linux.git/arch/powerpc/kernel, branch v5.15 Linux kernel source tree Merge tag 'powerpc-5.15-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux 2021-10-22T01:30:09+00:00 Linus Torvalds torvalds@linux-foundation.org 2021-10-22T01:30:09+00:00 0a3221b65874b5089f1742de59ef89f032b9f2ea Pull powerpc fixes from Michael Ellerman: - Fix a bug exposed by a previous fix, where running guests with certain SMT topologies could crash the host on Power8. - Fix atomic sleep warnings when re-onlining CPUs, when PREEMPT is enabled. Thanks to Nathan Lynch, Srikar Dronamraju, and Valentin Schneider. * tag 'powerpc-5.15-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: powerpc/smp: do not decrement idle task preempt count in CPU offline powerpc/idle: Don't corrupt back chain when going idle 
Pull powerpc fixes from Michael Ellerman:

 - Fix a bug exposed by a previous fix, where running guests with
   certain SMT topologies could crash the host on Power8.

 - Fix atomic sleep warnings when re-onlining CPUs, when PREEMPT is
   enabled.

Thanks to Nathan Lynch, Srikar Dronamraju, and Valentin Schneider.

* tag 'powerpc-5.15-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/smp: do not decrement idle task preempt count in CPU offline
  powerpc/idle: Don't corrupt back chain when going idle
powerpc/smp: do not decrement idle task preempt count in CPU offline 2021-10-20T10:38:01+00:00 Nathan Lynch nathanl@linux.ibm.com 2021-10-15T17:39:02+00:00 787252a10d9422f3058df9a4821f389e5326c440 With PREEMPT_COUNT=y, when a CPU is offlined and then onlined again, we get: BUG: scheduling while atomic: swapper/1/0/0x00000000 no locks held by swapper/1/0. CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.15.0-rc2+ #100 Call Trace: dump_stack_lvl+0xac/0x108 __schedule_bug+0xac/0xe0 __schedule+0xcf8/0x10d0 schedule_idle+0x3c/0x70 do_idle+0x2d8/0x4a0 cpu_startup_entry+0x38/0x40 start_secondary+0x2ec/0x3a0 start_secondary_prolog+0x10/0x14 This is because powerpc's arch_cpu_idle_dead() decrements the idle task's preempt count, for reasons explained in commit a7c2bb8279d2 ("powerpc: Re-enable preemption before cpu_die()"), specifically "start_secondary() expects a preempt_count() of 0." However, since commit 2c669ef6979c ("powerpc/preempt: Don't touch the idle task's preempt_count during hotplug") and commit f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled"), that justification no longer holds. The idle task isn't supposed to re-enable preemption, so remove the vestigial preempt_enable() from the CPU offline path. Tested with pseries and powernv in qemu, and pseries on PowerVM. Fixes: 2c669ef6979c ("powerpc/preempt: Don't touch the idle task's preempt_count during hotplug") Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211015173902.2278118-1-nathanl@linux.ibm.com 
With PREEMPT_COUNT=y, when a CPU is offlined and then onlined again, we
get:

BUG: scheduling while atomic: swapper/1/0/0x00000000
no locks held by swapper/1/0.
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.15.0-rc2+ #100
Call Trace:
 dump_stack_lvl+0xac/0x108
 __schedule_bug+0xac/0xe0
 __schedule+0xcf8/0x10d0
 schedule_idle+0x3c/0x70
 do_idle+0x2d8/0x4a0
 cpu_startup_entry+0x38/0x40
 start_secondary+0x2ec/0x3a0
 start_secondary_prolog+0x10/0x14

This is because powerpc's arch_cpu_idle_dead() decrements the idle task's
preempt count, for reasons explained in commit a7c2bb8279d2 ("powerpc:
Re-enable preemption before cpu_die()"), specifically "start_secondary()
expects a preempt_count() of 0."

