| Message ID | 20211104012001.2555676-1-apopple@nvidia.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/hmm.c: Allow VM_MIXEDMAP to work with hmm_range_fault | expand |
On Thu, Nov 04, 2021 at 12:20:01PM +1100, Alistair Popple wrote: > hmm_range_fault() can be used instead of get_user_pages() for devices > which allow faulting however unlike get_user_pages() it will return an > error when used on a VM_MIXEDMAP range. > > To make hmm_range_fault() more closely match get_user_pages() remove > this restriction. This requires dealing with the !ARCH_HAS_PTE_SPECIAL > case in hmm_vma_handle_pte(). Rather than replicating the logic of > vm_normal_page() call it directly and do a check for the zero pfn > similar to what get_user_pages() currently does. > > Also add a test to hmm selftest to verify functionality. Please add a fixes line > Signed-off-by: Alistair Popple <apopple@nvidia.com> > --- > lib/test_hmm.c | 24 +++++++++++++++ > mm/hmm.c | 5 +-- > tools/testing/selftests/vm/hmm-tests.c | 42 ++++++++++++++++++++++++++ > 3 files changed, 69 insertions(+), 2 deletions(-) Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Jason
On Friday, 5 November 2021 11:25:57 PM AEDT Jason Gunthorpe wrote: > On Thu, Nov 04, 2021 at 12:20:01PM +1100, Alistair Popple wrote: > > hmm_range_fault() can be used instead of get_user_pages() for devices > > which allow faulting however unlike get_user_pages() it will return an > > error when used on a VM_MIXEDMAP range. > > > > To make hmm_range_fault() more closely match get_user_pages() remove > > this restriction. This requires dealing with the !ARCH_HAS_PTE_SPECIAL > > case in hmm_vma_handle_pte(). Rather than replicating the logic of > > vm_normal_page() call it directly and do a check for the zero pfn > > similar to what get_user_pages() currently does. > > > > Also add a test to hmm selftest to verify functionality. > > Please add a fixes line This has been the case since hmm_vma_get_pfns() was first introduced. Therefore the fixes line is: Fixes: da4c3c735ea4 ("mm/hmm/mirror: helper to snapshot CPU page table") Should I send a v2 adding that tag or does Andrew normally pick these up along with the Reviewed-by? Thanks. > > Signed-off-by: Alistair Popple <apopple@nvidia.com> > > --- > > lib/test_hmm.c | 24 +++++++++++++++ > > mm/hmm.c | 5 +-- > > tools/testing/selftests/vm/hmm-tests.c | 42 ++++++++++++++++++++++++++ > > 3 files changed, 69 insertions(+), 2 deletions(-) > > Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> > > Jason >
On Mon, 8 Nov 2021 18:58:01 +1100 Alistair Popple <apopple@nvidia.com> wrote: > On Friday, 5 November 2021 11:25:57 PM AEDT Jason Gunthorpe wrote: > > On Thu, Nov 04, 2021 at 12:20:01PM +1100, Alistair Popple wrote: > > > hmm_range_fault() can be used instead of get_user_pages() for devices > > > which allow faulting however unlike get_user_pages() it will return an > > > error when used on a VM_MIXEDMAP range. > > > > > > To make hmm_range_fault() more closely match get_user_pages() remove > > > this restriction. This requires dealing with the !ARCH_HAS_PTE_SPECIAL > > > case in hmm_vma_handle_pte(). Rather than replicating the logic of > > > vm_normal_page() call it directly and do a check for the zero pfn > > > similar to what get_user_pages() currently does. > > > > > > Also add a test to hmm selftest to verify functionality. > > > > Please add a fixes line > > This has been the case since hmm_vma_get_pfns() was first introduced. Therefore > the fixes line is: > > Fixes: da4c3c735ea4 ("mm/hmm/mirror: helper to snapshot CPU page