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  1. Nov 08, 2023
    • Linus Torvalds's avatar
      Merge tag 'ovl-update-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs · 7f851936
      Linus Torvalds authored
      Pull overlayfs updates from Amir Goldstein:
      
       - Overlayfs aio cleanups and fixes
      
         Cleanups and minor fixes in preparation for factoring out of
         read/write passthrough code.
      
       - Overlayfs lock ordering changes
      
         Hold mnt_writers only throughout copy up instead of a long lived
         elevated refcount.
      
       - Add support for nesting overlayfs private xattrs
      
         There are cases where you want to use an overlayfs mount as a
         lowerdir for another overlayfs mount. For example, if the system
         rootfs is on overlayfs due to composefs, or to make it volatile (via
         tmpfs), then you cannot currently store a lowerdir on the rootfs,
         because the inner overlayfs will eat all the whiteouts and overlay
         xattrs. This means you can't e.g. store on the rootfs a prepared
         container image for use with overlayfs.
      
         This adds support for nesting of overlayfs mounts by escaping the
         problematic features and unescaping them when exposing to the
         overlayfs user.
      
       - Add new mount options for appending lowerdirs
      
      * tag 'ovl-update-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
        ovl: add support for appending lowerdirs one by one
        ovl: refactor layer parsing helpers
        ovl: store and show the user provided lowerdir mount option
        ovl: remove unused code in lowerdir param parsing
        ovl: Add documentation on nesting of overlayfs mounts
        ovl: Add an alternative type of whiteout
        ovl: Support escaped overlay.* xattrs
        ovl: Add OVL_XATTR_TRUSTED/USER_PREFIX_LEN macros
        ovl: Move xattr support to new xattrs.c file
        ovl: do not encode lower fh with upper sb_writers held
        ovl: do not open/llseek lower file with upper sb_writers held
        ovl: reorder ovl_want_write() after ovl_inode_lock()
        ovl: split ovl_want_write() into two helpers
        ovl: add helper ovl_file_modified()
        ovl: protect copying of realinode attributes to ovl inode
        ovl: punt write aio completion to workqueue
        ovl: propagate IOCB_APPEND flag on writes to realfile
        ovl: use simpler function to convert iocb to rw flags
      7f851936
    • Linus Torvalds's avatar
      Merge tag 'bcachefs-2023-11-5' of https://evilpiepirate.org/git/bcachefs · c9d01179
      Linus Torvalds authored
      Pull more bcachefs updates from Kent Overstreet:
       "Here's the second big bcachefs pull request. This brings your tree up
        to date with my master branch, which is what existing bcachefs users
        are currently running.
      
        New features:
         - rebalance_work btree (and metadata version 1.3): the rebalance
           thread no longer has to scan to find extents that need processing -
           big scalability improvement.
         - sb_errors superblock section: this adds counters for each fsck
           error type, since filesystem creation, along with the date of the
           most recent error. It'll get us better bug reports (since users do
           not typically report errors that fsck was able to fix), and I might
           add telemetry for this in the future.
      
        Fixes include:
         - multiple snapshot deletion fixes
         - members_v2 fixups
         - deleted_inodes btree fixes
         - copygc thread no longer spins when a device is full but has no
           fragmented buckets (i.e. rebalance needs to move data around
           instead)
         - a fix for a memory reclaim issue with the btree key cache: we're
           now careful not to hold the srcu read lock that blocks key cache
           reclaim for too long
         - an early allocator locking fix, from Brian
         - endianness fixes, from Brian
         - CONFIG_BCACHEFS_DEBUG_TRANSACTIONS no longer defaults to y, a big
           performance improvement on multithreaded workloads"
      