However, since commit 2c669ef6979c ("powerpc/preempt: Don't touch the idle
task's preempt_count during hotplug") and commit f1a0a376ca0c ("sched/core:
Initialize the idle task with preemption disabled"), that justification no
longer holds.

The idle task isn't supposed to re-enable preemption, so remove the
vestigial preempt_enable() from the CPU offline path.

Tested with pseries and powernv in qemu, and pseries on PowerVM.

Fixes: 2c669ef6979c ("powerpc/preempt: Don't touch the idle task's preempt_count during hotplug")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211015173902.2278118-1-nathanl@linux.ibm.com
powerpc/idle: Don't corrupt back chain when going idle 2021-10-20T10:37:58+00:00 Michael Ellerman mpe@ellerman.id.au 2021-10-20T09:48:26+00:00 496c5fe25c377ddb7815c4ce8ecfb676f051e9b6 In isa206_idle_insn_mayloss() we store various registers into the stack red zone, which is allowed. However inside the IDLE_STATE_ENTER_SEQ_NORET macro we save r2 again, to 0(r1), which corrupts the stack back chain. We used to do the same in isa206_idle_insn_mayloss() itself, but we fixed that in 73287caa9210 ("powerpc64/idle: Fix SP offsets when saving GPRs"), however we missed that the macro also corrupts the back chain. Corrupting the back chain is bad for debuggability but doesn't necessarily cause a bug. However we recently changed the stack handling in some KVM code, and it now relies on the stack back chain being valid when it returns. The corruption causes that code to return with r1 pointing somewhere in kernel data, at some point LR is restored from the stack and we branch to NULL or somewhere else invalid. Only affects Power8 hosts running KVM guests, with dynamic_mt_modes enabled (which it is by default). The fixes tag below points to the commit that changed the KVM stack handling, exposing this bug. The actual corruption of the back chain has always existed since 948cf67c4726 ("powerpc: Add NAP mode support on Power7 in HV mode"). Fixes: 9b4416c5095c ("KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest()") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211020094826.3222052-1-mpe@ellerman.id.au 
In isa206_idle_insn_mayloss() we store various registers into the stack
red zone, which is allowed.

However inside the IDLE_STATE_ENTER_SEQ_NORET macro we save r2 again,
to 0(r1), which corrupts the stack back chain.

We used to do the same in isa206_idle_insn_mayloss() itself, but we
fixed that in 73287caa9210 ("powerpc64/idle: Fix SP offsets when saving
GPRs"), however we missed that the macro also corrupts the back chain.

Corrupting the back chain is bad for debuggability but doesn't
necessarily cause a bug.

However we recently changed the stack handling in some KVM code, and it
now relies on the stack back chain being valid when it returns. The
corruption causes that code to return with r1 pointing somewhere in
kernel data, at some point LR is restored from the stack and we branch
to NULL or somewhere else invalid.

Only affects Power8 hosts running KVM guests, with dynamic_mt_modes
enabled (which it is by default).

The fixes tag below points to the commit that changed the KVM stack
handling, exposing this bug. The actual corruption of the back chain has
always existed since 948cf67c4726 ("powerpc: Add NAP mode support on
Power7 in HV mode").

