| Message ID | 1411163922-8833-1-git-send-email-mitchelh@codeaurora.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Mitchel, I have made changes to the arm smmu driver paging support, as a part of the huge page support patch. Will is currently reviewing changes made by me. I should be able to post my patch in the next couple of weeks. Regards Vaun > -----Original Message----- > From: iommu-bounces@lists.linux-foundation.org [mailto:iommu- > bounces@lists.linux-foundation.org] On Behalf Of Mitchel Humpherys > Sent: Saturday, September 20, 2014 3:29 AM > To: linux-arm-kernel@lists.infradead.org; iommu@lists.linux-foundation.org; > Will Deacon > Subject: [PATCH] iommu/arm-smmu: fix bug in pmd construction > > We are using the same pfn for every pte we create while constructing the pmd. > Fix this by actually updating the pfn on each iteration of the pmd construction > loop. > > It's not clear if we can actually hit this bug right now since iommu_map splits up > the calls to .map based on the page size, so we only ever seem to iterate this > loop once. However, things might change in the future that might cause us to > hit this. > > Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org> > --- > Will, I was unable to come up with a test case to hit this bug based on what I > said in the commit message above. Not sure if my analysis is completely off > base, my head is still spinning from all these page tables :). > --- > drivers/iommu/arm-smmu.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index > ca18d6d42a..eba4cb390c 100644 > --- a/drivers/iommu/arm-smmu.c > +++ b/drivers/iommu/arm-smmu.c > @@ -1368,6 +1368,7 @@ static int arm_smmu_alloc_init_pmd(struct > arm_smmu_device *smmu, pud_t *pud, > ret = arm_smmu_alloc_init_pte(smmu, pmd, addr, next, pfn, > prot, stage); > phys += next - addr; > + pfn = __phys_to_pfn(phys); > } while (pmd++, addr = next, addr < end); > > return ret; > -- > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > hosted by The Linux Foundation > > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu
On Sun, Sep 21, 2014 at 08:56:28AM +0100, Varun Sethi wrote: > I have made changes to the arm smmu driver paging support, as a part of > the huge page support patch. Will is currently reviewing changes made by > me. I should be able to post my patch in the next couple of weeks. Yup, but this patch looks like a sensible change for now. I agree that we can't currently hit the bug, but that code is intended to be usable for use across multiple PMDs, so I'll apply this. Will
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index ca18d6d42a..eba4cb390c 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c @@ -1368,6 +1368,7 @@ static int arm_smmu_alloc_init_pmd(struct arm_smmu_device *smmu, pud_t *pud, ret = arm_smmu_alloc_init_pte(smmu, pmd, addr, next, pfn, prot, stage); phys += next - addr; + pfn = __phys_to_pfn(phys); } while (pmd++, addr = next, addr < end); return ret;
We are using the same pfn for every pte we create while constructing the pmd. Fix this by actually updating the pfn on each iteration of the pmd construction loop. It's not clear if we can actually hit this bug right now since iommu_map splits up the calls to .map based on the page size, so we only ever seem to iterate this loop once. However, things might change in the future that might cause us to hit this. Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org> --- Will, I was unable to come up with a test case to hit this bug based on what I said in the commit message above. Not sure if my analysis is completely off base, my head is still spinning from all these page tables :). --- drivers/iommu/arm-smmu.c | 1 + 1 file changed, 1 insertion(+)