Implement optimized version of the tlb flushing routines for systems
using ASIDs. These are behind the use_asid_allocator static branch to
not affect existing systems not using ASIDs.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
[hch: rebased on top of previous cleanups, use the same algorithm as
      the non-ASID based code for local vs global flushes, keep functions
      as local as possible]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Move the call mm_cpumask from the callers into __sbi_tlb_flush_range to
reduce a bit of duplicate code and prepare for future changes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

The memblock_enforce_memory_limit() could change the memblock
range, so move the dram_end assignment after it in bootmem_init(),
then support mem= cmdline.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

The SWIOTLB buffer is not needed unless the physical address space
is beyond the limit of dma, only initialize swiotlb when swiotlb_force
is true or not all system memory is DMA-able.

Also move the swiotlb_init() into mem_init().
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Commit 01062356 introduced a typo in "__initdata" spelling
which led to build breakage for XIP. Fix that.

Fixes: 01062356 ("riscv: mm: init: Consolidate vars, functions")
Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

These functions haven't been used, so just remove them. The patch
has been tested with riscv.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Use better bitmap_zalloc() to allocate bitmap.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Fix build error when disable CONFIG_SMP:
mm/pgtable-generic.o: In function `.L19':
pgtable-generic.c:(.text+0x42): undefined reference to `flush_pmd_tlb_range'
mm/pgtable-generic.o: In function `pmdp_huge_clear_flush':
pgtable-generic.c:(.text+0x6c): undefined reference to `flush_pmd_tlb_range'
mm/pgtable-generic.o: In function `pmdp_invalidate':
pgtable-generic.c:(.text+0x162): undefined reference to `flush_pmd_tlb_range'

Fixes: e88b3331 ("riscv: mm: add THP support on 64-bit")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Bixuan Cui <cuibixuan@huawei.com>
Acked-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

We map kernel pages into all addresses spages, so they can be marked as
global.  This allows hardware to avoid flushing the kernel mappings when
moving between address spaces.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
[Palmer: commit text]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Fix a Kconfig warning and many build errors:

WARNING: unmet direct dependencies detected for COMPACTION
  Depends on [n]: MMU [=n]
  Selected by [y]:
  - TRANSPARENT_HUGEPAGE [=y] && HAVE_ARCH_TRANSPARENT_HUGEPAGE [=y]

and the subseqent thousands of build errors and warnings.

Fixes: e88b3331 ("riscv: mm: add THP support on 64-bit")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Consolidate the following items in init.c

Staticize global vars as much as possible;
Add __initdata mark if the global var isn't needed after init
Add __init mark if the func isn't needed after init
Add __ro_after_init if the global var is read only after init
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

These functions are not needed after booting, so mark them as __init
to move them to the __init section.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Inspired by commit ba090f9c ("arm64: kprobes: Remove redundant
kprobe_step_ctx"), the ss_pending and match_addr of kprobe_step_ctx
are redundant because those can be replaced by KPROBE_HIT_SS and
&cur_kprobe->ainsn.api.insn[0] + GET_INSN_LENGTH(cur->opcode)
respectively.

Remove the kprobe_step_ctx to simplify the code.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

The has_fpu check sits at hot code path: switch_to(). Currently, has_fpu
is a bool variable if FPU=y, switch_to() checks it each time, we can
optimize out this check by turning the has_fpu into a static key.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Directly passing the cpu to flush_icache_deferred() rather than calling
smp_processor_id() again.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
[Palmer: drop the QEMU performance numbers, and update the comment]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

The _sdata/_edata is already in sections.h, drop redundant
declaration.

Also move _xiprom/_exiprom declarations at the beginning of
the file, cleanup one CONFIG_XIP_KERNEL.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Make setup_bootmem() static.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Enable the PCI resource mapping on RISC-V using the generic framework.
This allows userspace applications to mmap PCI resources using
/sys/devices/pci*/*/resource* interface.
The mmap has been tested with Intel x520-DA2 NIC card on a HiFive
Unmatched board (SiFive FU740 SoC).
Signed-off-by: Stanislaw Kardach <kda@semihalf.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

The empty_zero_page sits at .bss..page_aligned section, so will be
cleared to zero during clearing bss, we don't need to clear it again.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

HAVE_MOVE_PUD enables remapping pages at the PUD level if both the source
and destination addresses are PUD-aligned.
HAVE_MOVE_PMD does similar speedup on the PMD level.