      * tag 'bcachefs-2023-11-5' of https://evilpiepirate.org/git/bcachefs: (70 commits)
        bcachefs: Improve stripe checksum error message
        bcachefs: Simplify, fix bch2_backpointer_get_key()
        bcachefs: kill thing_it_points_to arg to backpointer_not_found()
        bcachefs: bch2_ec_read_extent() now takes btree_trans
        bcachefs: bch2_stripe_to_text() now prints ptr gens
        bcachefs: Don't iterate over journal entries just for btree roots
        bcachefs: Break up bch2_journal_write()
        bcachefs: Replace ERANGE with private error codes
        bcachefs: bkey_copy() is no longer a macro
        bcachefs: x-macro-ify inode flags enum
        bcachefs: Convert bch2_fs_open() to darray
        bcachefs: Move __bch2_members_v2_get_mut to sb-members.h
        bcachefs: bch2_prt_datetime()
        bcachefs: CONFIG_BCACHEFS_DEBUG_TRANSACTIONS no longer defaults to y
        bcachefs: Add a comment for BTREE_INSERT_NOJOURNAL usage
        bcachefs: rebalance_work btree is not a snapshots btree
        bcachefs: Add missing printk newlines
        bcachefs: Fix recovery when forced to use JSET_NO_FLUSH journal entry
        bcachefs: .get_parent() should return an error pointer
        bcachefs: Fix bch2_delete_dead_inodes()
        ...
      c9d01179
  2. Nov 07, 2023
    • Linus Torvalds's avatar
      Merge tag 'media/v6.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media · be3ca57c
      Linus Torvalds authored
      Pull media updates from Mauro Carvalho Chehab:
      
       - the old V4L2 core videobuf kAPI was finally removed. All media
         drivers should now be using VB2 kAPI
      
       - new automotive driver: mgb4
      
       - new platform video driver: npcm-video
      
       - new sensor driver: mt9m114
      
       - new TI driver used in conjunction with Cadence CSI2RX IP to bridge
         TI-specific parts
      
       - ir-rx51 was removed and the N900 DT binding was moved to the
         pwm-ir-tx generic driver
      
       - drop atomisp-specific ov5693, using the upstream driver instead
      
       - the camss driver has gained RDI3 support for VFE 17x
      
       - the atomisp driver now detects ISP2400 or ISP2401 at run time. No
         need to set it up at build time anymore
      
       - lots of driver fixes, cleanups and improvements
      
      * tag 'media/v6.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (377 commits)
        media: nuvoton: VIDEO_NPCM_VCD_ECE should depend on ARCH_NPCM
        media: venus: Fix firmware path for resources
        media: venus: hfi_cmds: Replace one-element array with flex-array member and use __counted_by
        media: venus: hfi_parser: Add check to keep the number of codecs within range
        media: venus: hfi: add checks to handle capabilities from firmware
        media: venus: hfi: fix the check to handle session buffer requirement
        media: venus: hfi: add checks to perform sanity on queue pointers
        media: platform: cadence: select MIPI_DPHY dependency
        media: MAINTAINERS: Fix path for J721E CSI2RX bindings
        media: cec: meson: always include meson sub-directory in Makefile
        media: videobuf2: Fix IS_ERR checking in vb2_dc_put_userptr()
        media: platform: mtk-mdp3: fix uninitialized variable in mdp_path_config()
        media: mediatek: vcodec: using encoder device to alloc/free encoder memory
        media: imx-jpeg: notify source chagne event when the first picture parsed
        media: cx231xx: Use EP5_BUF_SIZE macro
        media: siano: Drop unnecessary error check for debugfs_create_dir/file()
        media: mediatek: vcodec: Handle invalid encoder vsi
        media: aspeed: Drop unnecessary error check for debugfs_create_file()
        Documentation: media: buffer.rst: fix V4L2_BUF_FLAG_PREPARED
        Documentation: media: gen-errors.rst: fix confusing ENOTTY description
        ...
      be3ca57c
  3. Nov 06, 2023
  4. Nov 05, 2023
    • Kees Cook's avatar
      firewire: Annotate struct fw_node with __counted_by · c12d7aa7
      Kees Cook authored
      Prepare for the coming implementation by GCC and Clang of the __counted_by
      attribute. Flexible array members annotated with __counted_by can have
      their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
      (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
      functions).
      
      As found with Coccinelle[1], add __counted_by for struct fw_node.
      
      [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
      
      
      
      Cc: Takashi Sakamoto <o-takashi@sakamocchi.jp>
      Cc: linux1394-devel@lists.sourceforge.net
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Reviewed-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
      Link: https://lore.kernel.org/r/20230922175334.work.335-kees@kernel.org
      
      
      Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
      c12d7aa7
    • Linus Torvalds's avatar
      Merge tag 'i3c/for-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux · 1c410411
      Linus Torvalds authored
      Pull i3c updates from Alexandre Belloni:
       "There are now more fixes because as stated in my previous pull
        request, people now have access to actual hardware.
      
