On Tue, Sep 30, 2025 at 05:26:59PM +0200, Cédric Le Goater wrote:
> > - }
> > + ret = ioctl(container->fd, VFIO_CHECK_EXTENSION, VFIO_UNMAP_ALL);
>
> Could we introduce an helper to test 'unmap_all' support in the host
> kernel ? The result would be something like :
>
> if (unmap_all) {
> if (vfio_legacy_has_unmap_all(VFIO_IOMMU_LEGACY(bcontainer))) {
> flags = VFIO_DMA_UNMAP_FLAG_ALL;
> } else {
> /* The unmap ioctl doesn't accept a full 64-bit span. */
> Int128 llsize = int128_rshift(int128_2_64(), 1);
> ...
> }
> }
For reference/consideration, the previous approach taken in the vfio-user
series:
https://lore.kernel.org/qemu-devel/[email protected]/
@@ -533,6 +562,11 @@ static bool vfio_legacy_setup(VFIOContainerBase
*bcontainer, Error **errp)
vfio_get_info_iova_range(info, bcontainer);
vfio_get_iommu_info_migration(container, info);
+
+ ret = ioctl(container->fd, VFIO_CHECK_EXTENSION, VFIO_UNMAP_ALL);
+
+ container->unmap_all_supported = (ret != 0);
(I dropped this particular change as part of getting merged.)
regards
john