With HAVE_MOVE_PUD enabled, there is about a 143x improvement on qemu
With HAVE_MOVE_PMD enabled, there is about a 5x improvement on qemu
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Bring Transparent HugePage support to riscv. A
transparent huge page is always represented as a pmd.
Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Add a parameter: stride for __sbi_tlb_flush_range(),
represent the page stride between the address of start and end.
Normally, the stride is PAGE_SIZE, and when flush huge page
address, the stride can be the huge page size such as:PMD_SIZE,
then it only need to flush one tlb entry if the address range
within PMD_SIZE.
Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

In the definition in Documentation/vm/arch_pgtable_helpers.rst,
pmd_bad() means test a non-table mapped PMD, so it should also
return true when it is a leaf page.
Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

In riscv, a page table entry is leaf when any bit of read, write,
or execute bit is set. So add a macro:_PAGE_LEAF instead of
(_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC), which is frequently used
to determine if it is a leaf page. This make code easier to read,
without any functional change.
Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Commit b9d79e4c ("fbmem: Mark proc_fb_seq_ops as __maybe_unused")
places the '__maybe_unused' in an entirely incorrect location between
the "struct" keyword and the structure name.

It's a wonder that gcc accepts that silently, but clang quite reasonably
warns about it:

    drivers/video/fbdev/core/fbmem.c:736:21: warning: attribute declaration must precede definition [-Wignored-attributes]
    static const struct __maybe_unused seq_operations proc_fb_seq_ops = {
                        ^

Fix it.

Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull drm fixes from Dave Airlie:
 "Bit later than usual, I queued them all up on Friday then promptly
  forgot to write the pull request email. This is mainly amdgpu fixes,
  with some radeon/msm/fbdev and one i915 gvt fix thrown in.

  amdgpu:
   - MPO hang workaround
   - Fix for concurrent VM flushes on vega/navi
   - dcefclk is not adjustable on navi1x and newer
   - MST HPD debugfs fix
   - Suspend/resumes fixes
   - Register VGA clients late in case driver fails to load
   - Fix GEM leak in user framebuffer create
   - Add support for polaris12 with 32 bit memory interface
   - Fix duplicate cursor issue when using overlay
   - Fix corruption with tiled surfaces on VCN3
   - Add BO size and stride check to fix BO size verification

  radeon:
   - Fix off-by-one in power state parsing
   - Fix possible memory leak in power state parsing

  msm:
   - NULL ptr dereference fix

  fbdev:
   - procfs disabled warning fix

  i915:
   - gvt: Fix a possible division by zero in vgpu display rate
     calculation"

* tag 'drm-next-2021-05-10' of git://anongit.freedesktop.org/drm/drm:
  drm/amdgpu: Use device specific BO size & stride check.
  drm/amdgpu: Init GFX10_ADDR_CONFIG for VCN v3 in DPG mode.
  drm/amd/pm: initialize variable
  drm/radeon: Avoid power table parsing memory leaks
  drm/radeon: Fix off-by-one power_state index heap overwrite
  drm/amd/display: Fix two cursor duplication when using overlay
  drm/amdgpu: add new MC firmware for Polaris12 32bit ASIC
  fbmem: Mark proc_fb_seq_ops as __maybe_unused
  drm/msm/dpu: Delete bonkers code
  drm/i915/gvt: Prevent divided by zero when calculating refresh rate
  amdgpu: fix GEM obj leak in amdgpu_display_user_framebuffer_create
  drm/amdgpu: Register VGA clients after init can no longer fail
  drm/amdgpu: Handling of amdgpu_device_resume return value for graceful teardown
  drm/amdgpu: fix r initial values
  drm/amd/display: fix wrong statement in mst hpd debugfs
  amdgpu/pm: set pp_dpm_dcefclk to readonly on NAVI10 and newer gpus
  amdgpu/pm: Prevent force of DCEFCLK on NAVI10 and SIENNA_CICHLID
  drm/amdgpu: fix concurrent VM flushes on Vega/Navi v2
  drm/amd/display: Reject non-zero src_y and src_x for video planes

