From: Ira Weiny <ira.weiny@xxxxxxxxx> Should a stray write in the kernel occur persistent memory is affected more than regular memory. A write to the wrong area of memory could result in latent data corruption which will will persist after a reboot. PKS provides a nice way to restrict access to persistent memory kernel mappings, while providing fast access when needed. Since the last RFC[1] this patch set has grown quite a bit. It now depends on the core patches submitted separately. https://lore.kernel.org/lkml/20201009194258.3207172-1-ira.weiny@xxxxxxxxx/ And contained in the git tree here: https://github.com/weiny2/linux-kernel/tree/pks-rfc-v3 However, functionally there is only 1 major change from the last RFC. Specifically, kmap() is most often used within a single thread in a 'map/do something/unmap' pattern. In fact this is the pattern used in ~90% of the callers of kmap(). This pattern works very well for the pmem use case and the testing which was done. However, there were another ~20-30 kmap users which do not follow this pattern. Some of them seem to expect the mapping to be 'global' while others require a detailed audit to be sure.[2][3] While we don't anticipate global mappings to pmem there is a danger in changing the semantics of kmap(). Effectively, this would cause an unresolved page fault with little to no information about why. There were a number of options considered. 1) Attempt to change all the thread local kmap() calls to kmap_atomic() 2) Introduce a flags parameter to kmap() to indicate if the mapping should be global or not 3) Change ~20-30 call sites to 'kmap_global()' to indicate that they require a global mapping of the pages 4) Change ~209 call sites to 'kmap_thread()' to indicate that the mapping is to be used within that thread of execution only Option 1 is simply not feasible kmap_atomic() is not the same semantic as kmap() within a single tread. Option 2 would require all of the call sites of kmap() to change. Option 3 seems like a good minimal change but there is a danger that new code may miss the semantic change of kmap() and not get the behavior intended for future users. Therefore, option #4 was chosen. To handle the global PKRS state in the most efficient manner possible. We lazily override the thread specific PKRS key value only when needed because we anticipate PKS to not be needed will not be needed most of the time. And even when it is used 90% of the time it is a thread local call. [1] https://lore.kernel.org/lkml/20200717072056.73134-1-ira.weiny@xxxxxxxxx/ [2] The following list of callers continue calling kmap() (utilizing the global PKRS). It would be nice if more of them could be converted to kmap_thread() drivers/firewire/net.c: ptr = kmap(dev->broadcast_rcv_buffer.pages[u]); drivers/gpu/drm/i915/gem/i915_gem_pages.c: return kmap(sg_page(sgt->sgl)); drivers/gpu/drm/ttm/ttm_bo_util.c: map->virtual = kmap(map->page); drivers/infiniband/hw/qib/qib_user_sdma.c: mpage = kmap(page); drivers/misc/vmw_vmci/vmci_host.c: context->notify = kmap(context->notify_page) + (uva & (PAGE_SIZE - 1)); drivers/misc/xilinx_sdfec.c: addr = kmap(pages[i]); drivers/mmc/host/usdhi6rol0.c: host->pg.mapped = kmap(host->pg.page); drivers/mmc/host/usdhi6rol0.c: host->pg.mapped = kmap(host->pg.page); drivers/mmc/host/usdhi6rol0.c: host->pg.mapped = kmap(host->pg.page); drivers/nvme/target/tcp.c: iov->iov_base = kmap(sg_page(sg)) + sg->offset + sg_offset; drivers/scsi/libiscsi_tcp.c: segment->sg_mapped = kmap(sg_page(sg)); drivers/target/iscsi/iscsi_target.c: iov[i].iov_base = kmap(sg_page(sg)) + sg->offset + page_off; drivers/target/target_core_transport.c: return kmap(sg_page(sg)) + sg->offset; fs/btrfs/check-integrity.c: block_ctx->datav[i] = kmap(block_ctx->pagev[i]); fs/ceph/dir.c: cache_ctl->dentries = kmap(cache_ctl->page); fs/ceph/inode.c: