This patch moves the asid_generation from the vcpu to the vmcb
in order to track the ASID generation that was active the last
time the vmcb was run. If sd->asid_generation changes between
two runs, the old ASID is invalid and must be changed.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Cathy Avery <cavery@redhat.com>
Message-Id: <20210112164313.4204-3-cavery@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch moves the physical cpu tracking from the vcpu
to the vmcb in svm_switch_vmcb. If either vmcb01 or vmcb02
change physical cpus from one vmrun to the next the vmcb's
previous cpu is preserved for comparison with the current
cpu and the vmcb is marked dirty if different. This prevents
the processor from using old cached data for a vmcb that may
have been updated on a prior run on a different processor.

It also moves the physical cpu check from svm_vcpu_load
to pre_svm_run as the check only needs to be done at run.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Cathy Avery <cavery@redhat.com>
Message-Id: <20210112164313.4204-2-cavery@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

svm->vmcb will now point to a separate vmcb for L1 (not nested) or L2
(nested).

The main advantages are removing get_host_vmcb and hsave, in favor of
concepts that are shared with VMX.

We don't need anymore to stash the L1 registers in hsave while L2
runs, but we need to copy the VMLOAD/VMSAVE registers from VMCB01 to
VMCB02 and back.  This more or less has the same cost, but code-wise
nested_svm_vmloadsave can be reused.

This patch omits several optimizations that are possible:

- for simplicity there is some wholesale copying of vmcb.control areas
which can go away.

- we should be able to better use the VMCB01 and VMCB02 clean bits.

- another possibility is to always use VMCB01 for VMLOAD and VMSAVE,
thus avoiding the copy of VMLOAD/VMSAVE registers from VMCB01 to
VMCB02 and back.

Tested:
kvm-unit-tests
kvm self tests
Loaded fedora nested guest on fedora
Signed-off-by: Cathy Avery <cavery@redhat.com>
Message-Id: <20201011184818.3609-3-cavery@redhat.com>
[Fix conflicts; keep VMCB02 G_PAT up to date whenever guest writes the
 PAT MSR; do not copy CR4 over from VMCB01 as it is not needed anymore; add
 a few more comments. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Override the shadow root level in the MMU context when configuring
NPT for shadowing nested NPT.  The level is always tied to the TDP level
of the host, not whatever level the guest happens to be using.

Fixes: 096586fd ("KVM: nSVM: Correctly set the shadow NPT root level in its MMU role")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Don't strip the C-bit from the faulting address on an intercepted #PF,
the address is a virtual address, not a physical address.

Fixes: 0ede79e1 ("KVM: SVM: Clear C-bit from the page fault address")
Cc: stable@vger.kernel.org
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-13-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

WARN if KVM is about to dereference a NULL pae_root or lm_root when
loading an MMU, and convert the BUG() on a bad shadow_root_level into a
WARN (now that errors are handled cleanly).  With nested NPT, botching
the level and sending KVM down the wrong path is all too easy, and the
on-demand allocation of pae_root and lm_root means bugs crash the host.
Obviously, KVM could unconditionally allocate the roots, but that's
arguably a worse failure mode as it would potentially corrupt the guest
instead of crashing it.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-18-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

For clarity, explicitly skip syncing roots if the MMU load failed
instead of relying on the !VALID_PAGE check in kvm_mmu_sync_roots().
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Unexport the MMU load and unload helpers now that they are no longer
used (incorrectly) in vendor code.

Opportunistically move the kvm_mmu_sync_roots() declaration into mmu.h,
it should not be exposed to vendor code.

No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-16-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Defer unloading the MMU after a INVPCID until the instruction emulation
has completed, i.e. until after RIP has been updated.

On VMX, this is a benign bug as VMX doesn't touch the MMU when skipping
an emulated instruction.  However, on SVM, if nrip is disabled, the
emulator is used to skip an instruction, which would lead to fireworks
if the emulator were invoked without a valid MMU.

Fixes: eb4b248e ("kvm: vmx: Support INVPCID in shadow paging mode")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-15-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Defer reloading the MMU after a EPTP successful EPTP switch.  The VMFUNC
instruction itself is executed in the previous EPTP context, any side
effects, e.g. updating RIP, should occur in the old context.  Practically
speaking, this bug is benign as VMX doesn't touch the MMU when skipping
an emulated instruction, nor does queuing a single-step #DB.  No other
post-switch side effects exist.