Pull block fix from Jens Axboe:
 "Turns out the bio max size change still has issues, so let's get it
  reverted for 5.13-rc1. We'll shake out the issues there and defer it
  to 5.14 instead"

* tag 'block-5.13-2021-05-09' of git://git.kernel.dk/linux-block:
  Revert "bio: limit bio max size"

Pull cifs fixes from Steve French:
 "Three small SMB3 chmultichannel related changesets (also for stable)
  from the SMB3 test event this week.

  The other fixes are still in review/testing"

* tag '5.13-rc-smb3-part3' of git://git.samba.org/sfrench/cifs-2.6:
  smb3: if max_channels set to more than one channel request multichannel
  smb3: do not attempt multichannel to server which does not support it
  smb3: when mounting with multichannel include it in requested capabilities

Pull scheduler fixes from Thomas Gleixner:
 "A set of scheduler updates:

   - Prevent PSI state corruption when schedule() races with cgroup
     move.

     A recent commit combined two PSI callbacks to reduce the number of
     cgroup tree updates, but missed that schedule() can drop rq::lock
     for load balancing, which opens the race window for
     cgroup_move_task() which then observes half updated state.

     The fix is to solely use task::ps_flags instead of looking at the
     potentially mismatching scheduler state

   - Prevent an out-of-bounds access in uclamp caused bu a rounding
     division which can lead to an off-by-one error exceeding the
     buckets array size.

   - Prevent unfairness caused by missing load decay when a task is
     attached to a cfs runqueue.

     The old load of the task was attached to the runqueue and never
     removed. Fix it by enforcing the load update through the hierarchy
     for unthrottled run queue instances.

   - A documentation fix fot the 'sched_verbose' command line option"

* tag 'sched-urgent-2021-05-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Fix unfairness caused by missing load decay
  sched: Fix out-of-bound access in uclamp
  psi: Fix psi state corruption when schedule() races with cgroup move
  sched,doc: sched_debug_verbose cmdline should be sched_verbose

Pull locking fixes from Thomas Gleixner:
 "A set of locking related fixes and updates:

   - Two fixes for the futex syscall related to the timeout handling.

     FUTEX_LOCK_PI does not support the FUTEX_CLOCK_REALTIME bit and
     because it's not set the time namespace adjustment for clock
     MONOTONIC is applied wrongly.

     FUTEX_WAIT cannot support the FUTEX_CLOCK_REALTIME bit because its
     always a relative timeout.

   - Cleanups in the futex syscall entry points which became obvious
     when the two timeout handling bugs were fixed.

   - Cleanup of queued_write_lock_slowpath() as suggested by Linus

   - Fixup of the smp_call_function_single_async() prototype"

* tag 'locking-urgent-2021-05-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Make syscall entry points less convoluted
  futex: Get rid of the val2 conditional dance
  futex: Do not apply time namespace adjustment on FUTEX_LOCK_PI
  Revert 337f1304 ("futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op")
  locking/qrwlock: Cleanup queued_write_lock_slowpath()
  smp: Fix smp_call_function_single_async prototype

Pull x86 perf fix from Borislav Petkov:
 "Handle power-gating of AMD IOMMU perf counters properly when they are
  used"

* tag 'perf_urgent_for_v5.13_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/events/amd/iommu: Fix invalid Perf result due to IOMMU PMC power-gating

Pull x86 fixes from Borislav Petkov:
 "A bunch of things accumulated for x86 in the last two weeks:

   - Fix guest vtime accounting so that ticks happening while the guest
     is running can also be accounted to it. Along with a consolidation
     to the guest-specific context tracking helpers.