        Core:
      
         - handle IBI in the proper order
      
        Drivers:
      
         - cdns: fix status register access
      
         - mipi-i3c-hci: many fixes now that the driver has been actually
           tested
      
         - svc: many IBI fixes, correct compatible string, fix hot join corner
           cases"
      
      * tag 'i3c/for-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (29 commits)
        i3c: master: handle IBIs in order they came
        i3c: master: mipi-i3c-hci: Fix a kernel panic for accessing DAT_data.
        i3c: master: svc: fix compatibility string mismatch with binding doc
        i3c: master: svc: fix random hot join failure since timeout error
        i3c: master: svc: fix SDA keep low when polling IBIWON timeout happen
        i3c: master: svc: fix check wrong status register in irq handler
        i3c: master: svc: fix ibi may not return mandatory data byte
        i3c: master: svc: fix wrong data return when IBI happen during start frame
        i3c: master: svc: fix race condition in ibi work thread
        i3c: Fix typo "Provisional ID" to "Provisioned ID"
        i3c: Fix potential refcount leak in i3c_master_register_new_i3c_devs
        i3c: mipi-i3c-hci: Resume controller after aborted transfer
        i3c: mipi-i3c-hci: Resume controller explicitly
        i3c: mipi-i3c-hci: Fix missing xfer->completion in hci_cmd_v1_daa()
        i3c: mipi-i3c-hci: Do not unmap region not mapped for transfer
        i3c: mipi-i3c-hci: Set number of SW enabled Ring Bundles earlier
        i3c: mipi-i3c-hci: Fix race between bus cleanup and interrupt
        i3c: mipi-i3c-hci: Set ring start request together with enable
        i3c: mipi-i3c-hci: Remove BUG() when Ring Abort request times out
        i3c: mipi-i3c-hci: Fix out of bounds access in hci_dma_irq_handler
        ...
      1c410411
    • Linus Torvalds's avatar
      Merge tag 'cxl-for-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl · b8cc56d0
      Linus Torvalds authored
      Pull CXL (Compute Express Link) updates from Dan Williams:
       "The main new functionality this time is work to allow Linux to
        natively handle CXL link protocol errors signalled via PCIe AER for
        current generation CXL platforms. This required some enlightenment of
        the PCIe AER core to workaround the fact that current generation RCH
        (Restricted CXL Host) platforms physically hide topology details and
        registers via a mechanism called RCRB (Root Complex Register Block).
      
        The next major highlight is reworks to address bugs in parsing region
        configurations for next generation VH (Virtual Host) topologies. The
        old broken algorithm is replaced with a simpler one that significantly
        increases the number of region configurations supported by Linux. This
        is again relevant for error handling so that forward and reverse
        address translation of memory errors can be carried out by Linux for
        memory regions instantiated by platform firmware.
      
        As for other cross-tree work, the ACPI table parsing code has been
        refactored for reuse parsing the "CDAT" structure which is an
        ACPI-like data structure that is reported by CXL devices. That work is
        in preparation for v6.8 support for CXL QoS. Think of this as dynamic
        generation of NUMA node topology information generated by Linux rather
        than platform firmware.
      
        Lastly, a number of internal object lifetime issues have been resolved
        along with misc. fixes and feature updates (decoders_committed sysfs
        ABI).
      
        Summary:
      
         - Add support for RCH (Restricted CXL Host) Error recovery
      
         - Fix several region assembly bugs
      
         - Fix mem-device lifetime issues relative to the sanitize command and
           RCH topology.
      