Fixes: 41ab9372 ("KVM: nVMX: Emulate EPTP switching for the L1 hypervisor")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Set the C-bit in SPTEs that are set outside of the normal MMU flows,
specifically the PDPDTRs and the handful of special cased "LM root"
entries, all of which are shadow paging only.

Note, the direct-mapped-root PDPTR handling is needed for the scenario
where paging is disabled in the guest, in which case KVM uses a direct
mapped MMU even though TDP is disabled.

Fixes: d0ec49d4 ("kvm/x86/svm: Support Secure Memory Encryption within KVM")
Cc: stable@vger.kernel.org
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-11-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Exempt NULL PAE roots from the check to detect leaks, since
kvm_mmu_free_roots() doesn't set them back to INVALID_PAGE.  Stop hiding
the WARNs to detect PAE root leaks behind MMU_WARN_ON, the hidden WARNs
obviously didn't do their job given the hilarious number of bugs that
could lead to PAE roots being leaked, not to mention the above false
positive.

Opportunistically delete a warning on root_hpa being valid, there's
nothing special about 4/5-level shadow pages that warrants a WARN.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Check the validity of the PDPTRs before allocating any of the PAE roots,
otherwise a bad PDPTR will cause KVM to leak any previously allocated
roots.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Hold the mmu_lock for write for the entire duration of allocating and
initializing an MMU's roots.  This ensures there are MMU pages available
and thus prevents root allocations from failing.  That in turn fixes a
bug where KVM would fail to free valid PAE roots if a one of the later
roots failed to allocate.

Add a comment to make_mmu_pages_available() to call out that the limit
is a soft limit, e.g. KVM will temporarily exceed the threshold if a
page fault allocates multiple shadow pages and there was only one page
"available".

Note, KVM _still_ leaks the PAE roots if the guest PDPTR checks fail.
This will be addressed in a future commit.

Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Move the on-demand allocation of the pae_root and lm_root pages, used by
nested NPT for 32-bit L1s, into a separate helper.  This will allow a
future patch to hold mmu_lock while allocating the non-special roots so
that make_mmu_pages_available() can be checked once at the start of root
allocation, and thus avoid having to deal with failure in the middle of
root allocation.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Allocate lm_root before the PAE roots so that the PAE roots aren't
leaked if the memory allocation for the lm_root happens to fail.

Note, KVM can still leak PAE roots if mmu_check_root() fails on a guest's
PDPTR, or if mmu_alloc_root() fails due to MMU pages not being available.
Those issues will be fixed in future commits.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Grab 'mmu' and do s/vcpu->arch.mmu/mmu to shorten line lengths and yield
smaller diffs when moving code around in future cleanup without forcing
the new code to use the same ugly pattern.

No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Allocate the so called pae_root page on-demand, along with the lm_root
page, when shadowing 32-bit NPT with 64-bit NPT, i.e. when running a
32-bit L1.  KVM currently only allocates the page when NPT is disabled,
or when L0 is 32-bit (using PAE paging).

Note, there is an existing memory leak involving the MMU roots, as KVM
fails to free the PAE roots on failure.  This will be addressed in a
future commit.

Fixes: ee6268ba ("KVM: x86: Skip pae_root shadow allocation if tdp enabled")
Fixes: b6b80c78 ("KVM: x86/mmu: Allocate PAE root array when using SVM's 32-bit NPT")
Cc: stable@vger.kernel.org
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The new per-cpu stat 'nested_run' is introduced in order to track if L1 VM
is running or used to run L2 VM.

An example of the usage of 'nested_run' is to help the host administrator
to easily track if any L1 VM is used to run L2 VM. Suppose there is issue
that may happen with nested virtualization, the administrator will be able
to easily narrow down and confirm if the issue is due to nested
virtualization via 'nested_run'. For example, whether the fix like
commit 88dddc11 ("KVM: nVMX: do not use dangling shadow VMCS after
guest reset") is required.

Cc: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Message-Id: <20210305225747.7682-1-dongli.zhang@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Doing a

	prctl(PR_SET_MM, PR_SET_MM_AUXV, addr, 1);

will copy 1 byte from userspace to (quite big) on-stack array
and then stash everything to mm->saved_auxv.
AT_NULL terminator will be inserted at the very end.

/proc/*/auxv handler will find that AT_NULL terminator
and copy original stack contents to userspace.

