On 2023/11/21 13:19, Nicolin Chen wrote:
On Tue, Nov 21, 2023 at 01:02:49PM +0800, Baolu Lu wrote:
On 11/17/23 9:07 PM, Yi Liu wrote:
In nested translation, the stage-1 page table is user-managed but cached by the IOMMU hardware, so an update on present page table entries in the stage-1 page table should be followed with a cache invalidation.
Add an IOMMU_HWPT_INVALIDATE ioctl to support such a cache invalidation. It takes hwpt_id to specify the iommu_domain, and a multi-entry array to support multiple invalidation requests in one ioctl.
Check cache_invalidate_user op in the iommufd_hw_pagetable_alloc_nested, since all nested domains need that.
Co-developed-by: Nicolin Chennicolinc@nvidia.com Signed-off-by: Nicolin Chennicolinc@nvidia.com Signed-off-by: Yi Liuyi.l.liu@intel.com
drivers/iommu/iommufd/hw_pagetable.c | 35 +++++++++++++++++++++++++ drivers/iommu/iommufd/iommufd_private.h | 9 +++++++ drivers/iommu/iommufd/main.c | 3 +++ include/uapi/linux/iommufd.h | 35 +++++++++++++++++++++++++ 4 files changed, 82 insertions(+)
diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c index 2abbeafdbd22..367459d92f69 100644 --- a/drivers/iommu/iommufd/hw_pagetable.c +++ b/drivers/iommu/iommufd/hw_pagetable.c @@ -238,6 +238,11 @@ iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx, rc = -EINVAL; goto out_abort; }
/* Driver is buggy by missing cache_invalidate_user in domain_ops */if (WARN_ON_ONCE(!hwpt->domain->ops->cache_invalidate_user)) {rc = -EINVAL;goto out_abort;} return hwpt_nested;The WARN message here may cause kernel regression when users bisect issues. Till this patch, there are no drivers support the cache_invalidation_user callback yet.
Ah, this is an unintended consequence from our uAPI bisect to merge the nesting alloc first...
Would removing the WARN_ON_ONCE be okay? Although having this WARN is actually the point here...
seems like we may need to remove it. how about your opinion, @Jason?
Thanks Nic