Pull powerpc fix from Michael Ellerman:

 - Fix KVM PR on 32-bit, which was broken by some MMU code refactoring.

Thanks to: Alexander Graf, and Matt Evans.

* tag 'powerpc-5.18-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  KVM: PPC: Book3S PR: Enable MSR_DR for switch_mmu_context()

Commit 863771a28e27 ("powerpc/32s: Convert switch_mmu_context() to C")
moved the switch_mmu_context() to C. While in principle a good idea, it
meant that the function now uses the stack. The stack is not accessible
from real mode though.

So to keep calling the function, let's turn on MSR_DR while we call it.
That way, all pointer references to the stack are handled virtually.

In addition, make sure to save/restore r12 on the stack, as it may get
clobbered by the C function.

Fixes: 863771a28e27 ("powerpc/32s: Convert switch_mmu_context() to C")
Cc: stable@vger.kernel.org # v5.14+
Reported-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220510123717.24508-1-graf@amazon.com

Pull powerpc fixes from Michael Ellerman:

 - Fix the DWARF CFI in our VDSO time functions, allowing gdb to
   backtrace through them correctly.

 - Fix a buffer overflow in the papr_scm driver, only triggerable by
   hypervisor input.

 - A fix in the recently added QoS handling for VAS (used for
   communicating with coprocessors).

Thanks to Alan Modra, Haren Myneni, Kajol Jain, and Segher Boessenkool.

* tag 'powerpc-5.18-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/papr_scm: Fix buffer overflow issue with CONFIG_FORTIFY_SOURCE
  powerpc/vdso: Fix incorrect CFI in gettimeofday.S
  powerpc/pseries/vas: Use QoS credits from the userspace

With CONFIG_FORTIFY_SOURCE enabled, string functions will also perform
dynamic checks for string size which can panic the kernel, like incase
of overflow detection.

In papr_scm, papr_scm_pmu_check_events function uses stat->stat_id with
string operations, to populate the nvdimm_events_map array. Since
stat_id variable is not NULL terminated, the kernel panics with
CONFIG_FORTIFY_SOURCE enabled at boot time.

Below are the logs of kernel panic:

  detected buffer overflow in __fortify_strlen
  ------------[ cut here ]------------
  kernel BUG at lib/string_helpers.c:980!
  Oops: Exception in kernel mode, sig: 5 [#1]
  NIP [c00000000077dad0] fortify_panic+0x28/0x38
  LR [c00000000077dacc] fortify_panic+0x24/0x38
  Call Trace:
  [c0000022d77836e0] [c00000000077dacc] fortify_panic+0x24/0x38 (unreliable)
  [c00800000deb2660] papr_scm_pmu_check_events.constprop.0+0x118/0x220 [papr_scm]
  [c00800000deb2cb0] papr_scm_probe+0x288/0x62c [papr_scm]
  [c0000000009b46a8] platform_probe+0x98/0x150

Fix this issue by using kmemdup_nul() to copy the content of
stat->stat_id directly to the nvdimm_events_map array.

mpe: stat->stat_id comes from the hypervisor, not userspace, so there is
no security exposure.

Fixes: 4c08d4bbc089 ("powerpc/papr_scm: Add perf interface support")
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220505153451.35503-1-kjain@linux.ibm.com

As reported by Alan, the CFI (Call Frame Information) in the VDSO time
routines is incorrect since commit ce7d8056e38b ("powerpc/vdso: Prepare
for switching VDSO to generic C implementation.").

DWARF has a concept called the CFA (Canonical Frame Address), which on
powerpc is calculated as an offset from the stack pointer (r1). That
means when the stack pointer is changed there must be a corresponding
CFI directive to update the calculation of the CFA.