This devious scheme requires CAP_SYS_RESOURCE.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull irq fixes from Thomas Gleixner:
 "A set of irqchip updates:

   - Make the GENERIC_IRQ_MULTI_HANDLER configuration correct

   - Add a missing DT compatible string for the Ingenic driver

   - Remove the pointless debugfs_file pointer from struct irqdomain"

* tag 'irq-urgent-2021-03-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/ingenic: Add support for the JZ4760
  dt-bindings/irq: Add compatible string for the JZ4760B
  irqchip: Do not blindly select CONFIG_GENERIC_IRQ_MULTI_HANDLER
  ARM: ep93xx: Select GENERIC_IRQ_MULTI_HANDLER directly
  irqdomain: Remove debugfs_file from struct irq_domain

Pull timer fix from Thomas Gleixner:
 "A single fix in for hrtimers to prevent an interrupt storm caused by
  the lack of reevaluation of the timers which expire in softirq context
  under certain circumstances, e.g. when the clock was set"

* tag 'timers-urgent-2021-03-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  hrtimer: Update softirq_expires_next correctly after __hrtimer_get_next_event()

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

   - Prevent a NULL pointer dereference in the migration_stop_cpu()
     mechanims

   - Prevent self concurrency of affine_move_task()

   - Small fixes and cleanups related to task migration/affinity setting

   - Ensure that sync_runqueues_membarrier_state() is invoked on the
     current CPU when it is in the cpu mask"

* tag 'sched-urgent-2021-03-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/membarrier: fix missing local execution of ipi_sync_rq_state()
  sched: Simplify set_affinity_pending refcounts
  sched: Fix affine_move_task() self-concurrency
  sched: Optimize migration_cpu_stop()
  sched: Collate affine_move_task() stoppers
  sched: Simplify migration_cpu_stop()
  sched: Fix migration_cpu_stop() requeueing

Pull objtool fix from Thomas Gleixner:
 "A single objtool fix to handle the PUSHF/POPF validation correctly for
  the paravirt changes which modified arch_local_irq_restore not to use
  popf"

* tag 'objtool-urgent-2021-03-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool,x86: Fix uaccess PUSHF/POPF validation

Pull locking fixes from Thomas Gleixner:
 "A couple of locking fixes:

   - A fix for the static_call mechanism so it handles unaligned
     addresses correctly.

   - Make u64_stats_init() a macro so every instance gets a seperate
     lockdep key.

   - Make seqcount_latch_init() a macro as well to preserve the static
     variable which is used for the lockdep key"

* tag 'locking-urgent-2021-03-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  seqlock,lockdep: Fix seqcount_latch_init()
  u64_stats,lockdep: Fix u64_stats_init() vs lockdep
  static_call: Fix the module key fixup

Pull perf fixes from Borislav Petkov:

 - Make sure PMU internal buffers are flushed for per-CPU events too and
   properly handle PID/TID for large PEBS.

 - Handle the case properly when there's no PMU and therefore return an
   empty list of perf MSRs for VMX to switch instead of reading random
   garbage from the stack.

* tag 'perf_urgent_for_v5.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/perf: Use RET0 as default for guest_get_msrs to handle "no PMU" case
  perf/x86/intel: Set PERF_ATTACH_SCHED_CB for large PEBS and LBR
  perf/core: Flush PMU internal buffers for per-CPU events

Pull EFI fix from Ard Biesheuvel via Borislav Petkov:
 "Fix an oversight in the handling of EFI_RT_PROPERTIES_TABLE, which was
  added v5.10, but failed to take the SetVirtualAddressMap() RT service
  into account"

* tag 'efi-urgent-for-v5.12-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi: stub: omit SetVirtualAddressMap() if marked unsupported in RT_PROP table

Pull x86 fixes from Borislav Petkov:

 - A couple of SEV-ES fixes and robustifications: verify usermode stack
   pointer in NMI is not coming from the syscall gap, correctly track
   IRQ states in the #VC handler and access user insn bytes atomically
   in same handler as latter cannot sleep.

 - Balance 32-bit fast syscall exit path to do the proper work on exit
   and thus not confuse audit and ptrace frameworks.

 - Two fixes for the ORC unwinder going "off the rails" into KASAN
   redzones and when ORC data is missing.

