We generally want to disallow hypercall bitmaps being changed
once vcpus have already run. But we must allow the write if
the written value is unchanged so that userspace can rewrite
the register file on reboot, for example.

Without this, a QEMU-based VM will fail to reboot correctly.

The original code was correct, and it is me that introduced
the regression.

Fixes: 05714cab ("KVM: arm64: Setup a framework for hypercall bitmap firmware registers")
Signed-off-by: Marc Zyngier <maz@kernel.org>

These constants will change over time, and userspace has no
business knowing about them. Hide them behind __KERNEL__.
Signed-off-by: Marc Zyngier <maz@kernel.org>

Fix the TOC in index.rst after psci.rst has been renamed to
hypercalls.rst.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/r/20220504205627.18f46380@canb.auug.org.au

Add the psuedo-firmware registers KVM_REG_ARM_STD_BMAP,
KVM_REG_ARM_STD_HYP_BMAP, and KVM_REG_ARM_VENDOR_HYP_BMAP to
the base_regs[] list.

Also, add the COPROC support for KVM_REG_ARM_FW_FEAT_BMAP.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220502233853.1233742-10-rananta@google.com

Introduce a KVM selftest to check the hypercall interface
for arm64 platforms. The test validates the user-space'
[GET|SET]_ONE_REG interface to read/write the psuedo-firmware
registers as well as its effects on the guest upon certain
configurations.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220502233853.1233742-9-rananta@google.com

The PSCI and PV stolen time tests both need to make SMCCC calls within
the guest. Create a helper for making SMCCC calls and rework the
existing tests to use the library function.
Signed-off-by: Oliver Upton <oupton@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220409184549.1681189-11-oupton@google.com

There are other interactions with PSCI worth testing; rename the PSCI
test to make it more generic.

No functional change intended.
Signed-off-by: Oliver Upton <oupton@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220409184549.1681189-10-oupton@google.com

Import the standard SMCCC definitions from include/linux/arm-smccc.h.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220502233853.1233742-8-rananta@google.com

Add the documentation for the bitmap firmware registers in
hypercalls.rst and api.rst. This includes the details for
KVM_REG_ARM_STD_BMAP, KVM_REG_ARM_STD_HYP_BMAP, and
KVM_REG_ARM_VENDOR_HYP_BMAP registers.

Since the document is growing to carry other hypercall related
information, make necessary adjustments to present the document
in a generic sense, rather than being PSCI focused.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
[maz: small scale reformat, move things about, random typo fixes]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220502233853.1233742-7-rananta@google.com

Since the doc also covers general hypercalls' details,
rather than just PSCI, and the fact that the bitmap firmware
registers' details will be added to this doc, rename the file
to a more appropriate name- hypercalls.rst.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220502233853.1233742-6-rananta@google.com

Introduce the firmware register to hold the vendor specific
hypervisor service calls (owner value 6) as a bitmap. The
bitmap represents the features that'll be enabled for the
guest, as configured by the user-space. Currently, this
includes support for KVM-vendor features along with
reading the UID, represented by bit-0, and Precision Time
Protocol (PTP), represented by bit-1.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
[maz: tidy-up bitmap values]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220502233853.1233742-5-rananta@google.com

Introduce the firmware register to hold the standard hypervisor
service calls (owner value 5) as a bitmap. The bitmap represents
the features that'll be enabled for the guest, as configured by
the user-space. Currently, this includes support only for
Paravirtualized time, represented by bit-0.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
[maz: tidy-up bitmap values]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220502233853.1233742-4-rananta@google.com

KVM regularly introduces new hypercall services to the guests without
any consent from the userspace. This means, the guests can observe
hypercall services in and out as they migrate across various host
kernel versions. This could be a major problem if the guest
discovered a hypercall, started using it, and after getting migrated
to an older kernel realizes that it's no longer available. Depending
on how the guest handles the change, there's a potential chance that
the guest would just panic.

As a result, there's a need for the userspace to elect the services
that it wishes the guest to discover. It can elect these services
based on the kernels spread across its (migration) fleet. To remedy
this, extend the existing firmware pseudo-registers, such as
KVM_REG_ARM_PSCI_VERSION, but by creating a new COPROC register space
for all the hypercall services available.

These firmware registers are categorized based on the service call
owners, but unlike the existing firmware pseudo-registers, they hold
the features supported in the form of a bitmap.