   - Provide for the host NMI handler running after a VMX VMEXIT to be
     able to run on the kernel stack correctly.

   - Initialize MSR_TSC_AUX when RDPID is supported and not RDTSCP (virt
     relevant - real hw supports both)

   - A code generation improvement to TASK_SIZE_MAX through the use of
     alternatives

   - The usual misc and related cleanups and improvements"

* tag 'x86_urgent_for_v5.13_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  KVM: x86: Consolidate guest enter/exit logic to common helpers
  context_tracking: KVM: Move guest enter/exit wrappers to KVM's domain
  context_tracking: Consolidate guest enter/exit wrappers
  sched/vtime: Move guest enter/exit vtime accounting to vtime.h
  sched/vtime: Move vtime accounting external declarations above inlines
  KVM: x86: Defer vtime accounting 'til after IRQ handling
  context_tracking: Move guest exit vtime accounting to separate helpers
  context_tracking: Move guest exit context tracking to separate helpers
  KVM/VMX: Invoke NMI non-IST entry instead of IST entry
  x86/cpu: Remove write_tsc() and write_rdtscp_aux() wrappers
  x86/cpu: Initialize MSR_TSC_AUX if RDTSCP *or* RDPID is supported
  x86/resctrl: Fix init const confusion
  x86: Delete UD0, UD1 traces
  x86/smpboot: Remove duplicate includes
  x86/cpu: Use alternative to generate the TASK_SIZE_MAX constant

This reverts commit cd2c7545.

Alex reports that the commit causes corruption with LUKS on ext4. Revert
it for now so that this can be investigated properly.

Link: https://lore.kernel.org/linux-block/1620493841.bxdq8r5haw.none@localhost/Reported-by: Alex Xu (Hello71) <alex_y_xu@yahoo.ca>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull RISC-V fixes from Palmer Dabbelt:

 - A fix to avoid over-allocating the kernel's mapping on !MMU systems,
   which could lead to up to 2MiB of lost memory

 - The SiFive address extension errata only manifest on rv64, they are
   now disabled on rv32 where they are unnecessary

 - A pair of late-landing cleanups

* tag 'riscv-for-linus-5.13-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: remove unused handle_exception symbol
  riscv: Consistify protect_kernel_linear_mapping_text_rodata() use
  riscv: enable SiFive errata CIP-453 and CIP-1200 Kconfig only if CONFIG_64BIT=y
  riscv: Only extend kernel reservation if mapped read-only

intel_dp_check_mst_status() uses a 14-byte array to read the DPRX Event
Status Indicator data, but then passes that buffer at offset 10 off as
an argument to drm_dp_channel_eq_ok().

End result: there are only 4 bytes remaining of the buffer, yet
drm_dp_channel_eq_ok() wants a 6-byte buffer.  gcc-11 correctly warns
about this case:

  drivers/gpu/drm/i915/display/intel_dp.c: In function ‘intel_dp_check_mst_status’:
  drivers/gpu/drm/i915/display/intel_dp.c:3491:22: warning: ‘drm_dp_channel_eq_ok’ reading 6 bytes from a region of size 4 [-Wstringop-overread]
   3491 |                     !drm_dp_channel_eq_ok(&esi[10], intel_dp->lane_count)) {
        |                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  drivers/gpu/drm/i915/display/intel_dp.c:3491:22: note: referencing argument 1 of type ‘const u8 *’ {aka ‘const unsigned char *’}
  In file included from drivers/gpu/drm/i915/display/intel_dp.c:38:
  include/drm/drm_dp_helper.h:1466:6: note: in a call to function ‘drm_dp_channel_eq_ok’
   1466 | bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
        |      ^~~~~~~~~~~~~~~~~~~~
       6:14 elapsed

This commit just extends the original array by 2 zero-initialized bytes,
avoiding the warning.

There may be some underlying bug in here that caused this confusion, but
this is at least no worse than the existing situation that could use
random data off the stack.