* tag 'x86_urgent_for_v5.12_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/sev-es: Use __copy_from_user_inatomic()
  x86/sev-es: Correctly track IRQ states in runtime #VC handler
  x86/sev-es: Check regs->sp is trusted before adjusting #VC IST stack
  x86/sev-es: Introduce ip_within_syscall_gap() helper
  x86/entry: Fix entry/exit mismatch on failed fast 32-bit syscalls
  x86/unwind/orc: Silence warnings caused by missing ORC data
  x86/unwind/orc: Disable KASAN checking in the ORC unwinder, part 2

Pull powerpc fixes from Michael Ellerman:
 "Some more powerpc fixes for 5.12:

   - Fix wrong instruction encoding for lis in ppc_function_entry(),
     which could potentially lead to missed kprobes.

   - Fix SET_FULL_REGS on 32-bit and 64e, which prevented ptrace of
     non-volatile GPRs immediately after exec.

   - Clean up a missed SRR specifier in the recent interrupt rework.

   - Don't treat unrecoverable_exception() as an interrupt handler, it's
     called from other handlers so shouldn't do the interrupt entry/exit
     accounting itself.

   - Fix build errors caused by missing declarations for
     [en/dis]able_kernel_vsx().

  Thanks to Christophe Leroy, Daniel Axtens, Geert Uytterhoeven, Jiri
  Olsa, Naveen N. Rao, and Nicholas Piggin"

* tag 'powerpc-5.12-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/traps: unrecoverable_exception() is not an interrupt handler
  powerpc: Fix missing declaration of [en/dis]able_kernel_vsx()
  powerpc/64s/exception: Clean up a missed SRR specifier
  powerpc: Fix inverted SET_FULL_REGS bitop
  powerpc/64s: Use symbolic macros for function entry encoding
  powerpc/64s: Fix instruction encoding for lis in ppc_function_entry()

Pull KVM fixes from Paolo Bonzini:
 "More fixes for ARM and x86"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: LAPIC: Advancing the timer expiration on guest initiated write
  KVM: x86/mmu: Skip !MMU-present SPTEs when removing SP in exclusive mode
  KVM: kvmclock: Fix vCPUs > 64 can't be online/hotpluged
  kvm: x86: annotate RCU pointers
  KVM: arm64: Fix exclusive limit for IPA size
  KVM: arm64: Reject VM creation when the default IPA size is unsupported
  KVM: arm64: Ensure I-cache isolation between vcpus of a same VM
  KVM: arm64: Don't use cbz/adr with external symbols
  KVM: arm64: Fix range alignment when walking page tables
  KVM: arm64: Workaround firmware wrongly advertising GICv2-on-v3 compatibility
  KVM: arm64: Rename __vgic_v3_get_ich_vtr_el2() to __vgic_v3_get_gic_config()
  KVM: arm64: Don't access PMSELR_EL0/PMUSERENR_EL0 when no PMU is available
  KVM: arm64: Turn kvm_arm_support_pmu_v3() into a static key
  KVM: arm64: Fix nVHE hyp panic host context restore
  KVM: arm64: Avoid corrupting vCPU context register in guest exit
  KVM: arm64: nvhe: Save the SPE context early
  kvm: x86: use NULL instead of using plain integer as pointer
  KVM: SVM: Connect 'npt' module param to KVM's internal 'npt_enabled'
  KVM: x86: Ensure deadline timer has truly expired before posting its IRQ

Merge misc fixes from Andrew Morton:
 "28 patches.

  Subsystems affected by this series: mm (memblock, pagealloc, hugetlb,
  highmem, kfence, oom-kill, madvise, kasan, userfaultfd, memcg, and
  zram), core-kernel, kconfig, fork, binfmt, MAINTAINERS, kbuild, and
  ia64"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (28 commits)
  zram: fix broken page writeback
  zram: fix return value on writeback_store
  mm/memcg: set memcg when splitting page
  mm/memcg: rename mem_cgroup_split_huge_fixup to split_page_memcg and add nr_pages argument
  ia64: fix ptrace(PTRACE_SYSCALL_INFO_EXIT) sign
  ia64: fix ia64_syscall_get_set_arguments() for break-based syscalls
  mm/userfaultfd: fix memory corruption due to writeprotect
  kasan: fix KASAN_STACK dependency for HW_TAGS
  kasan, mm: fix crash with HW_TAGS and DEBUG_PAGEALLOC
  mm/madvise: replace ptrace attach requirement for process_madvise
  include/linux/sched/mm.h: use rcu_dereference in in_vfork()
  kfence: fix reports if constant function prefixes exist
  kfence, slab: fix cache_alloc_debugcheck_after() for bulk allocations
  kfence: fix printk format for ptrdiff_t
  linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP*
  MAINTAINERS: exclude uapi directories in API/ABI section
  binfmt_misc: fix possible deadlock in bm_register_write
  mm/highmem.c: fix zero_user_segments() with start > end
  hugetlb: do early cow when page pinned on src mm
  mm: use is_cow_mapping() across tree where proper
  ...

