Pull more bcachefs fixes from Kent Overstreet:
 "Notable user impacting bugs

   - On multi device filesystems, recovery was looping in
     btree_trans_too_many_iters(). This checks if a transaction has
     touched too many btree paths (because of iteration over many keys),
     and isuses a restart to drop unneeded paths.

     But it's now possible for some paths to exceed the previous limit
     without iteration in the interior btree update path, since the
     transaction commit will do alloc updates for every old and new
     btree node, and during journal replay we don't use the btree write
     buffer for locking reasons and thus those updates use btree paths
     when they wouldn't normally.

   - Fix a corner case in rebalance when moving extents on a
     durability=0 device. This wouldn't be hit when a device was
     formatted with durability=0 since in that case we'll only use it as
     a write through cache (only cached extents will live on it), but
     durability can now be changed on an existing device.

   - bch2_get_acl() could rarely forget to handle a transaction restart;
     this manifested as the occasional missing acl that came back after
     dropping caches.

   - Fix a major performance regression on high iops multithreaded write
     workloads (only since 6.9-rc1); a previous fix for a deadlock in
     the interior btree update path to check the journal watermark
     introduced a dependency on the state of btree write buffer flushing
     that we didn't want.

   - Assorted other repair paths and recovery fixes"

* tag 'bcachefs-2024-04-10' of https://evilpiepirate.org/git/bcachefs: (25 commits)
  bcachefs: Fix __bch2_btree_and_journal_iter_init_node_iter()
  bcachefs: Kill read lock dropping in bch2_btree_node_lock_write_nofail()
  bcachefs: Fix a race in btree_update_nodes_written()
  bcachefs: btree_node_scan: Respect member.data_allowed
  bcachefs: Don't scan for btree nodes when we can reconstruct
  bcachefs: Fix check_topology() when using node scan
  bcachefs: fix eytzinger0_find_gt()
  bcachefs: fix bch2_get_acl() transaction restart handling
  bcachefs: fix the count of nr_freed_pcpu after changing bc->freed_nonpcpu list
  bcachefs: Fix gap buffer bug in bch2_journal_key_insert_take()
  bcachefs: Rename struct field swap to prevent macro naming collision
  MAINTAINERS: Add entry for bcachefs documentation
  Documentation: filesystems: Add bcachefs toctree
  bcachefs: JOURNAL_SPACE_LOW
  bcachefs: Disable errors=panic for BCH_IOCTL_FSCK_OFFLINE
  bcachefs: Fix BCH_IOCTL_FSCK_OFFLINE for encrypted filesystems
  bcachefs: fix rand_delete unit test
  bcachefs: fix ! vs ~ typo in __clear_bit_le64()
  bcachefs: Fix rebalance from durability=0 device
  bcachefs: Print shutdown journal sequence number
  ...

Merge tag 'tag-chrome-platform-fixes-for-v6.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux

Pull chrome platform fix from Tzung-Bi Shih:
 "Fix a NULL pointer dereference"

* tag 'tag-chrome-platform-fixes-for-v6.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux:
  platform/chrome: cros_ec_uart: properly fix race condition

Merge tag 'probes-fixes-v6.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probes fixes from Masami Hiramatsu:
 "Fix possible use-after-free issue on kprobe registration.

  check_kprobe_address_safe() uses `is_module_text_address()` and
  `__module_text_address()` separately.

  As a result, if the probed address is in a module that is being
  unloaded, the first `is_module_text_address()` might return true but
  then the `__module_text_address()` call might return NULL if the
  module has been unloaded between the two.

  The result is that kprobe believes the probe is on the kernel text,
  and skips getting a module reference. In this case, when it arms a
  breakpoint on the probe address, it may cause a use-after-free.

