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Re: [PATCH v10 10/10] vfio: Don't issue full 2^64 unmap
From: |
Michael S. Tsirkin |
Subject: |
Re: [PATCH v10 10/10] vfio: Don't issue full 2^64 unmap |
Date: |
Fri, 30 Oct 2020 06:25:34 -0400 |
On Thu, Oct 08, 2020 at 03:22:14PM -0600, Alex Williamson wrote:
> On Thu, 8 Oct 2020 19:15:58 +0200
> Jean-Philippe Brucker <jean-philippe@linaro.org> wrote:
>
> > IOMMUs may declare memory regions spanning from 0 to UINT64_MAX. When
> > attempting to deal with such region, vfio_listener_region_del() passes a
> > size of 2^64 to int128_get64() which throws an assertion failure. Even
> > ignoring this, the VFIO_IOMMU_DMA_MAP ioctl cannot handle this size
> > since the size field is 64-bit. Split the request in two.
> >
> > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > ---
> > For me this happens when memory_region_iommu_set_page_size_mask()
> > returns an error because a hotplugged endpoint uses an incompatible page
> > mask. vfio_connect_container() releases the memory listener which calls
> > region_del() with the 2^64 IOMMU region. There are probably other ways
> > to reach this.
> > ---
> > hw/vfio/common.c | 11 +++++++++++
> > 1 file changed, 11 insertions(+)
> >
> > diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> > index e66054b02a7..e90a89c389e 100644
> > --- a/hw/vfio/common.c
> > +++ b/hw/vfio/common.c
> > @@ -797,6 +797,17 @@ static void vfio_listener_region_del(MemoryListener
> > *listener,
> > }
> >
> > if (try_unmap) {
> > + if (llsize == int128_2_64()) {
> > + /* The unmap ioctl doesn't accept a full 64-bit span. */
> > + llsize = int128_rshift(llsize, 1);
> > + ret = vfio_dma_unmap(container, iova, int128_get64(llsize));
> > + if (ret) {
> > + error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", "
> > + "0x%"HWADDR_PRIx") = %d (%m)",
> > + container, iova, int128_get64(llsize), ret);
> > + }
> > + iova += int128_get64(llsize);
> > + }
> > ret = vfio_dma_unmap(container, iova, int128_get64(llsize));
> > if (ret) {
> > error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", "
>
> We're still susceptible that splitting the range in two could result in
> unmap calls that attempt to bisect a mapping that spans both ranges.
> Both unmap calls would fail in that case. I think we could solve this
> more completely with a high water marker, but this probably good enough
> for now.
>
> Acked-by: Alex Williamson <alex.williamson@redhat.com>
Are you merging this then?
If yes
Acked-by: Michael S. Tsirkin <mst@redhat.com>
- Re: [PATCH v10 09/10] virtio-iommu: Set supported page size mask, (continued)
[PATCH v10 08/10] vfio: Set IOMMU page size as per host supported page size, Jean-Philippe Brucker, 2020/10/08
Re: [PATCH v10 08/10] vfio: Set IOMMU page size as per host supported page size, Auger Eric, 2020/10/16
[PATCH v10 10/10] vfio: Don't issue full 2^64 unmap, Jean-Philippe Brucker, 2020/10/08
Re: [PATCH v10 10/10] vfio: Don't issue full 2^64 unmap, Auger Eric, 2020/10/16
Re: [PATCH v10 00/10] virtio-iommu: VFIO integration, Auger Eric, 2020/10/16
Re: [PATCH v10 00/10] virtio-iommu: VFIO integration, Michael S. Tsirkin, 2020/10/30