Merge tag 'irqchip-fixes-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/urgent

Pull irqchip fixes from Marc Zyngier:

  - More compatible strings for the Ingenic irqchip (introducing the
    JZ4760B SoC)
  - Select GENERIC_IRQ_MULTI_HANDLER on the ARM ep93xx platform
  - Drop all GENERIC_IRQ_MULTI_HANDLER selections from the irqchip
    Kconfig, now relying on the architecture to get it right
  - Drop the debugfs_file field from struct irq_domain, now that
    debugfs can track things on its own

Pull char/misc driver fixes from Greg KH:
 "Here are some small misc/char driver fixes to resolve some reported
  problems:

   - habanalabs driver fixes

   - Acrn build fixes (reported many times)

   - pvpanic module table export fix

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'char-misc-5.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  misc/pvpanic: Export module FDT device table
  misc: fastrpc: restrict user apps from sending kernel RPC messages
  virt: acrn: Correct type casting of argument of copy_from_user()
  virt: acrn: Use EPOLLIN instead of POLLIN
  virt: acrn: Use vfs_poll() instead of f_op->poll()
  virt: acrn: Make remove_cpu sysfs invisible with !CONFIG_HOTPLUG_CPU
  cpu/hotplug: Fix build error of using {add,remove}_cpu() with !CONFIG_SMP
  habanalabs: fix debugfs address translation
  habanalabs: Disable file operations after device is removed
  habanalabs: Call put_pid() when releasing control device
  drivers: habanalabs: remove unused dentry pointer for debugfs files
  habanalabs: mark hl_eq_inc_ptr() as static

Pull staging driver fixes from Greg KH:
 "Here are some small staging driver fixes for reported problems. They
  include:

   - wfx header file cleanup patch reverted as it could cause problems

   - comedi driver endian fixes

   - buffer overflow problems for staging wifi drivers

   - build dependency issue for rtl8192e driver

  All have been in linux-next for a while with no reported problems"

* tag 'staging-5.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: (23 commits)
  Revert "staging: wfx: remove unused included header files"
  staging: rtl8188eu: prevent ->ssid overflow in rtw_wx_set_scan()
  staging: rtl8188eu: fix potential memory corruption in rtw_check_beacon_data()
  staging: rtl8192u: fix ->ssid overflow in r8192_wx_set_scan()
  staging: comedi: pcl726: Use 16-bit 0 for interrupt data
  staging: comedi: ni_65xx: Use 16-bit 0 for interrupt data
  staging: comedi: ni_6527: Use 16-bit 0 for interrupt data
  staging: comedi: comedi_parport: Use 16-bit 0 for interrupt data
  staging: comedi: amplc_pc236_common: Use 16-bit 0 for interrupt data
  staging: comedi: pcl818: Fix endian problem for AI command data
  staging: comedi: pcl711: Fix endian problem for AI command data
  staging: comedi: me4000: Fix endian problem for AI command data
  staging: comedi: dmm32at: Fix endian problem for AI command data
  staging: comedi: das800: Fix endian problem for AI command data
  staging: comedi: das6402: Fix endian problem for AI command data
  staging: comedi: adv_pci1710: Fix endian problem for AI command data
  staging: comedi: addi_apci_1500: Fix endian problem for command sample
  staging: comedi: addi_apci_1032: Fix endian problem for COS sample
  staging: ks7010: prevent buffer overflow in ks_wlan_set_scan()
  staging: rtl8712: Fix possible buffer overflow in r8712_sitesurvey_cmd
  ...

