On 09/29 01:34, Alex Williamson wrote:
> On Mon, 28 Sep 2020 15:05:05 -0500
> Wei Huang wrote:
>
> > Add support to sync the IOVA-to-GPA translation at the time of IOMMU
> > page invalidation. This function is called when two IOMMU commands,
> > AMDVI_CMD_INVAL_AMDVI_PAGES and AMDVI_CMD_INVAL_AMDVI_ALL, are
> > intercepted. Address space notifiers are called accordingly.
> >
> > Co-developed-by: Wei Huang
> > Signed-off-by: Suravee Suthikulpanit
> > ---
> > hw/i386/amd_iommu.c | 177
> > hw/i386/amd_iommu.h | 10 +++
> > hw/vfio/common.c| 3 +-
> > 3 files changed, 189 insertions(+), 1 deletion(-)
> ...
> > diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> > index 13471ae29436..243216499ce0 100644
> > --- a/hw/vfio/common.c
> > +++ b/hw/vfio/common.c
> > @@ -346,7 +346,8 @@ static int vfio_dma_map(VFIOContainer *container,
> > hwaddr iova,
> > * the VGA ROM space.
> > */
> > if (ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map) == 0 ||
> > -(errno == EBUSY && vfio_dma_unmap(container, iova, size) == 0 &&
> > +((errno == EEXIST || errno == EBUSY) &&
> > + vfio_dma_unmap(container, iova, size) == 0 &&
> > ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map) == 0)) {
> > return 0;
> > }
>
>
> This seems like it should be a separate patch. AFAICT the commit log
> doesn't even hint at why this change is necessary. I think the -EBUSY
> error pre-dates vIOMMU as well. Responding the same for an -EEXIST
> almost suggests a coherency issue between QEMU and the kernel, or a
> direct mapping replacement without an invalidation, which doesn't seem
> to be what this patch is implementing. Thanks,
I went back to check it. Removing this checking code (original code) didn't
trigger any issues with Intel 10G passthru NIC. I think this was from the
residual debugging code when we started to implement it. Sorry for the
confusion. I will remove this code in V2 with more tests.
-Wei
>
> Alex
>
