Messages in this thread | | | Date | Tue, 27 Jun 2023 16:21:56 +0800 | Subject | Re: [PATCH 1/2] iommu: Prevent RESV_DIRECT devices from blocking domains | From | Baolu Lu <> |
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On 2023/6/27 16:15, Tian, Kevin wrote: >> From: Baolu Lu<baolu.lu@linux.intel.com> >> Sent: Tuesday, June 27, 2023 4:01 PM >> >> On 2023/6/27 15:54, Tian, Kevin wrote: >>>> From: Baolu Lu<baolu.lu@linux.intel.com> >>>> Sent: Tuesday, June 13, 2023 11:15 AM >>>> >>>> On 6/12/23 4:28 PM, Liu, Jingqi wrote: >>>>> On 6/7/2023 11:51 AM, Lu Baolu wrote: >>>>>> - >>>>>> - BUG_ON(!domain->pgsize_bitmap); >>>>>> - >>>>>> - pg_size = 1UL << __ffs(domain->pgsize_bitmap); >>>>>> + pg_size = domain->pgsize_bitmap ? 1UL << >>>>>> __ffs(domain->pgsize_bitmap) : 0; >>>>> Would it be better to add the following check here? >>>>> if (WARN_ON(!pg_size)) >>>>> return -EINVAL; >>>>> >>>>> Instead of checking latter in the loop as follows. >>>>> if (WARN_ON_ONCE(!pg_size)) { >>>>> ret = -EINVAL; >>>>> goto out; >>>>> } >>>> I am afraid no. Only the paging domains need a valid pg_size. That's the >>>> reason why I put it after the iommu_is_dma_domain() check. The >> previous >>>> code has the same behavior too. >>>> >>> You could also add the dma domain check here. pg_size is static >>> then it makes more sense to verify it once instead of in a loop. >> Agreed. Does below additional change make sense? >> >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >> index e59de7852067..3be88b5f36bb 100644 >> --- a/drivers/iommu/iommu.c >> +++ b/drivers/iommu/iommu.c >> @@ -962,6 +962,9 @@ static int >> iommu_create_device_direct_mappings(struct iommu_domain *domain, >> pg_size = domain->pgsize_bitmap ? 1UL << >> __ffs(domain->pgsize_bitmap) : 0; >> INIT_LIST_HEAD(&mappings); >> >> + if (WARN_ON_ONCE((domain->type & __IOMMU_DOMAIN_PAGING) >> && >> !pg_size)) >> + return -EINVAL; > what's the reason of not using iommu_is_dma_domain()? this is called > in the probe path only for the default domain. Otherwise if you change > like this then you also want to change the check in the loop later to be > consistent. >
Yes. iommu_is_dma_domain() is better.
Best regards, baolu
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