The current code is missing those directives for the changes to r1,
which prevents gdb from being able to generate a backtrace from inside
VDSO functions, eg:

  Breakpoint 1, 0x00007ffff7f804dc in __kernel_clock_gettime ()
  (gdb) bt
  #0  0x00007ffff7f804dc in __kernel_clock_gettime ()
  #1  0x00007ffff7d8872c in clock_gettime@@GLIBC_2.17 () from /lib64/libc.so.6
  #2  0x00007fffffffd960 in ?? ()
  #3  0x00007ffff7d8872c in clock_gettime@@GLIBC_2.17 () from /lib64/libc.so.6
  Backtrace stopped: frame did not save the PC

Alan helpfully describes some rules for correctly maintaining the CFI information:

  1) Every adjustment to the current frame address reg (ie. r1) must be
     described, and exactly at the instruction where r1 changes. Why?
     Because stack unwinding might want to access previous frames.

  2) If a function changes LR or any non-volatile register, the save
     location for those regs must be given. The CFI can be at any
     instruction after the saves up to the point that the reg is
     changed.
     (Exception: LR save should be described before a bl. not after)

  3) If asychronous unwind info is needed then restores of LR and
     non-volatile regs must also be described. The CFI can be at any
     instruction after the reg is restored up to the point where the
     save location is (potentially) trashed.

Fix the inability to backtrace by adding CFI directives describing the
changes to r1, ie. satisfying rule 1.

Also change the information for LR to point to the copy saved on the
stack, not the value in r0 that will be overwritten by the function
call.

Finally, add CFI directives describing the save/restore of r2.

With the fix gdb can correctly back trace and navigate up and down the stack:

  Breakpoint 1, 0x00007ffff7f804dc in __kernel_clock_gettime ()
  (gdb) bt
  #0  0x00007ffff7f804dc in __kernel_clock_gettime ()
  #1  0x00007ffff7d8872c in clock_gettime@@GLIBC_2.17 () from /lib64/libc.so.6
  #2  0x0000000100015b60 in gettime ()
  #3  0x000000010000c8bc in print_long_format ()
  #4  0x000000010000d180 in print_current_files ()
  #5  0x00000001000054ac in main ()
  (gdb) up
  #1  0x00007ffff7d8872c in clock_gettime@@GLIBC_2.17 () from /lib64/libc.so.6
  (gdb)
  #2  0x0000000100015b60 in gettime ()
  (gdb)
  #3  0x000000010000c8bc in print_long_format ()
  (gdb)
  #4  0x000000010000d180 in print_current_files ()
  (gdb)
  #5  0x00000001000054ac in main ()
  (gdb)
  Initial frame selected; you cannot go up.
  (gdb) down
  #4  0x000000010000d180 in print_current_files ()
  (gdb)
  #3  0x000000010000c8bc in print_long_format ()
  (gdb)
  #2  0x0000000100015b60 in gettime ()
  (gdb)
  #1  0x00007ffff7d8872c in clock_gettime@@GLIBC_2.17 () from /lib64/libc.so.6
  (gdb)
  #0  0x00007ffff7f804dc in __kernel_clock_gettime ()
  (gdb)

Fixes: ce7d8056e38b ("powerpc/vdso: Prepare for switching VDSO to generic C implementation.")
Cc: stable@vger.kernel.org # v5.11+
Reported-by: Alan Modra <amodra@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Link: https://lore.kernel.org/r/20220502125010.1319370-1-mpe@ellerman.id.au

The user can change the QoS credits dynamically with the
management console interface which notifies OS with sysfs. After
returning from the OS interface successfully, the management
console updates the hypervisor. Since the VAS capabilities in
the hypervisor is not updated when the OS gets the update,
the kernel is using the old total credits value from the
hypervisor. Fix this issue by using the new QoS credits
from the userspace instead of depending on VAS capabilities
from the hypervisor.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/76d156f8af1e03cc09369d68e0bfad0c40031bcc.camel@linux.ibm.com

Pull powerpc fixes from Michael Ellerman:

 - Partly revert a change to our timer_interrupt() that caused lockups
   with high res timers disabled.

 - Fix a bug in KVM TCE handling that could corrupt kernel memory.

 - Two commits fixing Power9/Power10 perf alternative event selection.