Fixes: 9b4416c5095c ("KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest()")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211020094826.3222052-1-mpe@ellerman.id.au
Merge tag 'powerpc-5.15-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux 2021-10-10T17:12:42+00:00 Linus Torvalds torvalds@linux-foundation.org 2021-10-10T17:12:42+00:00 efb52a7d9511df818391f1afa459507425833438 Pull powerpc fixes from Michael Ellerman: "A bit of a big batch, partly because I didn't send any last week, and also just because the BPF fixes happened to land this week. Summary: - Fix a regression hit by the IPR SCSI driver, introduced by the recent addition of MSI domains on pseries. - A big series including 8 BPF fixes, some with potential security impact and the rest various code generation issues. - Fix our program check assembler entry path, which was accidentally jumping into a gas macro and generating strange stack frames, which could confuse find_bug(). - A couple of fixes, and related changes, to fix corner cases in our machine check handling. - Fix our DMA IOMMU ops, which were not always returning the optimal DMA mask, leading to at least one device falling back to 32-bit DMA when it shouldn't. - A fix for KUAP handling on 32-bit Book3S. - Fix crashes seen when kdumping on some pseries systems. Thanks to Naveen N. Rao, Nicholas Piggin, Alexey Kardashevskiy, Cédric Le Goater, Christophe Leroy, Mahesh Salgaonkar, Abdul Haleem, Christoph Hellwig, Johan Almbladh, Stan Johnson" * tag 'powerpc-5.15-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: pseries/eeh: Fix the kdump kernel crash during eeh_pseries_init powerpc/32s: Fix kuap_kernel_restore() powerpc/pseries/msi: Add an empty irq_write_msi_msg() handler powerpc/64s: Fix unrecoverable MCE calling async handler from NMI powerpc/64/interrupt: Reconcile soft-mask state in NMI and fix false BUG powerpc/64: warn if local irqs are enabled in NMI or hardirq context powerpc/traps: do not enable irqs in _exception powerpc/64s: fix program check interrupt emergency stack path powerpc/bpf ppc32: Fix BPF_SUB when imm == 0x80000000 powerpc/bpf ppc32: Do not emit zero extend instruction for 64-bit BPF_END powerpc/bpf ppc32: Fix JMP32_JSET_K powerpc/bpf ppc32: Fix ALU32 BPF_ARSH operation powerpc/bpf: Emit stf barrier instruction sequences for BPF_NOSPEC powerpc/security: Add a helper to query stf_barrier type powerpc/bpf: Fix BPF_SUB when imm == 0x80000000 powerpc/bpf: Fix BPF_MOD when imm == 1 powerpc/bpf: Validate branch ranges powerpc/lib: Add helper to check if offset is within conditional branch range powerpc/iommu: Report the correct most efficient DMA mask for PCI devices 
Pull powerpc fixes from Michael Ellerman:
 "A bit of a big batch, partly because I didn't send any last week, and
  also just because the BPF fixes happened to land this week.

  Summary:

   - Fix a regression hit by the IPR SCSI driver, introduced by the
     recent addition of MSI domains on pseries.

   - A big series including 8 BPF fixes, some with potential security
     impact and the rest various code generation issues.

   - Fix our program check assembler entry path, which was accidentally
     jumping into a gas macro and generating strange stack frames, which
     could confuse find_bug().

   - A couple of fixes, and related changes, to fix corner cases in our
     machine check handling.

   - Fix our DMA IOMMU ops, which were not always returning the optimal
     DMA mask, leading to at least one device falling back to 32-bit DMA
     when it shouldn't.

   - A fix for KUAP handling on 32-bit Book3S.

   - Fix crashes seen when kdumping on some pseries systems.

  Thanks to Naveen N. Rao, Nicholas Piggin, Alexey Kardashevskiy, Cédric
  Le Goater, Christophe Leroy, Mahesh Salgaonkar, Abdul Haleem,
  Christoph Hellwig, Johan Almbladh, Stan Johnson"