table") > > Should I send a v2 adding that tag or does Andrew normally pick these up along > with the Reviewed-by? I got it. It needed a bit of rework due to the newly-added !pte_devmap() change in hmm_vma_handle_pte(). Please check carefully? From: Alistair Popple <apopple@nvidia.com> Subject: mm/hmm.c: Allow VM_MIXEDMAP to work with hmm_range_fault hmm_range_fault() can be used instead of get_user_pages() for devices which allow faulting however unlike get_user_pages() it will return an error when used on a VM_MIXEDMAP range. To make hmm_range_fault() more closely match get_user_pages() remove this restriction. This requires dealing with the !ARCH_HAS_PTE_SPECIAL case in hmm_vma_handle_pte(). Rather than replicating the logic of vm_normal_page() call it directly and do a check for the zero pfn similar to what get_user_pages() currently does. Also add a test to hmm selftest to verify functionality. Link: https://lkml.kernel.org/r/20211104012001.2555676-1-apopple@nvidia.com Fixes: da4c3c735ea4 ("mm/hmm/mirror: helper to snapshot CPU page table") Signed-off-by: Alistair Popple <apopple@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- lib/test_hmm.c | 24 +++++++++++++ mm/hmm.c | 5 +- tools/testing/selftests/vm/hmm-tests.c | 42 +++++++++++++++++++++++ 3 files changed, 69 insertions(+), 2 deletions(-) --- a/lib/test_hmm.c~mm-hmmc-allow-vm_mixedmap-to-work-with-hmm_range_fault +++ a/lib/test_hmm.c @@ -1086,9 +1086,33 @@ static long dmirror_fops_unlocked_ioctl( return 0; } +static int dmirror_fops_mmap(struct file *file, struct vm_area_struct *vma) +{ + unsigned long addr; + + for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) { + struct page *page; + int ret; + + page = alloc_page(GFP_KERNEL | __GFP_ZERO); + if (!page) + return -ENOMEM; + + ret = vm_insert_page(vma, addr, page); + if (ret) { + __free_page(page); + return ret; + } + put_page(page); + } + + return 0; +} + static const struct file_operations dmirror_fops = { .open = dmirror_fops_open, .release = dmirror_fops_release, + .mmap = dmirror_fops_mmap, .unlocked_ioctl = dmirror_fops_unlocked_ioctl, .llseek = default_llseek, .owner = THIS_MODULE, --- a/mm/hmm.c~mm-hmmc-allow-vm_mixedmap-to-work-with-hmm_range_fault +++ a/mm/hmm.c @@ -300,7 +300,8 @@ static int hmm_vma_handle_pte(struct mm_ * Since each architecture defines a struct page for the zero page, just * fall through and treat it like a normal page. */ - if (pte_special(pte) && !pte_devmap(pte) && + if (!vm_normal_page(walk->vma, addr, pte) && + !pte_devmap(pte) && !is_zero_pfn(pte_pfn(pte))) { if (hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0)) { pte_unmap(ptep); @@ -518,7 +519,7 @@ static int hmm_vma_walk_test(unsigned lo struct hmm_range *range = hmm_vma_walk->range; struct vm_area_struct *vma = walk->vma; - if (!(vma->vm_flags & (VM_IO | VM_PFNMAP | VM_MIXEDMAP)) && + if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)) && vma->vm_flags & VM_READ) return 0; --- a/tools/testing/selftests/vm/hmm-tests.c~mm-hmmc-allow-vm_mixedmap-to-work-with-hmm_range_fault +++ a/tools/testing/selftests/vm/hmm-tests.c @@ -1251,6 +1251,48 @@ TEST_F(hmm, anon_teardown) /* * Test memory snapshot without faulting in pages accessed by the device. */ +TEST_F(hmm, mixedmap) +{ + struct hmm_buffer *buffer; + unsigned long npages; + unsigned long size; + unsigned char *m; + int ret; + + npages = 1; + size = npages << self->page_shift; + + buffer = malloc(sizeof(*buffer)); + ASSERT_NE(buffer, NULL); + + buffer->fd = -1; + buffer->size = size; + buffer->mirror = malloc(npages); + ASSERT_NE(buffer->mirror, NULL); + + + /* Reserve a range of addresses. */ + buffer->ptr = mmap(NULL, size, + PROT_READ | PROT_WRITE, + MAP_PRIVATE, + self->fd, 0); + ASSERT_NE(buffer->ptr, MAP_FAILED); + + /* Simulate a device snapshotting CPU pagetables. */ + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages); + ASSERT_EQ(ret, 0); + ASSERT_EQ(buffer->cpages, npages); + + /* Check what the device saw. */ + m = buffer->mirror; + ASSERT_EQ(m[0], HMM_DMIRROR_PROT_READ); + + hmm_buffer_free(buffer); +} + +/* + * Test memory snapshot without faulting in pages accessed by the device. + */ TEST_F(hmm2, snapshot) { struct hmm_buffer *buffer;
On Tuesday, 16 November 2021 3:48:42 PM AEDT Andrew Morton wrote: > On Mon, 8 Nov 2021 18:58:01 +1100 Alistair Popple <apopple@nvidia.com> wrote: > > > On Friday, 5 November 2021 11:25:57 PM AEDT Jason Gunthorpe wrote: > > > On Thu, Nov 04, 2021 at 12:20:01PM +1100, Alistair Popple wrote: > > > > hmm_range_fault() can be used instead of get_user_pages() for devices > > > > which allow faulting however unlike get_user_pages() it will return an > > > > error when used on a VM_MIXEDMAP range. > > > > > > > > To make hmm_range_fault() more closely match get_user_pages() remove > > > > this restriction. This requires dealing with the !ARCH_HAS_PTE_SPECIAL > > > > case in hmm_vma_handle_pte(). Rather than replicating the logic of > > > > vm_normal_page() call it directly and do a check for the zero pfn > > > > similar to what get_user_pages() currently does. > > > > > > > > Also add a test to hmm selftest to verify functionality. > > > > > > Please add a fixes line > > > > This has been the case since hmm_vma_get_pfns() was first introduced. Therefore > > the fixes line is: > > > > Fixes: da4c3c735ea4 ("mm/hmm/mirror: helper to snapshot CPU page table") > > > > Should I send a v2 adding that tag or does Andrew normally pick these up along > > with the Reviewed-by? > > I got it. > > It needed a bit of rework due to the newly-added !pte_devmap() change > in hmm_vma_handle_pte(). Please check carefully? Thanks. The rework looks good to me - changing pte_special() to vm_insert_page() does not change the logic of the !pte_devmap() change. In either case the value of pte_special() or vm_insert_page() is ignored when pte_devmap()==True as intended by the !pte_devmap() change. For good measure I rerun the HMM selftest as well. > From: Alistair Popple <apopple@nvidia.com> > Subject: mm/hmm.c: Allow VM_MIXEDMAP to work with hmm_range_fault > > hmm_range_fault() can be used instead of get_user_pages() for devices > which allow faulting however unlike get_user_pages() it will return an > error when used on a VM_MIXEDMAP range. > > To make hmm_range_fault() more closely match get_user_pages() remove > this restriction. This requires dealing with the !ARCH_HAS_PTE_SPECIAL > case in hmm_vma_handle_pte(). Rather than replicating the logic of > vm_normal_page() call it directly and do a check for the zero pfn > similar to what get_user_pages() currently does. > > Also add a test to hmm selftest to verify functionality. > > Link: https://lkml.kernel.org/r/20211104012001.2555676-1-apopple@nvidia.com > Fixes: da4c3c735ea4 ("mm/hmm/mirror: helper to snapshot CPU page table") > Signed-off-by: Alistair Popple <apopple@nvidia.com> > Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> > Cc: Jerome Glisse <jglisse@redhat.com> > Cc: John Hubbard <jhubbard@nvidia.com> > Cc: Zi Yan <ziy@nvidia.com> > Cc: Ralph Campbell <rcampbell@nvidia.com> > Cc: Felix Kuehling <Felix.Kuehling@amd.com> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > --- > > lib/test_hmm.c | 24 +++++++++++++ > mm/hmm.c | 5 +- > tools/testing/selftests/vm/hmm-tests.c | 42 +++++++++++++++++++++++ > 3 files changed, 69 insertions(+), 2 deletions(-) > > --- a/lib/test_hmm.c~mm-hmmc-allow-vm_mixedmap-to-work-with-hmm_range_fault > +++ a/lib/test_hmm.c > @@ -1086,9 +1086,33 @@ static long dmirror_fops_unlocked_ioctl( > return 0; > } > > +static int dmirror_fops_mmap(struct file *file, struct vm_area_struct *vma) > +{ > + unsigned long addr; > + > + for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) { > + struct page *page; > + int ret; > + > + page = alloc_page(GFP_KERNEL | __GFP_ZERO); > + if (!page) > + return -ENOMEM; > + > + ret = vm_insert_page(vma, addr, page); > + if (ret) { > + __free_page(page); > + return ret; > + } > + put_page(page); > + } > + > + return 0; > +} > + > static const struct file_operations dmirror_fops = { > .open = dmirror_fops_open, > .release = dmirror_fops_release, > + .mmap = dmirror_fops_mmap, > .unlocked_ioctl = dmirror_fops_unlocked_ioctl, > .llseek = default_llseek, > .owner = THIS_MODULE, > --- a/mm/hmm.c~mm-hmmc-allow-vm_mixedmap-to-work-with-hmm_range_fault > +++ a/mm/hmm.c > @@ -300,7 +300,8 @@ static int hmm_vma_handle_pte(struct mm_ > * Since each architecture defines a struct page for the zero page, just > * fall through and treat it like a normal page. > */ > - if (pte_special(pte) && !pte_devmap(pte) && > + if (!vm_normal_page(walk->vma, addr, pte) && > + !pte_devmap(pte) && > !is_zero_pfn(pte_pfn(pte))) { > if (hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0)) { > pte_unmap(ptep); > @@ -518,7 +519,7 @@ static int hmm_vma_walk_test(unsigned lo > struct hmm_range *range = hmm_vma_walk->range; > struct vm_area_struct *vma = walk->vma; > > - if (!(vma->vm_flags & (VM_IO | VM_PFNMAP | VM_MIXEDMAP)) && > + if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)) && > vma->vm_flags & VM_READ) > return 0; > > --- a/tools/testing/selftests/vm/hmm-tests.c~mm-hmmc-allow-vm_mixedmap-to-work-with-hmm_range_fault > +++ a/tools/testing/selftests/vm/hmm-tests.c > @@ -1251,6 +1251,48 @@ TEST_F(hmm, anon_teardown) > /* > * Test memory snapshot without faulting in pages accessed by the device. > */ > +TEST_F(hmm, mixedmap) > +{ > + struct hmm_buffer *buffer; > + unsigned long npages; > + unsigned long size; > + unsigned char *m; > + int ret; > + > + npages = 1; > + size = npages << self->page_shift; > + > + buffer = malloc(sizeof(*buffer)); > + ASSERT_NE(buffer, NULL); > + > + buffer->fd = -1; > + buffer->size = size; > + buffer->mirror = malloc(npages); > + ASSERT_NE(buffer->mirror, NULL); > + > + > + /* Reserve a range of addresses. */ > + buffer->ptr = mmap(NULL, size, > + PROT_READ | PROT_WRITE, > + MAP_PRIVATE, > + self->fd, 0); > + ASSERT_NE(buffer->ptr, MAP_FAILED); > + > + /* Simulate a device snapshotting CPU pagetables. */ > + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages); > + ASSERT_EQ(ret, 0); > + ASSERT_EQ(buffer->cpages, npages); > + > + /* Check what the device saw. */ > + m = buffer->mirror; > + ASSERT_EQ(m[0], HMM_DMIRROR_PROT_READ); > + > + hmm_buffer_free(buffer); > +} > + > +/* > + * Test memory snapshot without faulting in pages accessed by the device. > + */ > TEST_F(hmm2, snapshot) > { > struct hmm_buffer *buffer; > _ > > >