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull more SCSI updates from James Bottomley:
 "This is a set of minor fixes in various drivers (qla2xxx, ufs,
  scsi_debug, lpfc) one doc fix and a fairly large update to the fnic
  driver to remove the open coded iteration functions in favour of the
  scsi provided ones"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: fnic: Use scsi_host_busy_iter() to traverse commands
  scsi: fnic: Kill 'exclude_id' argument to fnic_cleanup_io()
  scsi: scsi_debug: Fix cmd_per_lun, set to max_queue
  scsi: ufs: core: Narrow down fast path in system suspend path
  scsi: ufs: core: Cancel rpm_dev_flush_recheck_work during system suspend
  scsi: ufs: core: Do not put UFS power into LPM if link is broken
  scsi: qla2xxx: Prevent PRLI in target mode
  scsi: qla2xxx: Add marginal path handling support
  scsi: target: tcmu: Return from tcmu_handle_completions() if cmd_id not found
  scsi: ufs: core: Fix a typo in ufs-sysfs.c
  scsi: lpfc: Fix bad memory access during VPD DUMP mailbox command
  scsi: lpfc: Fix DMA virtual address ptr assignment in bsg
  scsi: lpfc: Fix illegal memory access on Abort IOCBs
  scsi: blk-mq: Fix build warning when making htmldocs

Pull more Kbuild updates from Masahiro Yamada:

 - Convert sh and sparc to use generic shell scripts to generate the
   syscall headers

 - refactor .gitignore files

 - Update kernel/config_data.gz only when the content of the .config
   is really changed, which avoids the unneeded re-link of vmlinux

 - move "remove stale files" workarounds to scripts/remove-stale-files

 - suppress unused-but-set-variable warnings by default for Clang
   as well

 - fix locale setting LANG=C to LC_ALL=C

 - improve 'make distclean'

 - always keep intermediate objects from scripts/link-vmlinux.sh

 - move IF_ENABLED out of <linux/kconfig.h> to make it self-contained

 - misc cleanups

* tag 'kbuild-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (25 commits)
  linux/kconfig.h: replace IF_ENABLED() with PTR_IF() in <linux/kernel.h>
  kbuild: Don't remove link-vmlinux temporary files on exit/signal
  kbuild: remove the unneeded comments for external module builds
  kbuild: make distclean remove tag files in sub-directories
  kbuild: make distclean work against $(objtree) instead of $(srctree)
  kbuild: refactor modname-multi by using suffix-search
  kbuild: refactor fdtoverlay rule
  kbuild: parameterize the .o part of suffix-search
  arch: use cross_compiling to check whether it is a cross build or not
  kbuild: remove ARCH=sh64 support from top Makefile
  .gitignore: prefix local generated files with a slash
  kbuild: replace LANG=C with LC_ALL=C
  Makefile: Move -Wno-unused-but-set-variable out of GCC only block
  kbuild: add a script to remove stale generated files
  kbuild: update config_data.gz only when the content of .config is changed
  .gitignore: ignore only top-level modules.builtin
  .gitignore: move tags and TAGS close to other tag files
  kernel/.gitgnore: remove stale timeconst.h and hz.bc
  usr/include: refactor .gitignore
  genksyms: fix stale comment
  ...

Mounting with "multichannel" is obviously implied if user requested
more than one channel on mount (ie mount parm max_channels>1).
Currently both have to be specified. Fix that so that if max_channels
is greater than 1 on mount, enable multichannel rather than silently
falling back to non-multichannel.
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-By: Tom Talpey <tom@talpey.com>
Cc: <stable@vger.kernel.org> # v5.11+
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>

We were ignoring CAP_MULTI_CHANNEL in the server response - if the
server doesn't support multichannel we should not be attempting it.

See MS-SMB2 section 3.2.5.2
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-By: Tom Talpey <tom@talpey.com>
Cc: <stable@vger.kernel.org> # v5.8+
Signed-off-by: Steve French <stfrench@microsoft.com>