Pull tty/serial fixes from Greg KH:
 "Here are some small tty and serial driver fixes to resolve some
  reported problems:

   - led tty trigger fixes based on review and were acked by the led
     maintainer

   - revert a max310x serial driver patch as it was causing problems

   - revert a pty change as it was also causing problems

  All of these have been in linux-next for a while with no reported
  problems"

* tag 'tty-5.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  Revert "drivers:tty:pty: Fix a race causing data loss on close"
  Revert "serial: max310x: rework RX interrupt handling"
  leds: trigger/tty: Use led_set_brightness_sync() from workqueue
  leds: trigger: Fix error path to not unlock the unlocked mutex

Pull USB fixes from Greg KH:
 "Here are a small number of USB fixes for 5.12-rc3 to resolve a bunch
  of reported issues:

   - usbip fixups for issues found by syzbot

   - xhci driver fixes and quirk additions

   - gadget driver fixes

   - dwc3 QCOM driver fix

   - usb-serial new ids and fixes

   - usblp fix for a long-time issue

   - cdc-acm quirk addition

   - other tiny fixes for reported problems

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'usb-5.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (25 commits)
  xhci: Fix repeated xhci wake after suspend due to uncleared internal wake state
  usb: xhci: Fix ASMedia ASM1042A and ASM3242 DMA addressing
  xhci: Improve detection of device initiated wake signal.
  usb: xhci: do not perform Soft Retry for some xHCI hosts
  usbip: fix vudc usbip_sockfd_store races leading to gpf
  usbip: fix vhci_hcd attach_store() races leading to gpf
  usbip: fix stub_dev usbip_sockfd_store() races leading to gpf
  usbip: fix vudc to check for stream socket
  usbip: fix vhci_hcd to check for stream socket
  usbip: fix stub_dev to check for stream socket
  usb: dwc3: qcom: Add missing DWC3 OF node refcount decrement
  USB: usblp: fix a hang in poll() if disconnected
  USB: gadget: udc: s3c2410_udc: fix return value check in s3c2410_udc_probe()
  usb: renesas_usbhs: Clear PIPECFG for re-enabling pipe with other EPNUM
  usb: dwc3: qcom: Honor wakeup enabled/disabled state
  usb: gadget: f_uac1: stop playback on function disable
  usb: gadget: f_uac2: always increase endpoint max_packet_size by one audio slot
  USB: gadget: u_ether: Fix a configfs return code
  usb: dwc3: qcom: add ACPI device id for sc8180x
  Goodix Fingerprint device is not a modem
  ...

Pull erofs fix from Gao Xiang:
 "Fix an urgent regression introduced by commit baa2c7c9 ("block:
  set .bi_max_vecs as actual allocated vector number"), which could
  cause unexpected hung since linux 5.12-rc1.

  Resolve it by avoiding using bio->bi_max_vecs completely"

* tag 'erofs-for-5.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  erofs: fix bio->bi_max_vecs behavior change

Merge tag 'kbuild-fixes-v5.12-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - avoid 'make image_name' invoking syncconfig

 - fix a couple of bugs in scripts/dummy-tools

 - fix LLD_VENDOR and locale issues in scripts/ld-version.sh

 - rebuild GCC plugins when the compiler is upgraded

 - allow LTO to be enabled with KASAN_HW_TAGS

 - allow LTO to be enabled without LLVM=1

* tag 'kbuild-fixes-v5.12-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: fix ld-version.sh to not be affected by locale
  kbuild: remove meaningless parameter to $(call if_changed_rule,dtc)
  kbuild: remove LLVM=1 test from HAS_LTO_CLANG
  kbuild: remove unneeded -O option to dtc
  kbuild: dummy-tools: adjust to scripts/cc-version.sh
  kbuild: Allow LTO to be selected with KASAN_HW_TAGS
  kbuild: dummy-tools: support MPROFILE_KERNEL checks for ppc
  kbuild: rebuild GCC plugins when the compiler is upgraded
  kbuild: Fix ld-version.sh script if LLD was built with LLD_VENDOR
  kbuild: dummy-tools: fix inverted tests for gcc
  kbuild: add image_name to no-sync-config-targets

commit 0d835962 ("zram: support page writeback") introduced two
problems.  It overwrites writeback_store's return value as kstrtol's
return value, which makes return value zero so user could see zero as
return value of write syscall even though it wrote data successfully.

It also breaks index value in the loop in that it doesn't increase the
index any longer.  It means it can write only first starting block index
so user couldn't write all idle pages in the zram so lose memory saving
chance.

This patch fixes those issues.

Link: https://lkml.kernel.org/r/20210312173949.2197662-2-minchan@kernel.org
Fixes: 0d835962("zram: support page writeback")
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reported-by: Amos Bianchi <amosbianchi@google.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: John Dias <joaodias@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>