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2016-09-03dax: fix mapping size checkDan Williams
pgoff_to_phys() validates that both the starting address and the length of the mapping against the resource list. We need to check for a mapping size of PMD_SIZE not PAGE_SIZE in the pmd fault path. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-08-26dax: fix device-dax region baseDan Williams
The data offset for a dax region needs to account for a reservation in the resource range. Otherwise, device-dax is allowing mappings directly into the memmap or device-info-block area with crash signatures like the following: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 IP: get_zone_device_page+0x11/0x30 Call Trace: follow_devmap_pmd+0x298/0x2c0 follow_page_mask+0x275/0x530 __get_user_pages+0xe3/0x750 __gfn_to_pfn_memslot+0x1b2/0x450 [kvm] tdp_page_fault+0x130/0x280 [kvm] kvm_mmu_page_fault+0x5f/0xf0 [kvm] handle_ept_violation+0x94/0x180 [kvm_intel] vmx_handle_exit+0x1d3/0x1440 [kvm_intel] kvm_arch_vcpu_ioctl_run+0x81d/0x16a0 [kvm] kvm_vcpu_ioctl+0x33c/0x620 [kvm] do_vfs_ioctl+0xa2/0x5d0 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x1a/0xa4 Fixes: ab68f2622136 ("/dev/dax, pmem: direct access to persistent memory") Link: http://lkml.kernel.org/r/147205536732.1606.8994275381938837346.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reported-by: Abhilash Kumar Mulumudi <m.abhilash-kumar@hpe.com> Reported-by: Toshi Kani <toshi.kani@hpe.com> Tested-by: Toshi Kani <toshi.kani@hpe.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-06dax: use devm_add_action_or_reset()Sajjan, Vikas C
If devm_add_action() fails, we are explicitly calling the cleanup to free the resources allocated. Use the helper devm_add_action_or_reset() and return directly in case of error, since the cleanup function has been already called by the helper if there was any error. Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Signed-off-by: Vikas C Sajjan <vikas.cha.sajjan@hpe.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-05-20/dev/dax, core: file operations and dax-mmapDan Williams
The "Device DAX" core enables dax mappings of performance / feature differentiated memory. An open mapping or file handle keeps the backing struct device live, but new mappings are only possible while the device is enabled. Faults are handled under rcu_read_lock to synchronize with the enabled state of the device. Similar to the filesystem-dax case the backing memory may optionally have struct page entries. However, unlike fs-dax there is no support for private mappings, or mappings that are not backed by media (see use of zero-page in fs-dax). Mappings are always guaranteed to match the alignment of the dax_region. If the dax_region is configured to have a 2MB alignment, all mappings are guaranteed to be backed by a pmd entry. Contrast this determinism with the fs-dax case where pmd mappings are opportunistic. If userspace attempts to force a misaligned mapping, the driver will fail the mmap attempt. See dax_dev_check_vma() for other scenarios that are rejected, like MAP_PRIVATE mappings. Cc: Hannes Reinecke <hare@suse.de> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-05-20/dev/dax, pmem: direct access to persistent memoryDan Williams
Device DAX is the device-centric analogue of Filesystem DAX (CONFIG_FS_DAX). It allows memory ranges to be allocated and mapped without need of an intervening file system. Device DAX is strict, precise and predictable. Specifically this interface: 1/ Guarantees fault granularity with respect to a given page size (pte, pmd, or pud) set at configuration time. 2/ Enforces deterministic behavior by being strict about what fault scenarios are supported. For example, by forcing MADV_DONTFORK semantics and omitting MAP_PRIVATE support device-dax guarantees that a mapping always behaves/performs the same once established. It is the "what you see is what you get" access mechanism to differentiated memory vs filesystem DAX which has filesystem specific implementation semantics. Persistent memory is the first target, but the mechanism is also targeted for exclusive allocations of performance differentiated memory ranges. This commit is limited to the base device driver infrastructure to associate a dax device with pmem range. Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>