Messages in this thread Patch in this message | | | Date | Tue, 30 Aug 2022 09:46:01 +0800 | Subject | Re: [PATCH v12 07/17] iommu: Try to allocate blocking domain when probing device | From | Baolu Lu <> |
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On 2022/8/30 01:27, Jason Gunthorpe wrote: > On Mon, Aug 29, 2022 at 11:40:24AM +0800, Baolu Lu wrote: >> On 2022/8/26 22:52, Jason Gunthorpe wrote: >>> On Fri, Aug 26, 2022 at 08:11:31PM +0800, Lu Baolu wrote: >>>> Allocate the blocking domain when probing devices if the driver supports >>>> blocking domain allocation. Otherwise, revert to the previous behavior, >>>> that is, use UNMANAGED domain instead when the blocking domain is needed. >>>> >>>> Signed-off-by: Lu Baolu<baolu.lu@linux.intel.com> >>>> Tested-by: Zhangfei Gao<zhangfei.gao@linaro.org> >>>> Tested-by: Tony Zhu<tony.zhu@intel.com> >>>> --- >>>> drivers/iommu/iommu.c | 29 +++++++++++++++++------------ >>>> 1 file changed, 17 insertions(+), 12 deletions(-) >>> This seems like a lot of overhead to allocate these things for every >>> group? >>> >>> Why not add a simple refcount on the blocking domain instead and >>> allocate the domain on the pasid attach like we do for ownership? >> >> I am working towards implementing static instance of blocking domain for >> each IOMMU driver, and then, there's no much overhead to allocate it in >> the probing device path. > > Well, I thought about that and I don't think we can get > there in a short order.
Yes. Fair enough.
> Would rather you progress this series without > getting entangled in such a big adventure
Agreed. I will drop this patch and add below code in the iommu interface:
--- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -3219,6 +3219,26 @@ int iommu_attach_device_pasid(struct iommu_domain *domain, return -ENODEV;
mutex_lock(&group->mutex); + + /* + * The underlying IOMMU driver needs to support blocking domain + * allocation and the callback to block DMA transactions with a + * specific PASID. + */ + if (!group->blocking_domain) { + group->blocking_domain = __iommu_domain_alloc(dev->bus, + IOMMU_DOMAIN_BLOCKED); + if (!group->blocking_domain) { + ret = -ENODEV; + goto out_unlock; + } + } + + if (!group->blocking_domain->ops->set_dev_pasid) { + ret = -EOPNOTSUPP; + goto out_unlock; + } + curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain, GFP_KERNEL); if (curr) { ret = xa_err(curr) ? : -EBUSY; Currently both ARM SMMUv3 and VT-d drivers use static blocking domain. Hence I didn't use a refcount for blocking domain release here.
Best regards, baolu
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