During the VM initialization, the registers are set to upper-limit of
the features supported by the corresponding registers. It's expected
that the VMMs discover the features provided by each register via
GET_ONE_REG, and write back the desired values using SET_ONE_REG.
KVM allows this modification only until the VM has started.

Some of the standard features are not mapped to any bits of the
registers. But since they can recreate the original problem of
making it available without userspace's consent, they need to
be explicitly added to the case-list in
kvm_hvc_call_default_allowed(). Any function-id that's not enabled
via the bitmap, or not listed in kvm_hvc_call_default_allowed, will
be returned as SMCCC_RET_NOT_SUPPORTED to the guest.

Older userspace code can simply ignore the feature and the
hypercall services will be exposed unconditionally to the guests,
thus ensuring backward compatibility.

In this patch, the framework adds the register only for ARM's standard
secure services (owner value 4). Currently, this includes support only
for ARM True Random Number Generator (TRNG) service, with bit-0 of the
register representing mandatory features of v1.0. Other services are
momentarily added in the upcoming patches.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
[maz: reduced the scope of some helpers, tidy-up bitmap max values,
 dropped error-only fast path]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220502233853.1233742-3-rananta@google.com

Common hypercall firmware register handing is currently employed
by psci.c. Since the upcoming patches add more of these registers,
it's better to move the generic handling to hypercall.c for a
cleaner presentation.

While we are at it, collect all the firmware registers under
fw_reg_ids[] to help implement kvm_arm_get_fw_num_regs() and
kvm_arm_copy_fw_reg_indices() in a generic way. Also, define
KVM_REG_FEATURE_LEVEL_MASK using a GENMASK instead.

No functional change intended.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
[maz: fixed KVM_REG_FEATURE_LEVEL_MASK]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220502233853.1233742-2-rananta@google.com

Pull xen fixlet from Juergen Gross:
 "A single cleanup patch for the Xen balloon driver"

* tag 'for-linus-5.18-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/balloon: don't use PV mode extra memory for zone device allocations

Pull x86 fixes from Thomas Gleixner:
 "Two x86 fixes related to TSX:

   - Use either MSR_TSX_FORCE_ABORT or MSR_IA32_TSX_CTRL to disable TSX
     to cover all CPUs which allow to disable it.

   - Disable TSX development mode at boot so that a microcode update
     which provides TSX development mode does not suddenly make the
     system vulnerable to TSX Asynchronous Abort"

* tag 'x86-urgent-2022-04-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/tsx: Disable TSX development mode at boot
  x86/tsx: Use MSR_TSX_CTRL to clear CPUID bits

Pull timer fixes from Thomas Gleixner:
 "A small set of fixes for the timers core:

   - Fix the warning condition in __run_timers() which does not take
     into account that a CPU base (especially the deferrable base) never
     has a timer armed on it and therefore the next_expiry value can
     become stale.

   - Replace a WARN_ON() in the NOHZ code with a WARN_ON_ONCE() to
     prevent endless spam in dmesg.

   - Remove the double star from a comment which is not meant to be in
     kernel-doc format"

* tag 'timers-urgent-2022-04-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tick/sched: Fix non-kernel-doc comment
  tick/nohz: Use WARN_ON_ONCE() to prevent console saturation
  timers: Fix warning condition in __run_timers()

Pull SMP fixes from Thomas Gleixner:
 "Two fixes for the SMP core:

   - Make the warning condition in flush_smp_call_function_queue()
     correct, which checked a just emptied list head for being empty
     instead of validating that there was no pending entry on the
     offlined CPU at all.

   - The @cpu member of struct cpuhp_cpu_state is initialized when the
     CPU hotplug thread for the upcoming CPU is created. That's too late
     because the creation of the thread can fail and then the following
     rollback operates on CPU0. Get rid of the CPU member and hand the
     CPU number to the involved functions directly"

* tag 'smp-urgent-2022-04-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cpu/hotplug: Remove the 'cpu' member of cpuhp_cpu_state
  smp: Fix offline cpu check in flush_smp_call_function_queue()

Pull irq fix from Thomas Gleixner:
 "A single fix for the interrupt affinity spreading logic to take into
  account that there can be an imbalance between present and possible
  CPUs, which causes already assigned bits to be overwritten"

* tag 'irq-urgent-2022-04-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq/affinity: Consider that CPUs on nodes can be unbalanced

Pull power supply fixes from Sebastian Reichel:

