
>+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>@@ -137,7 +137,8 @@ static dma_addr_t vdpasim_map_range(struct vdpasim *vdpasim, phys_addr_t paddr,
> 	int ret;
>
> 	/* We set the limit_pfn to the maximum (ULONG_MAX - 1) */
>-	iova = alloc_iova(&vdpasim->iova, size, ULONG_MAX - 1, true);
>+	iova = alloc_iova(&vdpasim->iova, size >> iova_shift(&vdpasim->iova),
>+			  ULONG_MAX - 1, true);
> 	if (!iova)
> 		return DMA_MAPPING_ERROR;
>
>-- 
>2.11.0
>

We invoked init_iova_domain() with granularity = 1, so it should be 
correct to use the size in bytes.

However, in order to avoid future bugs if we change granularity, I agree 
that it's better to use iova_shift():

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

Thanks,
Stefano

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Re: [PATCH] vdpa_sim: Fix incorrect size passed to alloc_iova()

[Michael S. Tsirkin]

On Mon, Aug 09, 2021 at 05:18:13PM +0800, Yongji Xie wrote:
> On Mon, Aug 9, 2021 at 5:04 PM Stefano Garzarella <sgarzare@redhat.com> wrote:
> >
> > On Mon, Aug 09, 2021 at 02:02:57PM +0800, Xie Yongji wrote:
> > >The size passed to alloc_iova() should be the size of
> > >page frames to allocate rather than size in bytes.
> > >
> > >Fixes: 4080fc106750 ("vdpa_sim: use iova module to allocate IOVA addresses")
> > >Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
> > >---
> > > drivers/vdpa/vdpa_sim/vdpa_sim.c | 3 ++-
> > > 1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > >diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> > >index 14e024de5cbf..1ccf615221fe 100644
> > >--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
> > >+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> > >@@ -137,7 +137,8 @@ static dma_addr_t vdpasim_map_range(struct vdpasim *vdpasim, phys_addr_t paddr,
> > >       int ret;
> > >
> > >       /* We set the limit_pfn to the maximum (ULONG_MAX - 1) */
> > >-      iova = alloc_iova(&vdpasim->iova, size, ULONG_MAX - 1, true);
> > >+      iova = alloc_iova(&vdpasim->iova, size >> iova_shift(&vdpasim->iova),
> > >+                        ULONG_MAX - 1, true);
> > >       if (!iova)
> > >               return DMA_MAPPING_ERROR;
> > >
> > >--
> > >2.11.0
> > >
> >
> > We invoked init_iova_domain() with granularity = 1, so it should be
> > correct to use the size in bytes.
> >
> 
> Oh, yes. I missed the byte granularity.
> 
> Thanks,
> Yongji

Ok pls post with corrected description and dropped Fixes tag.

-- 
MST

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