  To fix this issue, only use `__module_text_address()` once and get a
  reference to the module then. If it fails, reject the probe"

* tag 'probes-fixes-v6.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  kprobes: Fix possible use-after-free issue on kprobe registration

Merge tag 'bootconfig-fixes-v6.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull bootconfig fixes from Masami Hiramatsu:

 - show the original cmdline only once, and only if it was modeified by
   bootconfig

* tag 'bootconfig-fixes-v6.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  fs/proc: Skip bootloader comment if no embedded kernel parameters
  fs/proc: remove redundant comments from /proc/bootconfig

We weren't respecting trans->journal_replay_not_finished - we shouldn't
be searching the journal keys unless we have a ref on them.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

dropping read locks in bch2_btree_node_lock_write_nofail() dates from
before we had the cycle detector; we can now tell the cycle detector
directly when taking a lock may not fail because we can't handle
transaction restarts.

This is needed for adding should_be_locked asserts.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

One btree update might have terminated in a node update, and then while
it is in flight another btree update might free that original node.

This race has to be handled in btree_update_nodes_written() - we were
missing a READ_ONCE().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

The cros_ec_uart_probe() function calls devm_serdev_device_open() before
it calls serdev_device_set_client_ops(). This can trigger a NULL pointer
dereference:

    BUG: kernel NULL pointer dereference, address: 0000000000000000
    ...
    Call Trace:
     <TASK>
     ...
     ? ttyport_receive_buf

A simplified version of crashing code is as follows:

    static inline size_t serdev_controller_receive_buf(struct serdev_controller *ctrl,
                                                      const u8 *data,
                                                      size_t count)
    {
            struct serdev_device *serdev = ctrl->serdev;

            if (!serdev || !serdev->ops->receive_buf) // CRASH!
                return 0;

            return serdev->ops->receive_buf(serdev, data, count);
    }

It assumes that if SERPORT_ACTIVE is set and serdev exists, serdev->ops
will also exist. This conflicts with the existing cros_ec_uart_probe()
logic, as it first calls devm_serdev_device_open() (which sets
SERPORT_ACTIVE), and only later sets serdev->ops via
serdev_device_set_client_ops().

Commit 01f95d42 ("platform/chrome: cros_ec_uart: fix race
condition") attempted to fix a similar race condition, but while doing
so, made the window of error for this race condition to happen much
wider.

Attempt to fix the race condition again, making sure we fully setup
before calling devm_serdev_device_open().

Fixes: 01f95d42 ("platform/chrome: cros_ec_uart: fix race condition")
Cc: stable@vger.kernel.org
Signed-off-by: Noah Loomans <noah@noahloomans.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Link: https://lore.kernel.org/r/20240410182618.169042-2-noah@noahloomans.comSigned-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

Pull media fixes from Mauro Carvalho Chehab:

 - some fixes for mediatec vcodec encoder/decoder oopses

* tag 'media/v6.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
  media: mediatek: vcodec: support 36 bits physical address
  media: mediatek: vcodec: adding lock to protect encoder context list
  media: mediatek: vcodec: adding lock to protect decoder context list
  media: mediatek: vcodec: Fix oops when HEVC init fails
  media: mediatek: vcodec: Handle VP9 superframe bitstream with 8 sub-frames

Pull hardening fixes from Kees Cook:

 - gcc-plugins/stackleak: Avoid .head.text section (Ard Biesheuvel)

 - ubsan: fix unused variable warning in test module (Arnd Bergmann)

 - Improve entropy diffusion in randomize_kstack

* tag 'hardening-v6.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  randomize_kstack: Improve entropy diffusion
  ubsan: fix unused variable warning in test module
  gcc-plugins/stackleak: Avoid .head.text section

Pull turbostat updates from Len Brown:

