Messages in this thread | | | Date | Tue, 28 Nov 2023 13:54:45 +0800 | Subject | Re: [PATCH v6 2/6] iommufd: Add IOMMU_HWPT_INVALIDATE | From | Yi Liu <> |
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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 Chen<nicolinc@nvidia.com> >>> Signed-off-by: Nicolin Chen<nicolinc@nvidia.com> >>> Signed-off-by: Yi Liu<yi.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
-- Regards, Yi Liu
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