* tag 'powerpc-5.15-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  pseries/eeh: Fix the kdump kernel crash during eeh_pseries_init
  powerpc/32s: Fix kuap_kernel_restore()
  powerpc/pseries/msi: Add an empty irq_write_msi_msg() handler
  powerpc/64s: Fix unrecoverable MCE calling async handler from NMI
  powerpc/64/interrupt: Reconcile soft-mask state in NMI and fix false BUG
  powerpc/64: warn if local irqs are enabled in NMI or hardirq context
  powerpc/traps: do not enable irqs in _exception
  powerpc/64s: fix program check interrupt emergency stack path
  powerpc/bpf ppc32: Fix BPF_SUB when imm == 0x80000000
  powerpc/bpf ppc32: Do not emit zero extend instruction for 64-bit BPF_END
  powerpc/bpf ppc32: Fix JMP32_JSET_K
  powerpc/bpf ppc32: Fix ALU32 BPF_ARSH operation
  powerpc/bpf: Emit stf barrier instruction sequences for BPF_NOSPEC
  powerpc/security: Add a helper to query stf_barrier type
  powerpc/bpf: Fix BPF_SUB when imm == 0x80000000
  powerpc/bpf: Fix BPF_MOD when imm == 1
  powerpc/bpf: Validate branch ranges
  powerpc/lib: Add helper to check if offset is within conditional branch range
  powerpc/iommu: Report the correct most efficient DMA mask for PCI devices
powerpc/64s: Fix unrecoverable MCE calling async handler from NMI 2021-10-07T08:54:55+00:00 Nicholas Piggin npiggin@gmail.com 2021-10-04T14:56:42+00:00 f08fb25bc66986b0952724530a640d9970fa52c1 The machine check handler is not considered NMI on 64s. The early handler is the true NMI handler, and then it schedules the machine_check_exception handler to run when interrupts are enabled. This works fine except the case of an unrecoverable MCE, where the true NMI is taken when MSR[RI] is clear, it can not recover, so it calls machine_check_exception directly so something might be done about it. Calling an async handler from NMI context can result in irq state and other things getting corrupted. This can also trigger the BUG at arch/powerpc/include/asm/interrupt.h:168 BUG_ON(!arch_irq_disabled_regs(regs) && !(regs->msr & MSR_EE)); Fix this by making an _async version of the handler which is called in the normal case, and a NMI version that is called for unrecoverable interrupts. Fixes: 2b43dd7653cc ("powerpc/64: enable MSR[EE] in irq replay pt_regs") Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Tested-by: Cédric Le Goater <clg@kaod.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211004145642.1331214-6-npiggin@gmail.com 
The machine check handler is not considered NMI on 64s. The early
handler is the true NMI handler, and then it schedules the
machine_check_exception handler to run when interrupts are enabled.

This works fine except the case of an unrecoverable MCE, where the true
NMI is taken when MSR[RI] is clear, it can not recover, so it calls
machine_check_exception directly so something might be done about it.

Calling an async handler from NMI context can result in irq state and
other things getting corrupted. This can also trigger the BUG at
  arch/powerpc/include/asm/interrupt.h:168
  BUG_ON(!arch_irq_disabled_regs(regs) && !(regs->msr & MSR_EE));

Fix this by making an _async version of the handler which is called
in the normal case, and a NMI version that is called for unrecoverable
interrupts.

Fixes: 2b43dd7653cc ("powerpc/64: enable MSR[EE] in irq replay pt_regs")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211004145642.1331214-6-npiggin@gmail.com
powerpc/64: warn if local irqs are enabled in NMI or hardirq context 2021-10-07T08:54:55+00:00 Nicholas Piggin npiggin@gmail.com 2021-10-04T14:56:40+00:00 ff058a8ada5df0d84e5537cfaf89d06d71501580 This can help catch bugs such as the one fixed by the previous change to prevent _exception() from enabling irqs. ppc32 could have a similar warning but it has no good config option to debug this stuff (the test may be overkill to add for production kernels). Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211004145642.1331214-4-npiggin@gmail.com 
This can help catch bugs such as the one fixed by the previous change
to prevent _exception() from enabling irqs.

ppc32 could have a similar warning but it has no good config option to
debug this stuff (the test may be overkill to add for production
kernels).