 - Fix a regression with battery data failing to load from DT

* tag 'for-v5.18-rc' of git://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-power-supply:
  power: supply: Reset err after not finding static battery
  power: supply: samsung-sdi-battery: Add missing charge restart voltages

Pull i2c fixes from Wolfram Sang:
 "Regular set of fixes for drivers and the dev-interface"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: ismt: Fix undefined behavior due to shift overflowing the constant
  i2c: dev: Force case user pointers in compat_i2cdev_ioctl()
  i2c: dev: check return value when calling dev_set_name()
  i2c: qcom-geni: Use dev_err_probe() for GPI DMA error
  i2c: imx: Implement errata ERR007805 or e7805 bus frequency limit
  i2c: pasemi: Wait for write xfers to finish

Pull devicetree fixes from Rob Herring:

 - Fix scalar property schemas with array constraints

 - Fix 'enum' lists with duplicate entries

 - Fix incomplete if/then/else schemas

 - Add Renesas RZ/V2L SoC support to Mali Bifrost binding

 - Maintainers update for Marvell irqchip

* tag 'devicetree-fixes-for-5.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
  dt-bindings: display: panel-timing: Define a single type for properties
  dt-bindings: Fix array constraints on scalar properties
  dt-bindings: gpu: mali-bifrost: Document RZ/V2L SoC
  dt-bindings: net: snps: remove duplicate name
  dt-bindings: Fix 'enum' lists with duplicate entries
  dt-bindings: irqchip: mrvl,intc: refresh maintainers
  dt-bindings: Fix incomplete if/then/else schemas
  dt-bindings: power: renesas,apmu: Fix cpus property limits
  dt-bindings: extcon: maxim,max77843: fix ports type

Pull gpio fixes from Bartosz Golaszewski:
 "A single fix for gpio-sim and two patches for GPIO ACPI pulled from
  Andy:

   - fix the set/get_multiple() callbacks in gpio-sim

   - use correct format characters in gpiolib-acpi

   - use an unsigned type for pins in gpiolib-acpi"

* tag 'gpio-fixes-for-v5.18-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux:
  gpio: sim: fix setting and getting multiple lines
  gpiolib: acpi: Convert type for pin to be unsigned
  gpiolib: acpi: use correct format characters

Pull ARM SoC fixes from Arnd Bergmann:
 "There are a number of SoC bugfixes that came in since the merge
  window, and more of them are already pending.

  This batch includes:

   - A boot time regression fix for davinci that triggered on
     multi_v5_defconfig when booting any platform

   - Defconfig updates to address removed features, changed symbol names
     or dependencies, for gemini, ux500, and pxa

   - Email address changes for Krzysztof Kozlowski

   - Build warning fixes for ep93xx and iop32x

   - Devicetree warning fixes across many platforms

   - Minor bugfixes for the reset controller, memory controller and SCMI
     firmware subsystems plus the versatile-express board"

* tag 'soc-fixes-5.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (34 commits)
  ARM: config: Update Gemini defconfig
  arm64: dts: qcom/sdm845-shift-axolotl: Fix boolean properties with values
  ARM: dts: align SPI NOR node name with dtschema
  ARM: dts: Fix more boolean properties with values
  arm/arm64: dts: qcom: Fix boolean properties with values
  arm64: dts: imx: Fix imx8*-var-som touchscreen property sizes
  arm: dts: imx: Fix boolean properties with values
  arm64: dts: tegra: Fix boolean properties with values
  arm: dts: at91: Fix boolean properties with values
  arm: configs: imote2: Drop defconfig as board support dropped.
  ep93xx: clock: Don't use plain integer as NULL pointer
  ep93xx: clock: Fix UAF in ep93xx_clk_register_gate()
  ARM: vexpress/spc: Fix all the kernel-doc build warnings
  ARM: vexpress/spc: Fix kernel-doc build warning for ve_spc_cpu_in_wfi
  ARM: config: u8500: Re-enable AB8500 battery charging
  ARM: config: u8500: Add some common hardware
  memory: fsl_ifc: populate child nodes of buses and mfd devices
  ARM: config: Refresh U8500 defconfig
  firmware: arm_scmi: Fix sparse warnings in OPTEE transport driver
  firmware: arm_scmi: Replace zero-length array with flexible-array member
  ...