 - Use of the CPU MSR driver is now optional

 - Perf is now preferred for many counters

 - Non-root users can now execute turbostat, though with limited
   functionality

 - Add counters for some new GFX hardware

 - Minor fixes

* tag 'turbostat-2024.04.10' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux: (26 commits)
  tools/power turbostat: v2024.04.10
  tools/power/turbostat: Add support for Xe sysfs knobs
  tools/power/turbostat: Add support for new i915 sysfs knobs
  tools/power/turbostat: Introduce BIC_SAM_mc6/BIC_SAMMHz/BIC_SAMACTMHz
  tools/power/turbostat: Fix uncore frequency file string
  tools/power/turbostat: Unify graphics sysfs snapshots
  tools/power/turbostat: Cache graphics sysfs path
  tools/power/turbostat: Enable MSR_CORE_C1_RES support for ICX
  tools/power turbostat: Add selftests
  tools/power turbostat: read RAPL counters via perf
  tools/power turbostat: Add proper re-initialization for perf file descriptors
  tools/power turbostat: Clear added counters when in no-msr mode
  tools/power turbostat: add early exits for permission checks
  tools/power turbostat: detect and disable unavailable BICs at runtime
  tools/power turbostat: Add reading aperf and mperf via perf API
  tools/power turbostat: Add --no-perf option
  tools/power turbostat: Add --no-msr option
  tools/power turbostat: enhance -D (debug counter dump) output
  tools/power turbostat: Fix warning upon failed /dev/cpu_dma_latency read
  tools/power turbostat: Read base_hz and bclk from CPUID.16H if available
  ...

Merge tag 'platform-drivers-x86-v6.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86

Pull x86 platform driver fixes from Ilpo Järvinen:
 "Fixes:

   - intel/hid: Solve spurious hibernation aborts (power button release)

   - toshiba_acpi: Ignore 2 keys to avoid log noise during
     suspend/resume

   - intel-vbtn: Fix probe by restoring VBDL and VGBS evalutation order

   - lg-laptop: Fix W=1 %s null argument warning

  New HW Support:

   - acer-wmi: PH18-71 mode button and fan speed sensor

   - intel/hid: Lunar Lake and Arrow Lake HID IDs"

* tag 'platform-drivers-x86-v6.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86:
  platform/x86: lg-laptop: fix %s null argument warning
  platform/x86: intel-vbtn: Update tablet mode switch at end of probe
  platform/x86: intel-vbtn: Use acpi_has_method to check for switch
  platform/x86: toshiba_acpi: Silence logging for some events
  platform/x86/intel/hid: Add Lunar Lake and Arrow Lake support
  platform/x86/intel/hid: Don't wake on 5-button releases
  platform/x86: acer-wmi: Add support for Acer PH18-71

When unloading a module, its state is changing MODULE_STATE_LIVE ->
 MODULE_STATE_GOING -> MODULE_STATE_UNFORMED. Each change will take
a time. `is_module_text_address()` and `__module_text_address()`
works with MODULE_STATE_LIVE and MODULE_STATE_GOING.
If we use `is_module_text_address()` and `__module_text_address()`
separately, there is a chance that the first one is succeeded but the
next one is failed because module->state becomes MODULE_STATE_UNFORMED
between those operations.

In `check_kprobe_address_safe()`, if the second `__module_text_address()`
is failed, that is ignored because it expected a kernel_text address.
But it may have failed simply because module->state has been changed
to MODULE_STATE_UNFORMED. In this case, arm_kprobe() will try to modify
non-exist module text address (use-after-free).

To fix this problem, we should not use separated `is_module_text_address()`
and `__module_text_address()`, but use only `__module_text_address()`
once and do `try_module_get(module)` which is only available with
MODULE_STATE_LIVE.

Link: https://lore.kernel.org/all/20240410015802.265220-1-zhengyejian1@huawei.com/

Fixes: 28f6c37a ("kprobes: Forbid probing on trampoline and BPF code areas")
Cc: stable@vger.kernel.org
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Much of turbostat can now run with perf, rather than using the MSR driver

Some of turbostat can now run as a regular non-root user.

Add some new output columns for some new GFX hardware.

