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 <[email protected]
<mailto:[email protected]>> 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 <[email protected]
<mailto:[email protected]>>
> > ---
> > 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 <[email protected]
<mailto:[email protected]>> 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 <[email protected]
<mailto:[email protected]>>
> > ---
> > 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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