Pull random number generator fixes from Jason Donenfeld:

 - Per your suggestion, random reads now won't fail if there's a page
   fault after some non-zero amount of data has been read, which makes
   the behavior consistent with all other reads in the kernel.

 - Rather than an inconsistent mix of random_get_entropy() returning an
   unsigned long or a cycles_t, now it just returns an unsigned long.

 - A memcpy() was replaced with an memmove(), because the addresses are
   sometimes overlapping. In practice the destination is always before
   the source, so not really an issue, but better to be correct than
   not.

* tag 'random-5.18-rc3-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
  random: use memmove instead of memcpy for remaining 32 bytes
  random: make random_get_entropy() return an unsigned long
  random: allow partial reads if later user copies fail

Pull SCSI fixes from James Bottomley:
 "13 fixes, all in drivers.

  The most extensive changes are in the iscsi series (affecting drivers
  qedi, cxgbi and bnx2i), the next most is scsi_debug, but that's just a
  simple revert and then minor updates to pm80xx"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: iscsi: MAINTAINERS: Add Mike Christie as co-maintainer
  scsi: qedi: Fix failed disconnect handling
  scsi: iscsi: Fix NOP handling during conn recovery
  scsi: iscsi: Merge suspend fields
  scsi: iscsi: Fix unbound endpoint error handling
  scsi: iscsi: Fix conn cleanup and stop race during iscsid restart
  scsi: iscsi: Fix endpoint reuse regression
  scsi: iscsi: Release endpoint ID when its freed
  scsi: iscsi: Fix offload conn cleanup when iscsid restarts
  scsi: iscsi: Move iscsi_ep_disconnect()
  scsi: pm80xx: Enable upper inbound, outbound queues
  scsi: pm80xx: Mask and unmask upper interrupt vectors 32-63
  Revert "scsi: scsi_debug: Address races following module load"

Merge tag 'intel-gpio-v5.18-2' of gitolite.kernel.org:pub/scm/linux/kernel/git/andy/linux-gpio-intel into gpio/for-current

intel-gpio for v5.18-2

* Couple of fixes related to handling unsigned value of the pin from ACPI

gpiolib:
 -  acpi: Convert type for pin to be unsigned
 -  acpi: use correct format characters

Pull dma-mapping fix from Christoph Hellwig:

 - avoid a double memory copy for swiotlb (Chao Gao)

* tag 'dma-mapping-5.18-2' of git://git.infradead.org/users/hch/dma-mapping:
  dma-direct: avoid redundant memory sync for swiotlb

In order to immediately overwrite the old key on the stack, before
servicing a userspace request for bytes, we use the remaining 32 bytes
of block 0 as the key. This means moving indices 8,9,a,b,c,d,e,f ->
4,5,6,7,8,9,a,b. Since 4 < 8, for the kernel implementations of
memcpy(), this doesn't actually appear to be a problem in practice. But
relying on that characteristic seems a bit brittle. So let's change that
to a proper memmove(), which is the by-the-books way of handling
overlapping memory copies.
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Merge misc fixes from Andrew Morton:
 "14 patches.

  Subsystems affected by this patch series: MAINTAINERS, binfmt, and
  mm (tmpfs, secretmem, kasan, kfence, pagealloc, zram, compaction,
  hugetlb, vmalloc, and kmemleak)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm: kmemleak: take a full lowmem check in kmemleak_*_phys()
  mm/vmalloc: fix spinning drain_vmap_work after reading from /proc/vmcore
  revert "fs/binfmt_elf: use PT_LOAD p_align values for static PIE"
  revert "fs/binfmt_elf: fix PT_LOAD p_align values for loaders"
  hugetlb: do not demote poisoned hugetlb pages
  mm: compaction: fix compiler warning when CONFIG_COMPACTION=n
  mm: fix unexpected zeroed page mapping with zram swap
  mm, page_alloc: fix build_zonerefs_node()
  mm, kfence: support kmem_dump_obj() for KFENCE objects
  kasan: fix hw tags enablement when KUNIT tests are disabled
  irq_work: use kasan_record_aux_stack_noalloc() record callstack
  mm/secretmem: fix panic when growing a memfd_secret
  tmpfs: fix regressions from wider use of ZERO_PAGE
  MAINTAINERS: Broadcom internal lists aren't maintainers

Merge tag 'for-5.18/dm-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper fixes from Mike Snitzer:

 - Fix memory corruption in DM integrity target when tag_size is less
   than digest size.