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211004145642.1331214-4-npiggin@gmail.com
powerpc/traps: do not enable irqs in _exception 2021-10-07T08:54:54+00:00 Nicholas Piggin npiggin@gmail.com 2021-10-04T14:56:39+00:00 d0afd44c05f8f4e4c91487c02d43c87a31552462 _exception can be called by machine check handlers when the MCE hits user code (e.g., pseries and powernv). This will enable local irqs because, which is a dicey thing to do in NMI or hard irq context. This seemed to worked out okay because a userspace MCE can basically be treated like a synchronous interrupt (after async / imprecise MCEs are filtered out). Since NMI and hard irq handlers have started growing nmi_enter / irq_enter, and more irq state sanity checks, this has started to cause problems (or at least trigger warnings). The Fixes tag to the commit which introduced this rather than try to work out exactly which commit was the first that could possibly cause a problem because that may be difficult to prove. Fixes: 9f2f79e3a3c1 ("powerpc: Disable interrupts in 64-bit kernel FP and vector faults") Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211004145642.1331214-3-npiggin@gmail.com 
_exception can be called by machine check handlers when the MCE hits
user code (e.g., pseries and powernv). This will enable local irqs
because, which is a dicey thing to do in NMI or hard irq context.

This seemed to worked out okay because a userspace MCE can basically be
treated like a synchronous interrupt (after async / imprecise MCEs are
filtered out). Since NMI and hard irq handlers have started growing
nmi_enter / irq_enter, and more irq state sanity checks, this has
started to cause problems (or at least trigger warnings).

The Fixes tag to the commit which introduced this rather than try to
work out exactly which commit was the first that could possibly cause a
problem because that may be difficult to prove.