[This patch updates the version, but otherwise changes no function;
 it touches up some checkpatch issues from previous patches]
Signed-off-by: Len Brown <len.brown@intel.com>

Xe graphics driver uses different graphics sysfs knobs including
   /sys/class/drm/card0/device/tile0/gt0/gtidle/idle_residency_ms
   /sys/class/drm/card0/device/tile0/gt0/freq0/cur_freq
   /sys/class/drm/card0/device/tile0/gt0/freq0/act_freq
   /sys/class/drm/card0/device/tile0/gt1/gtidle/idle_residency_ms
   /sys/class/drm/card0/device/tile0/gt1/freq0/cur_freq
   /sys/class/drm/card0/device/tile0/gt1/freq0/act_freq

Plus that,
   /sys/class/drm/card0/device/tile0/gt<n>/gtidle/name
returns either gt<n>-rc or gt<n>-mc. rc is for GFX and mc is SA Media.

Enhance turbostat to prefer the Xe sysfs knobs when they are available.
Export gt<n>-rc via BIC_GFX_rc6/BIC_GFXMHz/BIC_GFXACTMHz.
Export gt<n>-mc via BIC_SMA_mc6/BIC_SMAMHz/BIC_SMAACTMHz.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

On Meteorlake platform, i915 driver supports the traditional graphics
sysfs knobs including
   /sys/class/drm/card0/power/rc6_residency_ms
   /sys/class/drm/card0/gt_cur_freq_mhz
   /sys/class/drm/card0/gt_act_freq_mhz

At the same time, it also supports
   /sys/class/drm/card0/gt/gt0/rc6_residency_ms
   /sys/class/drm/card0/gt/gt0/rps_cur_freq_mhz
   /sys/class/drm/card0/gt/gt0/rps_act_freq_mhz
   /sys/class/drm/card0/gt/gt1/rc6_residency_ms
   /sys/class/drm/card0/gt/gt1/rps_cur_freq_mhz
   /sys/class/drm/card0/gt/gt1/rps_act_freq_mhz
gt0 is for GFX and gt1 is for SA Media.

Enhance turbostat to prefer the i915 new sysfs knobs.
Export gt0 via BIC_GFX_rc6/BIC_GFXMHz/BIC_GFXACTMHz.
Export gt1 via BIC_SMA_mc6/BIC_SMAMHz/BIC_SMAACTMHz.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

Graphics driver (i915/Xe) on mordern platforms splits GFX and SA Media
information via different sysfs knobs.

Existing BIC_GFX_rc6/BIC_GFXMHz/BIC_GFXACTMHz columns can be reused for
GFX.

Introduce BIC_SAM_mc6/BIC_SAMMHz/BIC_SAMACTMHz columns for SA Media.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

If a device wasn't used for btree nodes, no need to scan for them.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Running turbostat on a 16 socket HPE Scale-up Compute 3200 (SapphireRapids) fails with:
turbostat: /sys/devices/system/cpu/intel_uncore_frequency/package_010_die_00/current_freq_khz: open failed: No such file or directory

We observe the sysfs uncore frequency directories named:
...
package_09_die_00/
package_10_die_00/
package_11_die_00/
...
package_15_die_00/

The culprit is an incorrect sprintf format string "package_0%d_die_0%d" used
with each instance of reading uncore frequency files. uncore-frequency-common.c
creates the sysfs directory with the format "package_%02d_die_%02d". Once the
package value reaches double digits, the formats diverge.

Change each instance of "package_0%d_die_0%d" to "package_%02d_die_%02d".

[lenb: deleted the probe part of this patch, as it was already fixed]
Signed-off-by: Justin Ernst <justin.ernst@hpe.com>
Reviewed-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

Graphics sysfs snapshots share similar logic.
Combine them into one function to avoid code duplication.

No functional change.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

Graphics drivers (i915/Xe) have different sysfs knobs on different
platforms, and it is possible that different sysfs knobs fit into the
same turbostat columns.

Instead of specifying different sysfs knobs every time, detect them
once and cache the path for future use.

