Messages in this thread | | | Subject | Re: [PATCH] iommu/vt-d: Fix a bug in intel_iommu_iova_to_phys() for huge page | From | Lu Baolu <> | Date | Thu, 20 Feb 2020 07:32:54 +0800 |
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Hi,
On 2020/2/20 2:51, Yonghyun Hwang wrote: > Hello Lu and Moritz, > > I think it's better to keep "if (level > 1)" because > level_to_offset_bits() returns (unsigned int) -1 * LEVEL_STRIDE if level > becomes 0.
@level will never be 0 in this case.
Best regards, baolu
> > static inline unsigned int level_to_offset_bits(int level) > { > return (level - 1) * LEVEL_STRIDE; > } > > On Tue, Feb 18, 2020 at 8:42 PM Moritz Fischer <mdf@kernel.org > <mailto:mdf@kernel.org>> wrote: > > Hi Baolu, Yonghyun > > On Wed, Feb 19, 2020 at 11:15:36AM +0800, Lu Baolu wrote: > > Hi Yonghyun, > > > > Thanks for the patch. > > > > On 2020/2/19 6:23, Yonghyun Hwang wrote: > > > intel_iommu_iova_to_phys() has a bug when it translates an IOVA > for a huge > > > page onto its corresponding physical address. This commit fixes > the bug by > > > accomodating the level of page entry for the IOVA and adds > IOVA's lower > > > address to the physical address. > > > > Signed-off-by: Yonghyun Hwang <yonghyun@google.com > <mailto:yonghyun@google.com>> > > > --- > > > drivers/iommu/intel-iommu.c | 11 +++++++++-- > > > 1 file changed, 9 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/iommu/intel-iommu.c > b/drivers/iommu/intel-iommu.c > > > index 0c8d81f56a30..ed6e69adb578 100644 > > > --- a/drivers/iommu/intel-iommu.c > > > +++ b/drivers/iommu/intel-iommu.c > > > @@ -5555,13 +5555,20 @@ static phys_addr_t > intel_iommu_iova_to_phys(struct iommu_domain *domain, > > > struct dma_pte *pte; > > > int level = 0; > > > u64 phys = 0; > > > + const unsigned long pfn = iova >> VTD_PAGE_SHIFT; > > > > Why do you need a "const unsigned long" here? > > > > It's because pfn_to_dma_pte() takes pfn for its second parameter as > "unsigned int" type and pfn is not changed in intel_iommu_iova_to_phys(). > > > > > > if (dmar_domain->flags & DOMAIN_FLAG_LOSE_CHILDREN) > > > return 0; > > > - pte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, > &level); > > > - if (pte) > > > + pte = pfn_to_dma_pte(dmar_domain, pfn, &level); > > > + if (pte) { > > > phys = dma_pte_addr(pte); > > > + if (level > 1) > > > + phys += (pfn & > > > + ((1UL << > level_to_offset_bits(level)) - 1)) > > > + << VTD_PAGE_SHIFT; > > > + phys += iova & (VTD_PAGE_SIZE - 1); > > > > How about > > > > > diff --git a/drivers/iommu/intel-iommu.c > b/drivers/iommu/intel-iommu.c > > index 9dc37672bf89..bd17c2510bb2 100644 > > --- a/drivers/iommu/intel-iommu.c > > +++ b/drivers/iommu/intel-iommu.c > > @@ -5693,8 +5693,14 @@ static phys_addr_t > intel_iommu_iova_to_phys(struct > > iommu_domain *domain, > > u64 phys = 0; > > > > pte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, > &level); > > - if (pte) > > + if (pte) { > > + unsigned long offset_mask; > > + > > + offset_mask = BIT_MASK(level_to_offset_bits(level) + > > + VTD_PAGE_SHIFT) - 1; > > phys = dma_pte_addr(pte); > > + phys += iova & (bitmask - 1); > Did you mean: > > phys += iova & (offset_mask - 1); > > > + } > > At that point why not define a helper: > > static inline unsigned long