 - Fix DM multipath's historical-service-time path selector to not use
   sched_clock() and ktime_get_ns(); only use ktime_get_ns().

 - Fix dm_io->orig_bio NULL pointer dereference in dm_zone_map_bio() due
   to 5.18 changes that overlooked DM zone's use of ->orig_bio

 - Fix for regression that broke the use of dm_accept_partial_bio() for
   "abnormal" IO (e.g. WRITE ZEROES) that does not need duplicate bios

 - Fix DM's issuing of empty flush bio so that it's size is 0.

* tag 'for-5.18/dm-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm: fix bio length of empty flush
  dm: allow dm_accept_partial_bio() for dm_io without duplicate bios
  dm zone: fix NULL pointer dereference in dm_zone_map_bio
  dm mpath: only use ktime_get_ns() in historical selector
  dm integrity: fix memory corruption when tag_size is less than digest size

The kmemleak_*_phys() apis do not check the address for lowmem's min
boundary, while the caller may pass an address below lowmem, which will
trigger an oops:

  # echo scan > /sys/kernel/debug/kmemleak
  Unable to handle kernel paging request at virtual address ff5fffffffe00000
  Oops [#1]
  Modules linked in:
  CPU: 2 PID: 134 Comm: bash Not tainted 5.18.0-rc1-next-20220407 #33
  Hardware name: riscv-virtio,qemu (DT)
  epc : scan_block+0x74/0x15c
   ra : scan_block+0x72/0x15c
  epc : ffffffff801e5806 ra : ffffffff801e5804 sp : ff200000104abc30
   gp : ffffffff815cd4e8 tp : ff60000004cfa340 t0 : 0000000000000200
   t1 : 00aaaaaac23954cc t2 : 00000000000003ff s0 : ff200000104abc90
   s1 : ffffffff81b0ff28 a0 : 0000000000000000 a1 : ff5fffffffe01000
   a2 : ffffffff81b0ff28 a3 : 0000000000000002 a4 : 0000000000000001
   a5 : 0000000000000000 a6 : ff200000104abd7c a7 : 0000000000000005
   s2 : ff5fffffffe00ff9 s3 : ffffffff815cd998 s4 : ffffffff815d0e90
   s5 : ffffffff81b0ff28 s6 : 0000000000000020 s7 : ffffffff815d0eb0
   s8 : ffffffffffffffff s9 : ff5fffffffe00000 s10: ff5fffffffe01000
   s11: 0000000000000022 t3 : 00ffffffaa17db4c t4 : 000000000000000f
   t5 : 0000000000000001 t6 : 0000000000000000
  status: 0000000000000100 badaddr: ff5fffffffe00000 cause: 000000000000000d
    scan_gray_list+0x12e/0x1a6
    kmemleak_scan+0x2aa/0x57e
    kmemleak_write+0x32a/0x40c
    full_proxy_write+0x56/0x82
    vfs_write+0xa6/0x2a6
    ksys_write+0x6c/0xe2
    sys_write+0x22/0x2a
    ret_from_syscall+0x0/0x2

The callers may not quite know the actual address they pass(e.g. from
devicetree).  So the kmemleak_*_phys() apis should guarantee the address
they finally use is in lowmem range, so check the address for lowmem's
min boundary.

Link: https://lkml.kernel.org/r/20220413122925.33856-1-patrick.wang.shcn@gmail.comSigned-off-by: Patrick Wang <patrick.wang.shcn@gmail.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 3ee48b6a ("mm, x86: Saving vmcore with non-lazy freeing of
vmas") introduced set_iounmap_nonlazy(), which sets vmap_lazy_nr to
lazy_max_pages() + 1, ensuring that any future vunmaps() immediately
purge the vmap areas instead of doing it lazily.

Commit 690467c8 ("mm/vmalloc: Move draining areas out of caller
context") moved the purging from the vunmap() caller to a worker thread.
Unfortunately, set_iounmap_nonlazy() can cause the worker thread to spin
(possibly forever).  For example, consider the following scenario:

 1. Thread reads from /proc/vmcore. This eventually calls
    __copy_oldmem_page() -> set_iounmap_nonlazy(), which sets
    vmap_lazy_nr to lazy_max_pages() + 1.

