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

[Stefano Garzarella <sgarzare@redhat.com>]

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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