diff --git a/lib/test_hmm.c b/lib/test_hmm.c index c259842f6d44..ac794e354069 100644 --- a/lib/test_hmm.c +++ b/lib/test_hmm.c @@ -1087,9 +1087,33 @@ static long dmirror_fops_unlocked_ioctl(struct file *filp, return 0; } +static int dmirror_fops_mmap(struct file *file, struct vm_area_struct *vma) +{ + unsigned long addr; + + for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) { + struct page *page; + int ret; + + page = alloc_page(GFP_KERNEL | __GFP_ZERO); + if (!page) + return -ENOMEM; + + ret = vm_insert_page(vma, addr, page); + if (ret) { + __free_page(page); + return ret; + } + put_page(page); + } + + return 0; +} + static const struct file_operations dmirror_fops = { .open = dmirror_fops_open, .release = dmirror_fops_release, + .mmap = dmirror_fops_mmap, .unlocked_ioctl = dmirror_fops_unlocked_ioctl, .llseek = default_llseek, .owner = THIS_MODULE, diff --git a/mm/hmm.c b/mm/hmm.c index fad6be2bf072..70fa81a3b629 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -298,7 +298,8 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, * Since each architecture defines a struct page for the zero page, just * fall through and treat it like a normal page. */ - if (pte_special(pte) && !is_zero_pfn(pte_pfn(pte))) { + if (!vm_normal_page(walk->vma, addr, pte) && + !is_zero_pfn(pte_pfn(pte))) { if (hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0)) { pte_unmap(ptep); return -EFAULT; @@ -515,7 +516,7 @@ static int hmm_vma_walk_test(unsigned long start, unsigned long end, struct hmm_range *range = hmm_vma_walk->range; struct vm_area_struct *vma = walk->vma; - if (!(vma->vm_flags & (VM_IO | VM_PFNMAP | VM_MIXEDMAP)) && + if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)) && vma->vm_flags & VM_READ) return 0; diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c index 864f126ffd78..203323967b50 100644 --- a/tools/testing/selftests/vm/hmm-tests.c +++ b/tools/testing/selftests/vm/hmm-tests.c @@ -1248,6 +1248,48 @@ TEST_F(hmm, anon_teardown) } } +/* + * Test memory snapshot without faulting in pages accessed by the device. + */ +TEST_F(hmm, mixedmap) +{ + struct hmm_buffer *buffer; + unsigned long npages; + unsigned long size; + unsigned char *m; + int ret; + + npages = 1; + size = npages << self->page_shift; + + buffer = malloc(sizeof(*buffer)); + ASSERT_NE(buffer, NULL); + + buffer->fd = -1; + buffer->size = size; + buffer->mirror = malloc(npages); + ASSERT_NE(buffer->mirror, NULL); + + + /* Reserve a range of addresses. */ + buffer->ptr = mmap(NULL, size, + PROT_READ | PROT_WRITE, + MAP_PRIVATE, + self->fd, 0); + ASSERT_NE(buffer->ptr, MAP_FAILED); + + /* Simulate a device snapshotting CPU pagetables. */ + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages); + ASSERT_EQ(ret, 0); + ASSERT_EQ(buffer->cpages, npages); + + /* Check what the device saw. */ + m = buffer->mirror; + ASSERT_EQ(m[0], HMM_DMIRROR_PROT_READ); + + hmm_buffer_free(buffer); +} + /* * Test memory snapshot without faulting in pages accessed by the device. */
hmm_range_fault() can be used instead of get_user_pages() for devices which allow faulting however unlike get_user_pages() it will return an error when used on a VM_MIXEDMAP range. To make hmm_range_fault() more closely match get_user_pages() remove this restriction. This requires dealing with the !ARCH_HAS_PTE_SPECIAL case in hmm_vma_handle_pte(). Rather than replicating the logic of vm_normal_page() call it directly and do a check for the zero pfn similar to what get_user_pages() currently does. Also add a test to hmm selftest to verify functionality. Signed-off-by: Alistair Popple <apopple@nvidia.com> --- lib/test_hmm.c | 24 +++++++++++++++ mm/hmm.c | 5 +-- tools/testing/selftests/vm/hmm-tests.c | 42 ++++++++++++++++++++++++++ 3 files changed, 69 insertions(+), 2 deletions(-)