 2. Then it calls free_vmap_area_noflush() (via iounmap()), which adds 2
    pages (one page plus the guard page) to the purge list and
    vmap_lazy_nr. vmap_lazy_nr is now lazy_max_pages() + 3, so the
    drain_vmap_work is scheduled.

 3. Thread returns from the kernel and is scheduled out.

 4. Worker thread is scheduled in and calls drain_vmap_area_work(). It
    frees the 2 pages on the purge list. vmap_lazy_nr is now
    lazy_max_pages() + 1.

 5. This is still over the threshold, so it tries to purge areas again,
    but doesn't find anything.

 6. Repeat 5.

If the system is running with only one CPU (which is typicial for kdump)
and preemption is disabled, then this will never make forward progress:
there aren't any more pages to purge, so it hangs.  If there is more
than one CPU or preemption is enabled, then the worker thread will spin
forever in the background.  (Note that if there were already pages to be
purged at the time that set_iounmap_nonlazy() was called, this bug is
avoided.)

This can be reproduced with anything that reads from /proc/vmcore
multiple times.  E.g., vmcore-dmesg /proc/vmcore.

It turns out that improvements to vmap() over the years have obsoleted
the need for this "optimization".  I benchmarked `dd if=/proc/vmcore
of=/dev/null` with 4k and 1M read sizes on a system with a 32GB vmcore.
The test was run on 5.17, 5.18-rc1 with a fix that avoided the hang, and
5.18-rc1 with set_iounmap_nonlazy() removed entirely:

    |5.17  |5.18+fix|5.18+removal
  4k|40.86s|  40.09s|      26.73s
  1M|24.47s|  23.98s|      21.84s

The removal was the fastest (by a wide margin with 4k reads).  This
patch removes set_iounmap_nonlazy().

Link: https://lkml.kernel.org/r/52f819991051f9b865e9ce25605509bfdbacadcd.1649277321.git.osandov@fb.com
Fixes: 690467c8  ("mm/vmalloc: Move draining areas out of caller context")
Signed-off-by: Omar Sandoval <osandov@fb.com>
Acked-by: Chris Down <chris@chrisdown.name>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Despite Mike's attempted fix (925346c1), regressions reports
continue:

  https://lore.kernel.org/lkml/cb5b81bd-9882-e5dc-cd22-54bdbaaefbbc@leemhuis.info/
  https://bugzilla.kernel.org/show_bug.cgi?id=215720
  https://lkml.kernel.org/r/b685f3d0-da34-531d-1aa9-479accd3e21b@leemhuis.info

So revert this patch.

Fixes: 9630f0d6 ("fs/binfmt_elf: use PT_LOAD p_align values for static PIE")
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Fangrui Song <maskray@google.com>
Cc: H.J. Lu <hjl.tools@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Sandeep Patil <sspatil@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 925346c1 ("fs/binfmt_elf: fix PT_LOAD p_align values for
loaders") was an attempt to fix regressions due to 9630f0d6
("fs/binfmt_elf: use PT_LOAD p_align values for static PIE").

But regressionss continue to be reported:

  https://lore.kernel.org/lkml/cb5b81bd-9882-e5dc-cd22-54bdbaaefbbc@leemhuis.info/
  https://bugzilla.kernel.org/show_bug.cgi?id=215720
  https://lkml.kernel.org/r/b685f3d0-da34-531d-1aa9-479accd3e21b@leemhuis.info

This patch reverts the fix, so the original can also be reverted.

Fixes: 925346c1 ("fs/binfmt_elf: fix PT_LOAD p_align values for loaders")
Cc: H.J. Lu <hjl.tools@gmail.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sandeep Patil <sspatil@google.com>
Cc: Fangrui Song <maskray@google.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

It is possible for poisoned hugetlb pages to reside on the free lists.
The huge page allocation routines which dequeue entries from the free
lists make a point of avoiding poisoned pages.  There is no such check
and avoidance in the demote code path.

If a hugetlb page on the is on a free list, poison will only be set in
the head page rather then the page with the actual error.  If such a
page is demoted, then the poison flag may follow the wrong page.  A page
without error could have poison set, and a page with poison could not
have the flag set.

Check for poison before attempting to demote a hugetlb page.  Also,
return -EBUSY to the caller if only poisoned pages are on the free list.