No functional change.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

Enable Core C1 hardware residency counter (MSR_CORE_C1_RES) on ICX.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

Signed-off-by: Patryk Wlazlyn <patryk.wlazlyn@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

Some of the future Intel platforms will require reading the RAPL
counters via perf and not MSR. On current platforms we can still read
them using both ways.
Signed-off-by: Patryk Wlazlyn <patryk.wlazlyn@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

Pull drm nouveau fix from Dave Airlie:
 "A previous fix to nouveau devinit on the GSP paths fixed the Turing
  but broke Ampere, I did some more digging and found the proper fix.
  Sending it early as I want to make sure it makes the next 6.8 stable
  kernels to fix the regression.

  Regular fixes will be at end of week as usual.

  nouveau:

   - regression fix for GSP display enable"

* tag 'drm-fixes-2024-04-09' of https://gitlab.freedesktop.org/drm/kernel:
  nouveau: fix devinit paths to only handle display on GSP.

Add a missing doublequote in the __is_constexpr() macro comment.
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

If the "bootconfig" kernel command-line argument was specified or if
the kernel was built with CONFIG_BOOT_CONFIG_FORCE, but if there are
no embedded kernel parameter, omit the "# Parameters from bootloader:"
comment from the /proc/bootconfig file.  This will cause automation
to fall back to the /proc/cmdline file, which will be identical to the
comment in this no-embedded-kernel-parameters case.

Link: https://lore.kernel.org/all/20240409044358.1156477-2-paulmck@kernel.org/

Fixes: 8b8ce6c75430 ("fs/proc: remove redundant comments from /proc/bootconfig")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: stable@vger.kernel.org
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

commit 717c7c89 ("fs/proc: Add boot loader arguments as comment to
/proc/bootconfig") adds bootloader argument comments into /proc/bootconfig.

/proc/bootconfig shows boot_command_line[] multiple times following
every xbc key value pair, that's duplicated and not necessary.
Remove redundant ones.

Output before and after the fix is like:
key1 = value1
*bootloader argument comments*
key2 = value2
*bootloader argument comments*
key3 = value3
*bootloader argument comments*
...

key1 = value1
key2 = value2
key3 = value3
*bootloader argument comments*
...

Link: https://lore.kernel.org/all/20240409044358.1156477-1-paulmck@kernel.org/

Fixes: 717c7c89 ("fs/proc: Add boot loader arguments as comment to /proc/bootconfig")
Signed-off-by: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: <linux-trace-kernel@vger.kernel.org>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: stable@vger.kernel.org
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

shoot down journal keys _before_ populating journal keys with pointers
to scanned nodes
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

This reverts:
nouveau/gsp: don't check devinit disable on GSP.
and applies a further fix.

It turns out the open gpu driver, checks this register,
but only for display.

Match that behaviour and in the turing path only disable
the display block. (ampere already only does displays).

Fixes: 5d4e8ae6 ("nouveau/gsp: don't check devinit disable on GSP.")
Reviewed-by: Danilo Krummrich <dakr@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240408064243.2219527-1-airlied@gmail.com

Pull x86 mitigations from Thomas Gleixner:
 "Mitigations for the native BHI hardware vulnerabilty:

  Branch History Injection (BHI) attacks may allow a malicious
  application to influence indirect branch prediction in kernel by
  poisoning the branch history. eIBRS isolates indirect branch targets
  in ring0. The BHB can still influence the choice of indirect branch
  predictor entry, and although branch predictor entries are isolated
  between modes when eIBRS is enabled, the BHB itself is not isolated
  between modes.

  Add mitigations against it either with the help of microcode or with
  software sequences for the affected CPUs"

[ This also ends up enabling the full mitigation by default despite the
  system call hardening, because apparently there are other indirect
  calls that are still sufficiently reachable, and the 'auto' case just
  isn't hardened enough.