offset_mask(int level) > { > return BIT_MASK(level_to_offset_bits(level) + > VTD_PAGE_SHIFT) - 1; > } > > At which point the above would reduce to: > > if (pte) > phys = dma_pte_addr(pte) + iova & offset_mask(level) - 1; > > > > Let me introduce the helper function and upstream the patch again. Thank > you Lu and Moritz. > > > I might've fatfingered something here, but you get the idea :) > > Cheers, > Moritz > > > On Tue, Feb 18, 2020 at 8:42 PM Moritz Fischer <mdf@kernel.org > <mailto:mdf@kernel.org>> wrote: > > Hi Baolu, Yonghyun > > On Wed, Feb 19, 2020 at 11:15:36AM +0800, Lu Baolu wrote: > > Hi Yonghyun, > > > > Thanks for the patch. > > > > On 2020/2/19 6:23, Yonghyun Hwang wrote: > > > intel_iommu_iova_to_phys() has a bug when it translates an IOVA > for a huge > > > page onto its corresponding physical address. This commit fixes > the bug by > > > accomodating the level of page entry for the IOVA and adds > IOVA's lower > > > address to the physical address. > > > > Signed-off-by: Yonghyun Hwang <yonghyun@google.com > <mailto:yonghyun@google.com>> > > > --- > > > drivers/iommu/intel-iommu.c | 11 +++++++++-- > > > 1 file changed, 9 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/iommu/intel-iommu.c > b/drivers/iommu/intel-iommu.c > > > index 0c8d81f56a30..ed6e69adb578 100644 > > > --- a/drivers/iommu/intel-iommu.c > > > +++ b/drivers/iommu/intel-iommu.c > > > @@ -5555,13 +5555,20 @@ static phys_addr_t > intel_iommu_iova_to_phys(struct iommu_domain *domain, > > > struct dma_pte *pte; > > > int level = 0; > > > u64 phys = 0; > > > + const unsigned long pfn = iova >> VTD_PAGE_SHIFT; > > > > Why do you need a "const unsigned long" here? > > > > > if (dmar_domain->flags & DOMAIN_FLAG_LOSE_CHILDREN) > > > return 0; > > > - pte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, > &level); > > > - if (pte) > > > + pte = pfn_to_dma_pte(dmar_domain, pfn, &level); > > > + if (pte) { > > > phys = dma_pte_addr(pte); > > > + if (level > 1) > > > + phys += (pfn & > > > + ((1UL << > level_to_offset_bits(level)) - 1)) > > > + << VTD_PAGE_SHIFT; > > > + phys += iova & (VTD_PAGE_SIZE - 1); > > > > How about > > > > > diff --git a/drivers/iommu/intel-iommu.c > b/drivers/iommu/intel-iommu.c > > index 9dc37672bf89..bd17c2510bb2 100644 > > --- a/drivers/iommu/intel-iommu.c > > +++ b/drivers/iommu/intel-iommu.c > > @@ -5693,8 +5693,14 @@ static phys_addr_t > intel_iommu_iova_to_phys(struct > > iommu_domain *domain, > > u64 phys = 0; > > > > pte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, > &level); > > - if (pte) > > + if (pte) { > > + unsigned long offset_mask; > > + > > + offset_mask = BIT_MASK(level_to_offset_bits(level) + > > + VTD_PAGE_SHIFT) - 1; > > phys = dma_pte_addr(pte); > > + phys += iova & (bitmask - 1); > Did you mean: > > phys += iova & (offset_mask - 1); > > > + } > > At that point why not define a helper: > > static inline unsigned long offset_mask(int level) > { > return BIT_MASK(level_to_offset_bits(level) + > VTD_PAGE_SHIFT) - 1; > } > > At which point the above would reduce to: > > if (pte) > phys = dma_pte_addr(pte) + iova & offset_mask(level) - 1; > > I might've fatfingered something here, but you get the idea :) > > Cheers, > Moritz >
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