| Message ID | 20191023195515.13168-3-rcampbell@nvidia.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Jason Gunthorpe |
| Headers | show |
| Series | HMM tests and minor fixes | expand |
On Wed, Oct 23, 2019 at 12:55:14PM -0700, Ralph Campbell wrote: > If a device driver like nouveau tries to use hmm_range_fault() to access > the special shared zero page in system memory, hmm_range_fault() will > return -EFAULT and kill the process. > Allow hmm_range_fault() to return success (0) when the CPU pagetable > entry points to the special shared zero page. > page_to_pfn() and pfn_to_page() are defined on the zero page so just > handle it like any other page. > > Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> > Cc: Christoph Hellwig <hch@lst.de> Reviewed-by: "Jérôme Glisse" <jglisse@redhat.com> > Cc: Jason Gunthorpe <jgg@mellanox.com> > --- > mm/hmm.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/mm/hmm.c b/mm/hmm.c > index acf7a664b38c..8c96c9ddcae5 100644 > --- a/mm/hmm.c > +++ b/mm/hmm.c > @@ -529,8 +529,14 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, > if (unlikely(!hmm_vma_walk->pgmap)) > return -EBUSY; > } else if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pte_special(pte)) { > - *pfn = range->values[HMM_PFN_SPECIAL]; > - return -EFAULT; > + if (!is_zero_pfn(pte_pfn(pte))) { > + *pfn = range->values[HMM_PFN_SPECIAL]; > + return -EFAULT; > + } > + /* > + * Since each architecture defines a struct page for the zero > + * page, just fall through and treat it like a normal page. > + */ > } > > *pfn = hmm_device_entry_from_pfn(range, pte_pfn(pte)) | cpu_flags; > -- > 2.20.1 >
On 23.10.19 21:55, Ralph Campbell wrote: > If a device driver like nouveau tries to use hmm_range_fault() to access > the special shared zero page in system memory, hmm_range_fault() will > return -EFAULT and kill the process. > Allow hmm_range_fault() to return success (0) when the CPU pagetable > entry points to the special shared zero page. > page_to_pfn() and pfn_to_page() are defined on the zero page so just > handle it like any other page. > > Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> > Cc: Christoph Hellwig <hch@lst.de> > Cc: "Jérôme Glisse" <jglisse@redhat.com> > Cc: Jason Gunthorpe <jgg@mellanox.com> > --- > mm/hmm.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/mm/hmm.c b/mm/hmm.c > index acf7a664b38c..8c96c9ddcae5 100644 > --- a/mm/hmm.c > +++ b/mm/hmm.c > @@ -529,8 +529,14 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, > if (unlikely(!hmm_vma_walk->pgmap)) > return -EBUSY; > } else if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pte_special(pte)) { > - *pfn = range->values[HMM_PFN_SPECIAL]; > - return -EFAULT; > + if (!is_zero_pfn(pte_pfn(pte))) { > + *pfn = range->values[HMM_PFN_SPECIAL]; > + return -EFAULT; > + } > + /* > + * Since each architecture defines a struct page for the zero > + * page, just fall through and treat it like a normal page. > + */ > } > > *pfn = hmm_device_entry_from_pfn(range, pte_pfn(pte)) | cpu_flags; > Acked-by: David Hildenbrand <david@redhat.com>
On Wed, Oct 23, 2019 at 12:55:14PM -0700, Ralph Campbell wrote: > If a device driver like nouveau tries to use hmm_range_fault() to access > the special shared zero page in system memory, hmm_range_fault() will > return -EFAULT and kill the process. > Allow hmm_range_fault() to return success (0) when the CPU pagetable > entry points to the special shared zero page. > page_to_pfn() and pfn_to_page() are defined on the zero page so just > handle it like any other page. > > Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> > Cc: Christoph Hellwig <hch@lst.de> > Cc: "Jérôme Glisse" <jglisse@redhat.com> > Cc: Jason Gunthorpe <jgg@mellanox.com> > --- > mm/hmm.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) Applied to hmm.git Thanks, Jason
diff --git a/mm/hmm.c b/mm/hmm.c index acf7a664b38c..8c96c9ddcae5 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -529,8 +529,14 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, if (unlikely(!hmm_vma_walk->pgmap)) return -EBUSY; } else if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pte_special(pte)) { - *pfn = range->values[HMM_PFN_SPECIAL]; - return -EFAULT; + if (!is_zero_pfn(pte_pfn(pte))) { + *pfn = range->values[HMM_PFN_SPECIAL]; + return -EFAULT; + } + /* + * Since each architecture defines a struct page for the zero + * page, just fall through and treat it like a normal page. + */ } *pfn = hmm_device_entry_from_pfn(range, pte_pfn(pte)) | cpu_flags;
If a device driver like nouveau tries to use hmm_range_fault() to access the special shared zero page in system memory, hmm_range_fault() will return -EFAULT and kill the process. Allow hmm_range_fault() to return success (0) when the CPU pagetable entry points to the special shared zero page. page_to_pfn() and pfn_to_page() are defined on the zero page so just handle it like any other page. Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Cc: Christoph Hellwig <hch@lst.de> Cc: "Jérôme Glisse" <jglisse@redhat.com> Cc: Jason Gunthorpe <jgg@mellanox.com> --- mm/hmm.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)