Thanks to Alexey Kardashevskiy, Athira Rajeev, David Gibson, Frederic
Barrat, Madhavan Srinivasan, Miguel Ojeda, and Nicholas Piggin.

* tag 'powerpc-5.18-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/perf: Fix 32bit compile
  powerpc/perf: Fix power10 event alternatives
  powerpc/perf: Fix power9 event alternatives
  KVM: PPC: Fix TCE handling for VFIO
  powerpc/time: Always set decrementer in timer_interrupt()

Pull kvm fixes from Paolo Bonzini:
 "The main and larger change here is a workaround for AMD's lack of
  cache coherency for encrypted-memory guests.

  I have another patch pending, but it's waiting for review from the
  architecture maintainers.

  RISC-V:

   - Remove 's' & 'u' as valid ISA extension

   - Do not allow disabling the base extensions 'i'/'m'/'a'/'c'

  x86:

   - Fix NMI watchdog in guests on AMD

   - Fix for SEV cache incoherency issues

   - Don't re-acquire SRCU lock in complete_emulated_io()

   - Avoid NULL pointer deref if VM creation fails

   - Fix race conditions between APICv disabling and vCPU creation

   - Bugfixes for disabling of APICv

   - Preserve BSP MSR_KVM_POLL_CONTROL across suspend/resume

  selftests:

   - Do not use bitfields larger than 32-bits, they differ between GCC
     and clang"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  kvm: selftests: introduce and use more page size-related constants
  kvm: selftests: do not use bitfields larger than 32-bits for PTEs
  KVM: SEV: add cache flush to solve SEV cache incoherency issues
  KVM: SVM: Flush when freeing encrypted pages even on SME_COHERENT CPUs
  KVM: SVM: Simplify and harden helper to flush SEV guest page(s)
  KVM: selftests: Silence compiler warning in the kvm_page_table_test
  KVM: x86/pmu: Update AMD PMC sample period to fix guest NMI-watchdog
  x86/kvm: Preserve BSP MSR_KVM_POLL_CONTROL across suspend/resume
  KVM: SPDX style and spelling fixes
  KVM: x86: Skip KVM_GUESTDBG_BLOCKIRQ APICv update if APICv is disabled
  KVM: x86: Pend KVM_REQ_APICV_UPDATE during vCPU creation to fix a race
  KVM: nVMX: Defer APICv updates while L2 is active until L1 is active
  KVM: x86: Tag APICv DISABLE inhibit, not ABSENT, if APICv is disabled
  KVM: Initialize debugfs_dentry when a VM is created to avoid NULL deref
  KVM: Add helpers to wrap vcpu->srcu_idx and yell if it's abused
  KVM: RISC-V: Use kvm_vcpu.srcu_idx, drop RISC-V's unnecessary copy
  KVM: x86: Don't re-acquire SRCU lock in complete_emulated_io()
  RISC-V: KVM: Restrict the extensions that can be disabled
  RISC-V: KVM: Remove 's' & 'u' as valid ISA extension

Add wrappers to acquire/release KVM's SRCU lock when stashing the index
in vcpu->src_idx, along with rudimentary detection of illegal usage,
e.g. re-acquiring SRCU and thus overwriting vcpu->src_idx.  Because the
SRCU index is (currently) either 0 or 1, illegal nesting bugs can go
unnoticed for quite some time and only cause problems when the nested
lock happens to get a different index.

Wrap the WARNs in PROVE_RCU=y, and make them ONCE, otherwise KVM will
likely yell so loudly that it will bring the kernel to its knees.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Fabiano Rosas <farosas@linux.ibm.com>
Message-Id: <20220415004343.2203171-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The "read_bhrb" global symbol is only called under CONFIG_PPC64 of
arch/powerpc/perf/core-book3s.c but it is compiled for both 32 and 64 bit
anyway (and LLVM fails to link this on 32bit).

This fixes it by moving bhrb.o to obj64 targets.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220421025756.571995-1-aik@ozlabs.ru