[PATCH 3/5] iommu: Add return errno rules to ->attach_dev ops
From: Nicolin Chen <hidden>
Date: 2022-09-13 08:25:23
Also in:
linux-arm-msm, linux-iommu, linux-mediatek, linux-rockchip, linux-tegra, lkml
Subsystem:
iommu subsystem, the rest · Maintainers:
Joerg Roedel, Will Deacon, Linus Torvalds
Cases like VFIO wish to attach a device to an existing domain that was not allocated specifically from the device. This raises a condition where the IOMMU driver can fail the domain attach because the domain and device are incompatible with each other. This is a soft failure that can be resolved by using a different domain. Provide a dedicated errno EINVAL from the IOMMU driver during attach that the reason attached failed is because of domain incompatability. VFIO can use this to know attach is a soft failure and it should continue searching. Otherwise the attach will be a hard failure and VFIO will return the code to userspace. Update kdocs first to add rules of return errno to ->attach_dev ops. Suggested-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Nicolin Chen <redacted> --- include/linux/iommu.h | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index ea30f00dc145..c5d7ec0187c7 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h@@ -266,6 +266,17 @@ struct iommu_ops { /** * struct iommu_domain_ops - domain specific operations * @attach_dev: attach an iommu domain to a device + * Rules of its return errno: + * EINVAL - Exclusively, device and domain are incompatible. Must + * avoid kernel prints along with this errno. Any EINVAL + * returned from kAPIs must be converted to ENODEV if it + * is device-specific, or to some other reasonable errno + * being listed below + * ENOMEM - Out of memory + * ENOSPC - No space left on device + * EBUSY - Device is attached to a domain and cannot be changed + * ENODEV - Device specific errors, not able to be attached + * <others> - Treated as ENODEV by the caller. Use is discouraged * @detach_dev: detach an iommu domain from a device * @map: map a physically contiguous memory region to an iommu domain * @map_pages: map a physically contiguous set of pages of the same size to
--
2.17.1
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