| Message ID | 20170417014239.25866.42333.stgit@gimli.home (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Apr 16, 2017 at 07:42:39PM -0600, Alex Williamson wrote: > With vfio_lock_acct() testing the locked memory limit under mmap_sem, > it's redundant to do it here for a single page. We can also reorder > our tests such that we can avoid testing for reserved pages if we're > not doing accounting, and test the process CAP_IPC_LOCK only if we > are doing accounting. Finally, this function oddly returns 1 on > success. Update to return zero on success, -errno on error. Since > the function only pins a single page, there's no need to return the > number of pages pinned. > > N.B. vfio_pin_pages_remote() can pin a large contiguous range of pages > before calling vfio_lock_acct(). If we were to similarly remove the > extra test there, a user could temporarily pin far more pages than > they're allowed. > > Suggested-by: Kirti Wankhede <kwankhede@nvidia.com> > Suggested-by: Peter Xu <peterx@redhat.com> Maybe this suggested-by honor should be for Kirti only? :) For the patch, I think it's good to me as long as we have the accounting check in vfio_lock_acct() which is just introduced in previous patch, so: Reviewed-by: Peter Xu <peterx@redhat.com> Thanks!
On Mon, 17 Apr 2017 14:54:21 +0800 Peter Xu <peterx@redhat.com> wrote: > On Sun, Apr 16, 2017 at 07:42:39PM -0600, Alex Williamson wrote: > > With vfio_lock_acct() testing the locked memory limit under mmap_sem, > > it's redundant to do it here for a single page. We can also reorder > > our tests such that we can avoid testing for reserved pages if we're > > not doing accounting, and test the process CAP_IPC_LOCK only if we > > are doing accounting. Finally, this function oddly returns 1 on > > success. Update to return zero on success, -errno on error. Since > > the function only pins a single page, there's no need to return the > > number of pages pinned. > > > > N.B. vfio_pin_pages_remote() can pin a large contiguous range of pages > > before calling vfio_lock_acct(). If we were to similarly remove the > > extra test there, a user could temporarily pin far more pages than > > they're allowed. > > > > Suggested-by: Kirti Wankhede <kwankhede@nvidia.com> > > Suggested-by: Peter Xu <peterx@redhat.com> > > Maybe this suggested-by honor should be for Kirti only? :) Sorry, I mis-attributed this, Eric suggested that vfio_pin_page_external() should have a standard return value. I'll change the Suggested-by. > For the patch, I think it's good to me as long as we have the > accounting check in vfio_lock_acct() which is just introduced in > previous patch, so: > > Reviewed-by: Peter Xu <peterx@redhat.com> Thanks!
On 4/17/2017 7:12 AM, Alex Williamson wrote: > With vfio_lock_acct() testing the locked memory limit under mmap_sem, > it's redundant to do it here for a single page. We can also reorder > our tests such that we can avoid testing for reserved pages if we're > not doing accounting, and test the process CAP_IPC_LOCK only if we > are doing accounting. Finally, this function oddly returns 1 on > success. Update to return zero on success, -errno on error. Since > the function only pins a single page, there's no need to return the > number of pages pinned. > > N.B. vfio_pin_pages_remote() can pin a large contiguous range of pages > before calling vfio_lock_acct(). If we were to similarly remove the > extra test there, a user could temporarily pin far more pages than > they're allowed. > > Suggested-by: Kirti Wankhede <kwankhede@nvidia.com> > Suggested-by: Peter Xu <peterx@redhat.com> > Signed-off-by: Alex Williamson <alex.williamson@redhat.com> > --- > drivers/vfio/vfio_iommu_type1.c | 34 +++++----------------------------- > 1 file changed, 5 insertions(+), 29 deletions(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index fb18e4a5df62..07e0e58f22e9 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -479,43 +479,21 @@ static long vfio_unpin_pages_remote(struct vfio_dma *dma, dma_addr_t iova, > static int vfio_pin_page_external(struct vfio_dma *dma, unsigned long vaddr, > unsigned long *pfn_base, bool do_accounting) > { > - unsigned long limit; > - bool lock_cap = has_capability(dma->task, CAP_IPC_LOCK); > struct mm_struct *mm; > int ret; > - bool rsvd; > > mm = get_task_mm(dma->task); > if (!mm) > return -ENODEV; > > ret = vaddr_get_pfn(mm, vaddr, dma->prot, pfn_base); > - if (ret) > - goto pin_page_exit; > - > - rsvd = is_invalid_reserved_pfn(*pfn_base); > - limit = task_rlimit(dma->task, RLIMIT_MEMLOCK) >> PAGE_SHIFT; > - > - if (!rsvd && !lock_cap && mm->locked_vm + 1 > limit) { > - put_pfn(*pfn_base, dma->prot); > - pr_warn("%s: Task %s (%d) RLIMIT_MEMLOCK (%ld) exceeded\n", > - __func__, dma->task->comm, task_pid_nr(dma->task), > - limit << PAGE_SHIFT); > - ret = -ENOMEM; > - goto pin_page_exit; > - } > - > - if (!rsvd && do_accounting) { > - ret = vfio_lock_acct(dma->task, 1, lock_cap); > - if (ret) { > + if (!ret && do_accounting && !is_invalid_reserved_pfn(*pfn_base)) { > + ret = vfio_lock_acct(dma->task, 1, > + has_capability(dma->task, CAP_IPC_LOCK)); > + if (ret) > put_pfn(*pfn_base, dma->prot); > - goto pin_page_exit; > - } > } > > - ret = 1; > - > -pin_page_exit: > mmput(mm); > return ret; > } Thanks. This looks clean. Just a nit pick, if vfio_lock_acct() returns -ENOMEM, its better to have warning about task's mlock limit exceeded, which got removed in the cleanup. No need to review again. Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com> Thanks, Kirti > @@ -595,10 +573,8 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data, > remote_vaddr = dma->vaddr + iova - dma->iova; > ret = vfio_pin_page_external(dma, remote_vaddr, &phys_pfn[i], > do_accounting); > - if (ret <= 0) { > - WARN_ON(!ret); > + if (ret) > goto pin_unwind; > - } > > ret = vfio_add_to_pfn_list(dma, iova, phys_pfn[i]); > if (ret) { >
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index fb18e4a5df62..07e0e58f22e9 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -479,43 +479,21 @@ static long vfio_unpin_pages_remote(struct vfio_dma *dma, dma_addr_t iova, static int vfio_pin_page_external(struct vfio_dma *dma, unsigned long vaddr, unsigned long *pfn_base, bool do_accounting) { - unsigned long limit; - bool lock_cap = has_capability(dma->task, CAP_IPC_LOCK); struct mm_struct *mm; int ret; - bool rsvd; mm = get_task_mm(dma->task); if (!mm) return -ENODEV; ret = vaddr_get_pfn(mm, vaddr, dma->prot, pfn_base); - if (ret) - goto pin_page_exit; - - rsvd = is_invalid_reserved_pfn(*pfn_base); - limit = task_rlimit(dma->task, RLIMIT_MEMLOCK) >> PAGE_SHIFT; - - if (!rsvd && !lock_cap && mm->locked_vm + 1 > limit) { - put_pfn(*pfn_base, dma->prot); - pr_warn("%s: Task %s (%d) RLIMIT_MEMLOCK (%ld) exceeded\n", - __func__, dma->task->comm, task_pid_nr(dma->task), - limit << PAGE_SHIFT); - ret = -ENOMEM; - goto pin_page_exit; - } - - if (!rsvd && do_accounting) { - ret = vfio_lock_acct(dma->task, 1, lock_cap); - if (ret) { + if (!ret && do_accounting && !is_invalid_reserved_pfn(*pfn_base)) { + ret = vfio_lock_acct(dma->task, 1, + has_capability(dma->task, CAP_IPC_LOCK)); + if (ret) put_pfn(*pfn_base, dma->prot); - goto pin_page_exit; - } } - ret = 1; - -pin_page_exit: mmput(mm); return ret; } @@ -595,10 +573,8 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data, remote_vaddr = dma->vaddr + iova - dma->iova; ret = vfio_pin_page_external(dma, remote_vaddr, &phys_pfn[i], do_accounting); - if (ret <= 0) { - WARN_ON(!ret); + if (ret) goto pin_unwind; - } ret = vfio_add_to_pfn_list(dma, iova, phys_pfn[i]); if (ret) {
With vfio_lock_acct() testing the locked memory limit under mmap_sem, it's redundant to do it here for a single page. We can also reorder our tests such that we can avoid testing for reserved pages if we're not doing accounting, and test the process CAP_IPC_LOCK only if we are doing accounting. Finally, this function oddly returns 1 on success. Update to return zero on success, -errno on error. Since the function only pins a single page, there's no need to return the number of pages pinned. N.B. vfio_pin_pages_remote() can pin a large contiguous range of pages before calling vfio_lock_acct(). If we were to similarly remove the extra test there, a user could temporarily pin far more pages than they're allowed. Suggested-by: Kirti Wankhede <kwankhede@nvidia.com> Suggested-by: Peter Xu <peterx@redhat.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com> --- drivers/vfio/vfio_iommu_type1.c | 34 +++++----------------------------- 1 file changed, 5 insertions(+), 29 deletions(-)