  We'll have some more inevitable tweaking in the future    - Linus ]

* tag 'nativebhi' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  KVM: x86: Add BHI_NO
  x86/bhi: Mitigate KVM by default
  x86/bhi: Add BHI mitigation knob
  x86/bhi: Enumerate Branch History Injection (BHI) bug
  x86/bhi: Define SPEC_CTRL_BHI_DIS_S
  x86/bhi: Add support for clearing branch history at syscall entry
  x86/syscall: Don't force use of indirect calls for system calls
  x86/bugs: Change commas to semicolons in 'spectre_v2' sysfs file

- fix return types: promoting from unsigned to ssize_t does not do what
  we want here, and was pointless since the rest of the eytzinger code
  is u32
- nr, not size
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Pull btrfs fixes from David Sterba:
 "Several fixes to qgroups that have been recently identified by test
  generic/475:

   - fix prealloc reserve leak in subvolume operations

   - various other fixes in reservation setup, conversion or cleanup"

* tag 'for-6.9-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: always clear PERTRANS metadata during commit
  btrfs: make btrfs_clear_delalloc_extent() free delalloc reserve
  btrfs: qgroup: convert PREALLOC to PERTRANS after record_root_in_trans
  btrfs: record delayed inode root in transaction
  btrfs: qgroup: fix qgroup prealloc rsv leak in subvolume operations
  btrfs: qgroup: correctly model root qgroup rsv in convert

Intel processors that aren't vulnerable to BHI will set
MSR_IA32_ARCH_CAPABILITIES[BHI_NO] = 1;. Guests may use this BHI_NO bit to
determine if they need to implement BHI mitigations or not.  Allow this bit
to be passed to the guests.
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>

BHI mitigation mode spectre_bhi=auto does not deploy the software
mitigation by default. In a cloud environment, it is a likely scenario
where userspace is trusted but the guests are not trusted. Deploying
system wide mitigation in such cases is not desirable.

Update the auto mode to unconditionally mitigate against malicious
guests. Deploy the software sequence at VMexit in auto mode also, when
hardware mitigation is not available. Unlike the force =on mode,
software sequence is not deployed at syscalls in auto mode.
Suggested-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>

Branch history clearing software sequences and hardware control
BHI_DIS_S were defined to mitigate Branch History Injection (BHI).

Add cmdline spectre_bhi={on|off|auto} to control BHI mitigation:

 auto - Deploy the hardware mitigation BHI_DIS_S, if available.
 on   - Deploy the hardware mitigation BHI_DIS_S, if available,
        otherwise deploy the software sequence at syscall entry and
	VMexit.
 off  - Turn off BHI mitigation.

The default is auto mode which does not deploy the software sequence
mitigation.  This is because of the hardening done in the syscall
dispatch path, which is the likely target of BHI.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>

Mitigation for BHI is selected based on the bug enumeration. Add bits
needed to enumerate BHI bug.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>

Newer processors supports a hardware control BHI_DIS_S to mitigate
Branch History Injection (BHI). Setting BHI_DIS_S protects the kernel
from userspace BHI attacks without having to manually overwrite the
branch history.

Define MSR_SPEC_CTRL bit BHI_DIS_S and its enumeration CPUID.BHI_CTRL.
Mitigation is enabled later.
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>

Branch History Injection (BHI) attacks may allow a malicious application to
influence indirect branch prediction in kernel by poisoning the branch
history. eIBRS isolates indirect branch targets in ring0.  The BHB can
still influence the choice of indirect branch predictor entry, and although
branch predictor entries are isolated between modes when eIBRS is enabled,
the BHB itself is not isolated between modes.

Alder Lake and new processors supports a hardware control BHI_DIS_S to
mitigate BHI.  For older processors Intel has released a software sequence
to clear the branch history on parts that don't support BHI_DIS_S. Add
support to execute the software sequence at syscall entry and VMexit to
overwrite the branch history.

For now, branch history is not cleared at interrupt entry, as malicious
applications are not believed to have sufficient control over the
registers, since previous register state is cleared at interrupt
entry. Researchers continue to poke at this area and it may become
necessary to clear at interrupt entry as well in the future.

This mitigation is only defined here. It is enabled later.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Co-developed-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>