Link: https://lkml.kernel.org/r/20220307215707.50916-1-mike.kravetz@oracle.com
Fixes: 8531fc6f ("hugetlb: add hugetlb demote page support")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The below warning is reported when CONFIG_COMPACTION=n:

   mm/compaction.c:56:27: warning: 'HPAGE_FRAG_CHECK_INTERVAL_MSEC' defined but not used [-Wunused-const-variable=]
      56 | static const unsigned int HPAGE_FRAG_CHECK_INTERVAL_MSEC = 500;
         |                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix it by moving 'HPAGE_FRAG_CHECK_INTERVAL_MSEC' under
CONFIG_COMPACTION defconfig.

Also since this is just a 'static const int' type, use #define for it.

Link: https://lkml.kernel.org/r/1647608518-20924-1-git-send-email-quic_charante@quicinc.comSigned-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Nitin Gupta <nigupta@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Two processes under CLONE_VM cloning, user process can be corrupted by
seeing zeroed page unexpectedly.

      CPU A                        CPU B

  do_swap_page                do_swap_page
  SWP_SYNCHRONOUS_IO path     SWP_SYNCHRONOUS_IO path
  swap_readpage valid data
    swap_slot_free_notify
      delete zram entry
                              swap_readpage zeroed(invalid) data
                              pte_lock
                              map the *zero data* to userspace
                              pte_unlock
  pte_lock
  if (!pte_same)
    goto out_nomap;
  pte_unlock
  return and next refault will
  read zeroed data

The swap_slot_free_notify is bogus for CLONE_VM case since it doesn't
increase the refcount of swap slot at copy_mm so it couldn't catch up
whether it's safe or not to discard data from backing device.  In the
case, only the lock it could rely on to synchronize swap slot freeing is
page table lock.  Thus, this patch gets rid of the swap_slot_free_notify
function.  With this patch, CPU A will see correct data.

      CPU A                        CPU B

  do_swap_page                do_swap_page
  SWP_SYNCHRONOUS_IO path     SWP_SYNCHRONOUS_IO path
                              swap_readpage original data
                              pte_lock
                              map the original data
                              swap_free
                                swap_range_free
                                  bd_disk->fops->swap_slot_free_notify
  swap_readpage read zeroed data
                              pte_unlock
  pte_lock
  if (!pte_same)
    goto out_nomap;
  pte_unlock
  return
  on next refault will see mapped data by CPU B

The concern of the patch would increase memory consumption since it
could keep wasted memory with compressed form in zram as well as
uncompressed form in address space.  However, most of cases of zram uses
no readahead and do_swap_page is followed by swap_free so it will free
the compressed form from in zram quickly.

Link: https://lkml.kernel.org/r/YjTVVxIAsnKAXjTd@google.com
Fixes: 0bcac06f ("mm, swap: skip swapcache for swapin of synchronous device")
Reported-by: Ivan Babrou <ivan@cloudflare.com>
Tested-by: Ivan Babrou <ivan@cloudflare.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org>	[4.14+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Since commit 6aa303de ("mm, vmscan: only allocate and reclaim from
zones with pages managed by the buddy allocator") only zones with free
memory are included in a built zonelist.  This is problematic when e.g.
all memory of a zone has been ballooned out when zonelists are being
rebuilt.

The decision whether to rebuild the zonelists when onlining new memory
is done based on populated_zone() returning 0 for the zone the memory
will be added to.  The new zone is added to the zonelists only, if it
has free memory pages (managed_zone() returns a non-zero value) after
the memory has been onlined.  This implies, that onlining memory will
always free the added pages to the allocator immediately, but this is
not true in all cases: when e.g. running as a Xen guest the onlined new
memory will be added only to the ballooned memory list, it will be freed
only when the guest is being ballooned up afterwards.

Another problem with using managed_zone() for the decision whether a
zone is being added to the zonelists is, that a zone with all memory
used will in fact be removed from all zonelists in case the zonelists
happen to be rebuilt.

Use populated_zone() when building a zonelist as it has been done before
that commit.

There was a report that QubesOS (based on Xen) is hitting this problem.
Xen has switched to use the zone device functionality in kernel 5.9 and
QubesOS wants to use memory hotplugging for guests in order to be able
to start a guest with minimal memory and expand it as needed.  This was
the report leading to the patch.

Link: https://lkml.kernel.org/r/20220407120637.9035-1-jgross@suse.com
Fixes: 6aa303de ("mm, vmscan: only allocate and reclaim from zones with pages managed by the buddy allocator")
Signed-off-by: Juergen Gross <jgross@suse.com>
Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>