From: Alexey Kardashevskiy <aik@ozlabs.ru>
To: kvm@vger.kernel.org
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
Robin Murphy <robin.murphy@arm.com>,
Lu Baolu <baolu.lu@linux.intel.com>,
Kevin Tian <kevin.tian@intel.com>, Joerg Roedel <jroedel@suse.de>,
Jason Gunthorpe <jgg@ziepe.ca>,
Alex Williamson <alex.williamson@redhat.com>,
kvm-ppc@vger.kernel.org
Subject: [RFC PATCH kernel] vfio: Skip checking for IOMMU_CAP_CACHE_COHERENCY on POWER and more
Date: Fri, 01 Jul 2022 06:17:51 +0000 [thread overview]
Message-ID: <20220701061751.1955857-1-aik@ozlabs.ru> (raw)
VFIO on POWER does not implement iommu_ops and therefore iommu_capable()
always returns false and __iommu_group_alloc_blocking_domain() always
fails.
iommu_group_claim_dma_owner() in setting container fails for the same
reason - it cannot allocate a domain.
This skips the check for platforms supporting VFIO without implementing
iommu_ops which to my best knowledge is POWER only.
This also allows setting container in absence of iommu_ops.
Fixes: 70693f470848 ("vfio: Set DMA ownership for VFIO devices")
Fixes: e8ae0e140c05 ("vfio: Require that devices support DMA cache coherence")
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Not quite sure what the proper small fix is and implementing iommu_ops
on POWER is not going to happen any time soon or ever :-/
---
drivers/vfio/vfio.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 61e71c1154be..71408ab26cd0 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -605,7 +605,8 @@ 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))
+ if (device->dev->bus->iommu_ops &&
+ !iommu_capable(device->dev->bus, IOMMU_CAP_CACHE_COHERENCY))
return -EINVAL;
return __vfio_register_dev(device,
@@ -934,7 +935,7 @@ static void __vfio_group_unset_container(struct vfio_group *group)
driver->ops->detach_group(container->iommu_data,
group->iommu_group);
- if (group->type = VFIO_IOMMU)
+ if (group->type = VFIO_IOMMU && iommu_group_dma_owner_claimed(group->iommu_group))
iommu_group_release_dma_owner(group->iommu_group);
group->container = NULL;
@@ -1010,9 +1011,8 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd)
}
if (group->type = VFIO_IOMMU) {
- ret = iommu_group_claim_dma_owner(group->iommu_group, f.file);
- if (ret)
- goto unlock_out;
+ if (iommu_group_claim_dma_owner(group->iommu_group, f.file))
+ pr_warn("Failed to claim DMA owner");
}
driver = container->iommu_driver;
@@ -1021,7 +1021,8 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd)
group->iommu_group,
group->type);
if (ret) {
- if (group->type = VFIO_IOMMU)
+ if (group->type = VFIO_IOMMU &&
+ iommu_group_dma_owner_claimed(group->iommu_group))
iommu_group_release_dma_owner(
group->iommu_group);
goto unlock_out;
--
2.30.2
next reply other threads:[~2022-07-01 6:17 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-01 6:17 Alexey Kardashevskiy [this message]
2022-07-01 7:10 ` [RFC PATCH kernel] vfio: Skip checking for IOMMU_CAP_CACHE_COHERENCY on POWER and more Tian, Kevin
2022-07-05 0:49 ` Jason Gunthorpe
2022-07-07 1:06 ` Tian, Kevin
2022-07-01 10:34 ` Robin Murphy
2022-07-01 23:40 ` Tian, Kevin
2022-07-03 0:22 ` Jason Gunthorpe
2022-07-03 0:26 ` Jason Gunthorpe
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