From afe4e376ac5d568367b447ca90c12858d0935b86 Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Mon, 4 Jul 2022 22:10:50 -0300 Subject: vfio: Move IOMMU_CAP_CACHE_COHERENCY test to after we know we have a group The test isn't going to work if a group doesn't exist. Normally this isn't a problem since VFIO isn't going to create a device if there is no group, but the special CONFIG_VFIO_NOIOMMU behavior allows bypassing this prevention. The new cap test effectively forces a group and breaks this config option. Move the cap test to vfio_group_find_or_alloc() which is the earliest time we know we have a group available and thus are not running in noiommu mode. Fixes: e8ae0e140c05 ("vfio: Require that devices support DMA cache coherence") Reported-by: Xiang Chen Tested-by: Xiang Chen Signed-off-by: Jason Gunthorpe Link: https://lore.kernel.org/r/0-v1-e8934b490f36+f4-vfio_cap_fix_jgg@nvidia.com Signed-off-by: Alex Williamson --- drivers/vfio/vfio.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) (limited to 'drivers/vfio/vfio.c') diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 61e71c1154be..e60b06f2ac22 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -549,6 +549,16 @@ static struct vfio_group *vfio_group_find_or_alloc(struct device *dev) if (!iommu_group) return ERR_PTR(-EINVAL); + /* + * VFIO always sets IOMMU_CACHE because we offer no way for userspace to + * restore cache coherency. It has to be checked here because it is only + * valid for cases where we are using iommu groups. + */ + if (!iommu_capable(dev->bus, IOMMU_CAP_CACHE_COHERENCY)) { + iommu_group_put(iommu_group); + return ERR_PTR(-EINVAL); + } + group = vfio_group_get_from_iommu(iommu_group); if (!group) group = vfio_create_group(iommu_group, VFIO_IOMMU); @@ -601,13 +611,6 @@ static int __vfio_register_dev(struct vfio_device *device, int vfio_register_group_dev(struct vfio_device *device) { - /* - * VFIO always sets IOMMU_CACHE because we offer no way for userspace to - * restore cache coherency. - */ - if (!iommu_capable(device->dev->bus, IOMMU_CAP_CACHE_COHERENCY)) - return -EINVAL; - return __vfio_register_dev(device, vfio_group_find_or_alloc(device->dev)); } -- cgit v1.2.3