Fixes: 9f2f79e3a3c1 ("powerpc: Disable interrupts in 64-bit kernel FP and vector faults")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211004145642.1331214-3-npiggin@gmail.com
powerpc/64s: fix program check interrupt emergency stack path 2021-10-07T08:54:54+00:00 Nicholas Piggin npiggin@gmail.com 2021-10-04T14:56:38+00:00 3e607dc4df180b72a38e75030cb0f94d12808712 Emergency stack path was jumping into a 3: label inside the __GEN_COMMON_BODY macro for the normal path after it had finished, rather than jumping over it. By a small miracle this is the correct place to build up a new interrupt frame with the existing stack pointer, so things basically worked okay with an added weird looking 700 trap frame on top (which had the wrong ->nip so it didn't decode bug messages either). Fix this by avoiding using numeric labels when jumping over non-trivial macros. Before: LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV Modules linked in: CPU: 0 PID: 88 Comm: sh Not tainted 5.15.0-rc2-00034-ge057cdade6e5 #2637 NIP: 7265677368657265 LR: c00000000006c0c8 CTR: c0000000000097f0 REGS: c0000000fffb3a50 TRAP: 0700 Not tainted MSR: 9000000000021031 <SF,HV,ME,IR,DR,LE> CR: 00000700 XER: 20040000 CFAR: c0000000000098b0 IRQMASK: 0 GPR00: c00000000006c964 c0000000fffb3cf0 c000000001513800 0000000000000000 GPR04: 0000000048ab0778 0000000042000000 0000000000000000 0000000000001299 GPR08: 000001e447c718ec 0000000022424282 0000000000002710 c00000000006bee8 GPR12: 9000000000009033 c0000000016b0000 00000000000000b0 0000000000000001 GPR16: 0000000000000000 0000000000000002 0000000000000000 0000000000000ff8 GPR20: 0000000000001fff 0000000000000007 0000000000000080 00007fff89d90158 GPR24: 0000000002000000 0000000002000000 0000000000000255 0000000000000300 GPR28: c000000001270000 0000000042000000 0000000048ab0778 c000000080647e80 NIP [7265677368657265] 0x7265677368657265 LR [c00000000006c0c8] ___do_page_fault+0x3f8/0xb10 Call Trace: [c0000000fffb3cf0] [c00000000000bdac] soft_nmi_common+0x13c/0x1d0 (unreliable) --- interrupt: 700 at decrementer_common_virt+0xb8/0x230 NIP: c0000000000098b8 LR: c00000000006c0c8 CTR: c0000000000097f0 REGS: c0000000fffb3d60 TRAP: 0700 Not tainted MSR: 9000000000021031 <SF,HV,ME,IR,DR,LE> CR: 22424282 XER: 20040000 CFAR: c0000000000098b0 IRQMASK: 0 GPR00: c00000000006c964 0000000000002400 c000000001513800 0000000000000000 GPR04: 0000000048ab0778 0000000042000000 0000000000000000 0000000000001299 GPR08: 000001e447c718ec 0000000022424282 0000000000002710 c00000000006bee8 GPR12: 9000000000009033 c0000000016b0000 00000000000000b0 0000000000000001 GPR16: 0000000000000000 0000000000000002 0000000000000000 0000000000000ff8 GPR20: 0000000000001fff 0000000000000007 0000000000000080 00007fff89d90158 GPR24: 0000000002000000 0000000002000000 0000000000000255 0000000000000300 GPR28: c000000001270000 0000000042000000 0000000048ab0778 c000000080647e80 NIP [c0000000000098b8] decrementer_common_virt+0xb8/0x230 LR [c00000000006c0c8] ___do_page_fault+0x3f8/0xb10 --- interrupt: 700 Instruction dump: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX ---[ end trace 6d28218e0cc3c949 ]--- After: ------------[ cut here ]------------ kernel BUG at arch/powerpc/kernel/exceptions-64s.S:491! Oops: Exception in kernel mode, sig: 5 [#1] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV Modules linked in: CPU: 0 PID: 88 Comm: login Not tainted 5.15.0-rc2-00034-ge057cdade6e5-dirty #2638 NIP: c0000000000098b8 LR: c00000000006bf04 CTR: c0000000000097f0 REGS: c0000000fffb3d60 TRAP: 0700 Not tainted MSR: 9000000000021031 <SF,HV,ME,IR,DR,LE> CR: 24482227 XER: 00040000 CFAR: c0000000000098b0 IRQMASK: 0 GPR00: c00000000006bf04 0000000000002400 c000000001513800 c000000001271868 GPR04: 00000000100f0d29 0000000042000000 0000000000000007 0000000000000009 GPR08: 00000000100f0d29 0000000024482227 0000000000002710 c000000000181b3c GPR12: 9000000000009033 c0000000016b0000 00000000100f0d29 c000000005b22f00 GPR16: 00000000ffff0000 0000000000000001 0000000000000009 00000000100eed90 GPR20: 00000000100eed90 0000000010000000 000000001000a49c 00000000100f1430 GPR24: c000000001271868 0000000002000000 0000000000000215 0000000000000300 GPR28: c000000001271800 0000000042000000 00000000100f0d29 c000000080647860 NIP [c0000000000098b8] decrementer_common_virt+0xb8/0x230 LR [c00000000006bf04] ___do_page_fault+0x234/0xb10 Call Trace: Instruction dump: 4182000c 39400001 48000008 894d0932 714a0001 39400008 408225fc 718a4000 7c2a0b78 3821fcf0 41c20008 e82d0910 <0981fcf0> f92101a0 f9610170 f9810178 ---[ end trace a5dbd1f5ea4ccc51 ]--- Fixes: 0a882e28468f4 ("powerpc/64s/exception: remove bad stack branch") Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211004145642.1331214-2-npiggin@gmail.com 
Emergency stack path was jumping into a 3: label inside the
__GEN_COMMON_BODY macro for the normal path after it had finished,
rather than jumping over it. By a small miracle this is the correct
place to build up a new interrupt frame with the existing stack
pointer, so things basically worked okay with an added weird looking
700 trap frame on top (which had the wrong ->nip so it didn't decode
bug messages either).

Fix this by avoiding using numeric labels when jumping over non-trivial
macros.