         - Refactor ACPI table parsing for CDAT parsing re-use in preparation
           for CXL QOS support"
      
      * tag 'cxl-for-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl: (50 commits)
        lib/fw_table: Remove acpi_parse_entries_array() export
        cxl/pci: Change CXL AER support check to use native AER
        cxl/hdm: Remove broken error path
        cxl/hdm: Fix && vs || bug
        acpi: Move common tables helper functions to common lib
        cxl: Add support for reading CXL switch CDAT table
        cxl: Add checksum verification to CDAT from CXL
        cxl: Export QTG ids from CFMWS to sysfs as qos_class attribute
        cxl: Add decoders_committed sysfs attribute to cxl_port
        cxl: Add cxl_decoders_committed() helper
        cxl/core/regs: Rework cxl_map_pmu_regs() to use map->dev for devm
        cxl/core/regs: Rename phys_addr in cxl_map_component_regs()
        PCI/AER: Unmask RCEC internal errors to enable RCH downstream port error handling
        PCI/AER: Forward RCH downstream port-detected errors to the CXL.mem dev handler
        cxl/pci: Disable root port interrupts in RCH mode
        cxl/pci: Add RCH downstream port error logging
        cxl/pci: Map RCH downstream AER registers for logging protocol errors
        cxl/pci: Update CXL error logging to use RAS register address
        PCI/AER: Refactor cper_print_aer() for use by CXL driver module
        cxl/pci: Add RCH downstream port AER register discovery
        ...
      b8cc56d0
    • Kent Overstreet's avatar
      bcachefs: CONFIG_BCACHEFS_DEBUG_TRANSACTIONS no longer defaults to y · bf61dcdf
      Kent Overstreet authored
      
      
      BCACHEFS_DEBUG_TRANSACTIONS is useful, but it's too expensive to have on
      by default - and it hasn't been coming up in bug reports.
      
      Turn it off by default until we figure out a way to make it cheaper.
      
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      bf61dcdf
    • Kent Overstreet's avatar
      bcachefs: Add a comment for BTREE_INSERT_NOJOURNAL usage · 9fcdd23b
      Kent Overstreet authored
      
      
      BTREE_INSERT_NOJOURNAL is primarily used for a performance optimization
      related to inode updates and fsync - document it.
      
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      9fcdd23b
    • Kent Overstreet's avatar
      bcachefs: rebalance_work btree is not a snapshots btree · d3c7727b
      Kent Overstreet authored
      
      
      rebalance_work entries may refer to entries in the extents btree, which
      is a snapshots btree, or they may also refer to entries in the reflink
      btree, which is not.
      
      Hence rebalance_work keys may use the snapshot field but it's not
      required to be nonzero - add a new btree flag to reflect this.
      
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      d3c7727b
    • Kent Overstreet's avatar
      bcachefs: Add missing printk newlines · 01ccee22
      Kent Overstreet authored
      
      
      This was causing error messages in -tools to not get printed.
      
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      01ccee22
    • Kent Overstreet's avatar
      bcachefs: Fix recovery when forced to use JSET_NO_FLUSH journal entry · 5a53f851
      Kent Overstreet authored
      
      
      When we didn't find anything in the journal that we'd like to use, and
      we're forced to use whatever we can find - that entry will have been a
      JSET_NO_FLUSH entry with a garbage last_seq value, since it's not
      normally used.
      
      Initialize it to something sane, for bch2_fs_journal_start().
      
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      5a53f851
    • Kent Overstreet's avatar
      bcachefs: .get_parent() should return an error pointer · ce3e9a8a
      Kent Overstreet authored
      
      
      Delete the useless check for inum == 0; we'll return -ENOENT without it,
      which is what we want.
      
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      ce3e9a8a
    • Kent Overstreet's avatar
      bcachefs: Fix bch2_delete_dead_inodes() · 4bd156c4
      Kent Overstreet authored
      
      
       - the fsck_err() check for the filesystem being clean was incorrect,
         causing us to always fail to delete unlinked inodes
       - if a snapshot had been taken, the unlinked inode needs to be
         propagated to snapshot leaves so the unlink can happen there - fixed.
      
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      4bd156c4
    • Brian Foster's avatar
      bcachefs: use swab40 for bch_backpointer.bucket_offset bitfield · 7cb2a789
      Brian Foster authored
      
      
      The bucket_offset field of bch_backpointer is a 40-bit bitfield, but the
      bch2_backpointer_swab() helper uses swab32. This leads to inconsistency
      when an on-disk fs is accessed from an opposite endian machine.
      
      As it turns out, we already have an internal swab40() helper that is
      used from the bch_alloc_v4 swab callback. Lift it into the backpointers
      header file and use it consistently in both places.
      
      Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      7cb2a789
    • Brian Foster's avatar
      bcachefs: byte order swap bch_alloc_v4.fragmentation_lru field · 0996c72a
      Brian Foster authored
      
      
      A simple test to populate a filesystem on one CPU architecture and
      fsck on an arch of the opposite byte order produces errors related
      to the fragmentation LRU. This occurs because the 64-bit
      fragmentation_lru field is not byte-order swapped when reads detect
      that the on-disk/bset key values were written in opposite byte-order
      of the current CPU.
      
      Update the bch2_alloc_v4 swab callback to handle fragmentation_lru
      as is done for other multi-byte fields. This doesn't affect existing
      filesystems when accessed by CPUs of the same endianness because the
      ->swab() callback is only called when the bset flags indicate an
      endianness mismatch between the CPU and on-disk data.
      
      Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      0996c72a
    • Brian Foster's avatar
      bcachefs: allow writeback to fill bio completely · 2a4e7497
      Brian Foster authored
      
      
      The bcachefs folio writeback code includes a bio full check as well
      as a fixed size check to determine when to split off and submit
      writeback I/O. The inclusive check of the latter against the limit
      means that writeback can submit slightly prematurely. This is not a
      functional problem, but results in unnecessarily split I/Os and
      extent merging.
      
      This can be observed with a buffered write sized exactly to the
      current maximum value (1MB) and with key_merging_disabled=1. The
      latter prevents the merge from the second write such that a
      subsequent check of the extent list shows a 1020k extent followed by
      a contiguous 4k extent.
      
      The purpose for the fixed size check is also undocumented and
      somewhat obscure. Lift this check into a new helper that wraps the
      bio check, fix the comparison logic, and add a comment to document
      the purpose and how we might improve on this in the future.
      
      Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      2a4e7497
    • Brian Foster's avatar
      bcachefs: fix odebug warn and lockdep splat due to on-stack rhashtable · 0e91d3a6
      Brian Foster authored
      
      
      Guenter Roeck reports a lockdep splat and DEBUG_OBJECTS_WORK related
      warning when bch2_copygc_thread() initializes its rhashtable. The
      lockdep splat relates to a warning print caused by the fact that the
      rhashtable exists on the stack but is not annotated as so. This is
      something that could be addressed by INIT_WORK_ONSTACK(), but
      rhashtable doesn't expose that control and probably isnt worth the
      churn for just one user. Instead, dynamically allocate the
      buckets_in_flight structure and avoid the splat that way.
      
      Reported-by: default avatarGuenter Roeck <linux@roeck-us.net>
      Tested-by: default avatarGuenter Roeck <linux@roeck-us.net>
      Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      0e91d3a6
    • Brian Foster's avatar
      bcachefs: update alloc cursor in early bucket allocator · e0fb0dcc
      Brian Foster authored
      
      
      A recent bug report uncovered a scenario where a filesystem never
      runs with freespace_initialized, and therefore the user observes
      significantly degraded write performance by virtue of running the
      early bucket allocator. The associated bug aside, the primary cause
      of the performance drop in this particular instance is that the
      early bucket allocator does not update the allocation cursor. This
      means that every allocation walks the alloc btree from the first
      bucket of the associated device looking for a bucket marked as free
      space.
      
      Update the early allocator code to set the alloc cursor to the last
      processed position in the tree, similar to how the freelist
      allocator behaves. With the alloc_cursor being updated, the retry
      logic also needs to be updated to restart from the beginning of the
      device when a free bucket is not available between the cursor and
      the end of the device. Track the restart position in a first_bucket
      variable to make the code a bit more easily readable and consistent
      with the freelist allocator.
      
      Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      e0fb0dcc
    • Brian Foster's avatar
      bcachefs: serialize on cached key in early bucket allocator · 385a82f6
      Brian Foster authored
      
      
      bcachefs had a transient bug where freespace_initialized was not
      properly being set, which lead to unexpected use of the early bucket
      allocator at runtime. This issue has been fixed, but the existence
      of it uncovered a coherency issue in the early bucket allocation
      code that is somewhat related to how uncached iterators deal with
      the key cache.
      
