Messages in this thread | | | Date | Sun, 21 May 2023 14:21:25 +0800 | Subject | Re: [PATCH v6 2/4] iommu: Move global PASID allocation from SVA to core | From | Baolu Lu <> |
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On 5/20/23 4:32 AM, Jacob Pan wrote: > Global PASID can be used beyond SVA. For example, drivers that use > Intel ENQCMD to submit work must use global PASIDs in that PASID > is stored in a per CPU MSR. When such device need to submit work > for in-kernel DMA with PASID, it must allocate PASIDs from the same > global number space to avoid conflict. > > This patch moves global PASID allocation APIs from SVA to IOMMU APIs. > Reserved PASIDs, currently only RID_PASID, are excluded from the global > PASID allocation. > > It is expected that device drivers will use the allocated PASIDs to > attach to appropriate IOMMU domains for use. > > Signed-off-by: Jacob Pan<jacob.jun.pan@linux.intel.com> > --- > v6: explicitly exclude reserved a range from SVA PASID allocation > check mm PASID compatibility with device > v5: move PASID range check inside API so that device drivers only pass > in struct device* (Kevin) > v4: move dummy functions outside ifdef CONFIG_IOMMU_SVA (Baolu) > --- > drivers/iommu/iommu-sva.c | 33 ++++++++++++++------------------- > drivers/iommu/iommu.c | 24 ++++++++++++++++++++++++ > include/linux/iommu.h | 10 ++++++++++ > 3 files changed, 48 insertions(+), 19 deletions(-) > > diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c > index 9821bc44f5ac..7fe8e977d8eb 100644 > --- a/drivers/iommu/iommu-sva.c > +++ b/drivers/iommu/iommu-sva.c > @@ -10,33 +10,33 @@ > #include "iommu-sva.h" > > static DEFINE_MUTEX(iommu_sva_lock); > -static DEFINE_IDA(iommu_global_pasid_ida); > > /* Allocate a PASID for the mm within range (inclusive) */ > -static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max) > +static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev) > { > + ioasid_t pasid; > int ret = 0; > > - if (min == IOMMU_PASID_INVALID || > - max == IOMMU_PASID_INVALID || > - min == 0 || max < min) > - return -EINVAL; > - > if (!arch_pgtable_dma_compat(mm)) > return -EBUSY; > > mutex_lock(&iommu_sva_lock); > /* Is a PASID already associated with this mm? */ > if (mm_valid_pasid(mm)) { > - if (mm->pasid < min || mm->pasid > max) > - ret = -EOVERFLOW; > + if (mm->pasid <= dev->iommu->max_pasids) > + goto out; > + dev_err(dev, "current mm PASID %d exceeds device range %d!", > + mm->pasid, dev->iommu->max_pasids); > + ret = -ERANGE; > goto out; > }
Nit: Above is just refactoring, so it's better to keep the code behavior consistent. For example, no need to change the error# from -EOVERFLOW to -ERANGE, and no need to leave a new kernel message.
Anyway, if you think these changes are helpful, it's better to have them in separated patches.
In the end, perhaps we can simply have code like this:
if (mm_valid_pasid(mm)) { if (mm->pasid > dev->iommu->max_pasids) ret = -EOVERFLOW; goto out; }
Others look good to me, with above addressed,
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Best regards, baolu
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