ctl->dentries = kmap(ctl->page); fs/erofs/zpvec.h: kmap_atomic(ctor->curr) : kmap(ctor->curr); lib/scatterlist.c: miter->addr = kmap(miter->page) + miter->__offset; net/ceph/pagelist.c: pl->mapped_tail = kmap(page); net/ceph/pagelist.c: pl->mapped_tail = kmap(page); virt/kvm/kvm_main.c: hva = kmap(page); [3] The following appear to follow the same pattern as ext2 which was converted after some code audit. So I _think_ they too could be converted to k[un]map_thread(). fs/freevxfs/vxfs_subr.c|75| kmap(pp); fs/jfs/jfs_metapage.c|102| kmap(page); fs/jfs/jfs_metapage.c|156| kmap(page); fs/minix/dir.c|72| kmap(page); fs/nilfs2/dir.c|195| kmap(page); fs/nilfs2/ifile.h|24| void *kaddr = kmap(ibh->b_page); fs/ntfs/aops.h|78| kmap(page); fs/ntfs/compress.c|574| kmap(page); fs/qnx6/dir.c|32| kmap(page); fs/qnx6/dir.c|58| kmap(*p = page); fs/qnx6/inode.c|190| kmap(page); fs/qnx6/inode.c|557| kmap(page); fs/reiserfs/inode.c|2397| kmap(bh_result->b_page); fs/reiserfs/xattr.c|444| kmap(page); fs/sysv/dir.c|60| kmap(page); fs/sysv/dir.c|262| kmap(page); fs/ufs/dir.c|194| kmap(page); fs/ufs/dir.c|562| kmap(page); Ira Weiny (58): x86/pks: Add a global pkrs option x86/pks/test: Add testing for global option memremap: Add zone device access protection kmap: Add stray access protection for device pages kmap: Introduce k[un]map_thread kmap: Introduce k[un]map_thread debugging drivers/drbd: Utilize new kmap_thread() drivers/firmware_loader: Utilize new kmap_thread() drivers/gpu: Utilize new kmap_thread() drivers/rdma: Utilize new kmap_thread() drivers/net: Utilize new kmap_thread() fs/afs: Utilize new kmap_thread() fs/btrfs: Utilize new kmap_thread() fs/cifs: Utilize new kmap_thread() fs/ecryptfs: Utilize new kmap_thread() fs/gfs2: Utilize new kmap_thread() fs/nilfs2: Utilize new kmap_thread() fs/hfs: Utilize new kmap_thread() fs/hfsplus: Utilize new kmap_thread() fs/jffs2: Utilize new kmap_thread() fs/nfs: Utilize new kmap_thread() fs/f2fs: Utilize new kmap_thread() fs/fuse: Utilize new kmap_thread() fs/freevxfs: Utilize new kmap_thread() fs/reiserfs: Utilize new kmap_thread() fs/zonefs: Utilize new kmap_thread() fs/ubifs: Utilize new kmap_thread() fs/cachefiles: Utilize new kmap_thread() fs/ntfs: Utilize new kmap_thread() fs/romfs: Utilize new kmap_thread() fs/vboxsf: Utilize new kmap_thread() fs/hostfs: Utilize new kmap_thread() fs/cramfs: Utilize new kmap_thread() fs/erofs: Utilize new kmap_thread() fs: Utilize new kmap_thread() fs/ext2: Use ext2_put_page fs/ext2: Utilize new kmap_thread() fs/isofs: Utilize new kmap_thread() fs/jffs2: Utilize new kmap_thread() net: Utilize new kmap_thread() drivers/target: Utilize new kmap_thread() drivers/scsi: Utilize new kmap_thread() drivers/mmc: Utilize new kmap_thread() drivers/xen: Utilize new kmap_thread() drivers/firmware: Utilize new kmap_thread() drives/staging: Utilize new kmap_thread() drivers/mtd: Utilize new kmap_thread() drivers/md: Utilize new kmap_thread() drivers/misc: Utilize new kmap_thread() drivers/android: Utilize new kmap_thread() kernel: Utilize new kmap_thread() mm: Utilize new kmap_thread() lib: Utilize new kmap_thread() powerpc: Utilize new kmap_thread() samples: Utilize new kmap_thread() dax: Stray access protection for dax_direct_access() nvdimm/pmem: Stray access protection for pmem->virt_addr [dax|pmem]: Enable stray access protection Documentation/core-api/protection-keys.rst | 11 +- arch/powerpc/mm/mem.c | 4 +- arch/x86/entry/common.c | 28 +++ arch/x86/include/asm/pkeys.h | 6 +- arch/x86/include/asm/pkeys_common.h | 8 +- arch/x86/kernel/process.c | 74 ++++++- arch/x86/mm/fault.c | 193 ++++++++++++++---- arch/x86/mm/pkeys.c | 88 ++++++-- drivers/android/binder_alloc.c | 4 +- drivers/base/firmware_loader/fallback.c | 4 +- drivers/base/firmware_loader/main.c | 4 +- drivers/block/drbd/drbd_main.c | 4 +- drivers/block/drbd/drbd_receiver.c | 12 +- drivers/dax/device.c | 2 + drivers/dax/super.c | 2 + drivers/firmware/efi/capsule-loader.c | 6 +- drivers/firmware/efi/capsule.c | 4 +- drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 12 +- drivers/gpu/drm/gma500/gma_display.c | 4 +- drivers/gpu/drm/gma500/mmu.c | 10 +- drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 4 +- .../drm/i915/gem/selftests/i915_gem_context.c | 4 +- .../drm/i915/gem/selftests/i915_gem_mman.c | 8 +- drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c | 4 +- drivers/gpu/drm/i915/gt/intel_gtt.c | 4 +- drivers/gpu/drm/i915/gt/shmem_utils.c | 4 +- drivers/gpu/drm/i915/i915_gem.c | 8 +- drivers/gpu/drm/i915/i915_gpu_error.c | 4 +- drivers/gpu/drm/i915/selftests/i915_perf.c | 4 +- drivers/gpu/drm/radeon/radeon_ttm.c | 4 +- drivers/infiniband/hw/hfi1/sdma.c | 4 +- drivers/infiniband/hw/i40iw/i40iw_cm.c | 10 +- drivers/infiniband/sw/siw/siw_qp_tx.c | 14 +- drivers/md/bcache/request.c | 4 +- drivers/misc/vmw_vmci/vmci_queue_pair.c | 12 +- drivers/mmc/host/mmc_spi.c | 4 +- drivers/mmc/host/sdricoh_cs.c | 4 +- drivers/mtd/mtd_blkdevs.c | 12 +- drivers/net/ethernet/intel/igb/igb_ethtool.c | 4 +- .../net/ethernet/intel/ixgbe/ixgbe_ethtool.c | 4 +- drivers/nvdimm/pmem.c | 6 + drivers/scsi/ipr.c | 8 +- drivers/scsi/pmcraid.c | 8 +- drivers/staging/rts5208/rtsx_transport.c | 4 +- drivers/target/target_core_iblock.c | 4 +- drivers/target/target_core_rd.c | 4 +- drivers/target/target_core_transport.c | 4 +- drivers/xen/gntalloc.c | 4 +- fs/afs/dir.c | 16 +- fs/afs/dir_edit.c | 16 +- fs/afs/mntpt.c | 4 +- fs/afs/write.c | 4 +- fs/aio.c | 4 +- fs/binfmt_elf.c | 4 +- fs/binfmt_elf_fdpic.c | 4 +- fs/btrfs/check-integrity.c | 4 +- fs/btrfs/compression.c | 4 +- fs/btrfs/inode.c | 16 +- fs/btrfs/lzo.c | 24 +-- fs/btrfs/raid56.c | 34 +-- fs/btrfs/reflink.c | 8 +- fs/btrfs/send.c | 4 +- fs/btrfs/zlib.c | 32 +-- fs/btrfs/zstd.c | 20 +- fs/cachefiles/rdwr.c | 4 +- fs/cifs/cifsencrypt.c | 6 +- fs/cifs/file.c | 16 +- fs/cifs/smb2ops.c | 8 +- fs/cramfs/inode.c | 10 +- fs/ecryptfs/crypto.c | 8 +- fs/ecryptfs/read_write.c | 8 +- fs/erofs/super.c | 4 +- fs/erofs/xattr.c | 4 +- fs/exec.c | 10 +- fs/ext2/dir.c | 8 +- fs/ext2/ext2.h | 8 + fs/ext2/namei.c | 15 +- fs/f2fs/f2fs.h | 8 +- fs/freevxfs/vxfs_immed.c | 4 +- fs/fuse/readdir.c | 4 +- fs/gfs2/bmap.c | 4 +- fs/gfs2/ops_fstype.c | 4 +- fs/hfs/bnode.c | 14 +- fs/hfs/btree.c | 20 +- fs/hfsplus/bitmap.c | 20 +- fs/hfsplus/bnode.c | 102 ++++----- fs/hfsplus/btree.c | 18 +- fs/hostfs/hostfs_kern.c | 12 +- fs/io_uring.c | 4 +- fs/isofs/compress.c | 4 +- fs/jffs2/file.c | 8 +- fs/jffs2/gc.c | 4 +- fs/nfs/dir.c | 20 +- fs/nilfs2/alloc.c | 34 +-- fs/nilfs2/cpfile.c | 4 +- fs/ntfs/aops.c | 4 +- fs/reiserfs/journal.c | 4 +- fs/romfs/super.c | 4 +- fs/splice.c | 4 +- fs/ubifs/file.c | 16 +- fs/vboxsf/file.c | 12 +- fs/zonefs/super.c | 4 +- include/linux/entry-common.h | 3 + include/linux/highmem.h | 63 +++++- include/linux/memremap.h | 1 + include/linux/mm.h | 43 ++++ include/linux/pkeys.h | 6 +- include/linux/sched.h | 8 + include/trace/events/kmap_thread.h | 56 +++++ init/init_task.c | 6 + kernel/fork.c | 18 ++ kernel/kexec_core.c | 8 +- lib/Kconfig.debug | 8 + lib/iov_iter.c | 12 +- lib/pks/pks_test.c | 138 +++++++++++-- lib/test_bpf.c | 4 +- lib/test_hmm.c | 8 +- mm/Kconfig | 13 ++ mm/debug.c | 23 +++ mm/memory.c | 8 +- mm/memremap.c | 90 ++++++++ mm/swapfile.c | 4 +- mm/userfaultfd.c | 4 +- net/ceph/messenger.c | 4 +- net/core/datagram.c | 4 +- net/core/sock.c | 8 +- net/ipv4/ip_output.c | 4 +- net/sunrpc/cache.c | 4 +- net/sunrpc/xdr.c | 8 +- net/tls/tls_device.c | 4 +- samples/vfio-mdev/mbochs.c | 4 +- 131 files changed, 1284 insertions(+), 565 deletions(-) create mode 100644 include/trace/events/kmap_thread.h -- 2.28.0.rc0.12.gb6a658bd00c9 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