      The problem itself manifests as occasional failure of generic/113
      due to corruption, often seen as a duplicate backpointer or multiple
      data types per-bucket error. The immediate cause of the error is a
      racing bucket allocation along the lines of the following sequence:
      
      - Task 1 selects key A in bch2_bucket_alloc_early() and schedules.
      - Task 2 selects the same key A, but proceeds to complete the
        allocation and associated I/O, after which it releases the
        open_bucket.
      - Task 1 resumes with key A, but does not recognize the bucket is
        now allocated because the open_bucket has been removed
        from the hash when it was released in the previous step.
      
      This generally shouldn't happen because the allocating task updates
      the alloc btree key before releasing the bucket. This is not
      sufficient in this particular instance, however, because an uncached
      iterator for a cached btree doesn't actually lock the key cache slot
      when no key exists for a given slot in the cache. Thus the fact that
      the allocation side updates the cached key means that multiple
      uncached iters can stumble across the same alloc key and duplicate
      the bucket allocation as described above.
      
      This is something that probably needs a longer term fix in the
      iterator code. As a short term fix, close the race through explicit
      use of a cached iterator for likely allocation candidates. We don't
      want to scan the btree with a cached iterator because that would
      unnecessarily pollute the cache. This mitigates cache pollution by
      primarily scanning the tree with an uncached iterator, but closes
      the race by creating a key cache entry for any prospective slot
      prior to the bucket allocation attempt (also similar to how
      _alloc_freelist() works via try_alloc_bucket()). This survives many
      iterations of generic/113 on a kernel hacked to always use the early
      bucket allocator.
      
      Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
      Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
      385a82f6
    • Kent Overstreet's avatar
    • Linus Torvalds's avatar
      Merge tag 'tsm-for-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/linux · 5e2cb28d
      Linus Torvalds authored
      Pull unified attestation reporting from Dan Williams:
       "In an ideal world there would be a cross-vendor standard attestation
        report format for confidential guests along with a common device
        definition to act as the transport.
      
        In the real world the situation ended up with multiple platform
        vendors inventing their own attestation report formats with the
        SEV-SNP implementation being a first mover to define a custom
        sev-guest character device and corresponding ioctl(). Later, this
        configfs-tsm proposal intercepted an attempt to add a tdx-guest
        character device and a corresponding new ioctl(). It also anticipated
        ARM and RISC-V showing up with more chardevs and more ioctls().
      
        The proposal takes for granted that Linux tolerates the vendor report
        format differentiation until a standard arrives. From talking with
        folks involved, it sounds like that standardization work is unlikely
        to resolve anytime soon. It also takes the position that kernfs ABIs
        are easier to maintain than ioctl(). The result is a shared configfs
        mechanism to return per-vendor report-blobs with the option to later
        support a standard when that arrives.
      
        Part of the goal here also is to get the community into the
        "uncomfortable, but beneficial to the long term maintainability of the
        kernel" state of talking to each other about their differentiation and
        opportunities to collaborate. Think of this like the device-driver
        equivalent of the common memory-management infrastructure for
        confidential-computing being built up in KVM.
      
        As for establishing an "upstream path for cross-vendor
        confidential-computing device driver infrastructure" this is something
        I want to discuss at Plumbers. At present, the multiple vendor
        proposals for assigning devices to confidential computing VMs likely
        needs a new dedicated repository and maintainer team, but that is a
        discussion for v6.8.
      
        For now, Greg and Thomas have acked this approach and this is passing
        is AMD, Intel, and Google tests.
      
        Summary:
      
         - Introduce configfs-tsm as a shared ABI for confidential computing
           attestation reports
      
         - Convert sev-guest to additionally support configfs-tsm alongside
           its vendor specific ioctl()
      
         - Added signed attestation report retrieval to the tdx-guest driver
           forgoing a new vendor specific ioctl()
      
         - Misc cleanups and a new __free() annotation for kvfree()"
      
      * tag 'tsm-for-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/linux:
        virt: tdx-guest: Add Quote generation support using TSM_REPORTS
        virt: sevguest: Add TSM_REPORTS support for SNP_GET_EXT_REPORT
        mm/slab: Add __free() support for kvfree
        virt: sevguest: Prep for kernel internal get_ext_report()
        configfs-tsm: Introduce a shared ABI for attestation reports
        virt: coco: Add a coco/Makefile and coco/Kconfig
        virt: sevguest: Fix passing a stack buffer as a scatterlist target
      5e2cb28d