Before:

 LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV
 Modules linked in:
 CPU: 0 PID: 88 Comm: sh Not tainted 5.15.0-rc2-00034-ge057cdade6e5 #2637
 NIP:  7265677368657265 LR: c00000000006c0c8 CTR: c0000000000097f0
 REGS: c0000000fffb3a50 TRAP: 0700   Not tainted
 MSR:  9000000000021031 <SF,HV,ME,IR,DR,LE>  CR: 00000700  XER: 20040000
 CFAR: c0000000000098b0 IRQMASK: 0
 GPR00: c00000000006c964 c0000000fffb3cf0 c000000001513800 0000000000000000
 GPR04: 0000000048ab0778 0000000042000000 0000000000000000 0000000000001299
 GPR08: 000001e447c718ec 0000000022424282 0000000000002710 c00000000006bee8
 GPR12: 9000000000009033 c0000000016b0000 00000000000000b0 0000000000000001
 GPR16: 0000000000000000 0000000000000002 0000000000000000 0000000000000ff8
 GPR20: 0000000000001fff 0000000000000007 0000000000000080 00007fff89d90158
 GPR24: 0000000002000000 0000000002000000 0000000000000255 0000000000000300
 GPR28: c000000001270000 0000000042000000 0000000048ab0778 c000000080647e80
 NIP [7265677368657265] 0x7265677368657265
 LR [c00000000006c0c8] ___do_page_fault+0x3f8/0xb10
 Call Trace:
 [c0000000fffb3cf0] [c00000000000bdac] soft_nmi_common+0x13c/0x1d0 (unreliable)
 --- interrupt: 700 at decrementer_common_virt+0xb8/0x230
 NIP:  c0000000000098b8 LR: c00000000006c0c8 CTR: c0000000000097f0
 REGS: c0000000fffb3d60 TRAP: 0700   Not tainted
 MSR:  9000000000021031 <SF,HV,ME,IR,DR,LE>  CR: 22424282  XER: 20040000
 CFAR: c0000000000098b0 IRQMASK: 0
 GPR00: c00000000006c964 0000000000002400 c000000001513800 0000000000000000
 GPR04: 0000000048ab0778 0000000042000000 0000000000000000 0000000000001299
 GPR08: 000001e447c718ec 0000000022424282 0000000000002710 c00000000006bee8
 GPR12: 9000000000009033 c0000000016b0000 00000000000000b0 0000000000000001
 GPR16: 0000000000000000 0000000000000002 0000000000000000 0000000000000ff8
 GPR20: 0000000000001fff 0000000000000007 0000000000000080 00007fff89d90158
 GPR24: 0000000002000000 0000000002000000 0000000000000255 0000000000000300
 GPR28: c000000001270000 0000000042000000 0000000048ab0778 c000000080647e80
 NIP [c0000000000098b8] decrementer_common_virt+0xb8/0x230
 LR [c00000000006c0c8] ___do_page_fault+0x3f8/0xb10
 --- interrupt: 700
 Instruction dump:
 XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
 XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
 ---[ end trace 6d28218e0cc3c949 ]---

After:

 ------------[ cut here ]------------
 kernel BUG at arch/powerpc/kernel/exceptions-64s.S:491!
 Oops: Exception in kernel mode, sig: 5 [#1]
 LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV
 Modules linked in:
 CPU: 0 PID: 88 Comm: login Not tainted 5.15.0-rc2-00034-ge057cdade6e5-dirty #2638
 NIP:  c0000000000098b8 LR: c00000000006bf04 CTR: c0000000000097f0
 REGS: c0000000fffb3d60 TRAP: 0700   Not tainted
 MSR:  9000000000021031 <SF,HV,ME,IR,DR,LE>  CR: 24482227  XER: 00040000
 CFAR: c0000000000098b0 IRQMASK: 0
 GPR00: c00000000006bf04 0000000000002400 c000000001513800 c000000001271868
 GPR04: 00000000100f0d29 0000000042000000 0000000000000007 0000000000000009
 GPR08: 00000000100f0d29 0000000024482227 0000000000002710 c000000000181b3c
 GPR12: 9000000000009033 c0000000016b0000 00000000100f0d29 c000000005b22f00
 GPR16: 00000000ffff0000 0000000000000001 0000000000000009 00000000100eed90
 GPR20: 00000000100eed90 0000000010000000 000000001000a49c 00000000100f1430
 GPR24: c000000001271868 0000000002000000 0000000000000215 0000000000000300
 GPR28: c000000001271800 0000000042000000 00000000100f0d29 c000000080647860
 NIP [c0000000000098b8] decrementer_common_virt+0xb8/0x230
 LR [c00000000006bf04] ___do_page_fault+0x234/0xb10
 Call Trace:
 Instruction dump:
 4182000c 39400001 48000008 894d0932 714a0001 39400008 408225fc 718a4000
 7c2a0b78 3821fcf0 41c20008 e82d0910 <0981fcf0> f92101a0 f9610170 f9810178
 ---[ end trace a5dbd1f5ea4ccc51 ]---

Fixes: 0a882e28468f4 ("powerpc/64s/exception: remove bad stack branch")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211004145642.1331214-2-npiggin@gmail.com
powerpc/security: Add a helper to query stf_barrier type 2021-10-07T08:52:58+00:00 Naveen N. Rao naveen.n.rao@linux.vnet.ibm.com 2021-10-05T20:25:24+00:00 030905920f32e91a52794937f67434ac0b3ea41a Add a helper to return the stf_barrier type for the current processor. Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/3bd5d7f96ea1547991ac2ce3137dc2b220bae285.1633464148.git.naveen.n.rao@linux.vnet.ibm.com 
Add a helper to return the stf_barrier type for the current processor.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/3bd5d7f96ea1547991ac2ce3137dc2b220bae285.1633464148.git.naveen.n.rao@linux.vnet.ibm.com
powerpc/iommu: Report the correct most efficient DMA mask for PCI devices 2021-09-30T07:10:17+00:00 Alexey Kardashevskiy aik@ozlabs.ru 2021-09-30T03:44:54+00:00 23c216b335d1fbd716076e8263b54a714ea3cf0e According to dma-api.rst, the dma_get_required_mask() helper should return "the mask that the platform requires to operate efficiently". Which in the case of PPC64 means the bypass mask and not a mask from an IOMMU table which is shorter and slower to use due to map/unmap operations (especially expensive on "pseries"). However the existing implementation ignores the possibility of bypassing and returns the IOMMU table mask on the pseries platform which makes some drivers (mpt3sas is one example) choose 32bit DMA even though bypass is supported. The powernv platform sort of handles it by having a bigger default window with a mask >=40 but it only works as drivers choose 63/64bit if the required mask is >32 which is rather pointless. This reintroduces the bypass capability check to let drivers make a better choice of the DMA mask. Fixes: f1565c24b596 ("powerpc: use the generic dma_ops_bypass mode") Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210930034454.95794-1-aik@ozlabs.ru 
According to dma-api.rst, the dma_get_required_mask() helper should return
"the mask that the platform requires to operate efficiently". Which in
the case of PPC64 means the bypass mask and not a mask from an IOMMU table
which is shorter and slower to use due to map/unmap operations (especially
expensive on "pseries").

However the existing implementation ignores the possibility of bypassing
and returns the IOMMU table mask on the pseries platform which makes some
drivers (mpt3sas is one example) choose 32bit DMA even though bypass is
supported. The powernv platform sort of handles it by having a bigger
default window with a mask >=40 but it only works as drivers choose
63/64bit if the required mask is >32 which is rather pointless.

This reintroduces the bypass capability check to let drivers make
a better choice of the DMA mask.

Fixes: f1565c24b596 ("powerpc: use the generic dma_ops_bypass mode")
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210930034454.95794-1-aik@ozlabs.ru