<feed xmlns='http://www.w3.org/2005/Atom'>
<title>user/sven/linux.git/arch/powerpc/sysdev, branch v5.5.8</title>
<subtitle>Linux Kernel
</subtitle>
<id>https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v5.5.8</id>
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<updated>2020-01-22T09:31:41Z</updated>
<entry>
<title>powerpc/xive: Discard ESB load value when interrupt is invalid</title>
<updated>2020-01-22T09:31:41Z</updated>
<author>
<name>Frederic Barrat</name>
<email>fbarrat@linux.ibm.com</email>
</author>
<published>2020-01-13T13:01:18Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=17328f218fb760c9c6accc5b52494889243a6b98'/>
<id>urn:sha1:17328f218fb760c9c6accc5b52494889243a6b98</id>
<content type='text'>
A load on an ESB page returning all 1's means that the underlying
device has invalidated the access to the PQ state of the interrupt
through mmio. It may happen, for example when querying a PHB interrupt
while the PHB is in an error state.

In that case, we should consider the interrupt to be invalid when
checking its state in the irq_get_irqchip_state() handler.

Fixes: da15c03b047d ("powerpc/xive: Implement get_irqchip_state method for XIVE to fix shutdown race")
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Frederic Barrat &lt;fbarrat@linux.ibm.com&gt;
[clg: wrote a commit log, introduced XIVE_ESB_INVALID ]
Signed-off-by: Cédric Le Goater &lt;clg@kaod.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20200113130118.27969-1-clg@kaod.org
</content>
</entry>
<entry>
<title>powerpc/xive: Skip ioremap() of ESB pages for LSI interrupts</title>
<updated>2019-12-04T13:11:45Z</updated>
<author>
<name>Cédric Le Goater</name>
<email>clg@kaod.org</email>
</author>
<published>2019-12-03T16:36:42Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=b67a95f2abff0c34e5667c15ab8900de73d8d087'/>
<id>urn:sha1:b67a95f2abff0c34e5667c15ab8900de73d8d087</id>
<content type='text'>
The PCI INTx interrupts and other LSI interrupts are handled differently
under a sPAPR platform. When the interrupt source characteristics are
queried, the hypervisor returns an H_INT_ESB flag to inform the OS
that it should be using the H_INT_ESB hcall for interrupt management
and not loads and stores on the interrupt ESB pages.

A default -1 value is returned for the addresses of the ESB pages. The
driver ignores this condition today and performs a bogus IO mapping.
Recent changes and the DEBUG_VM configuration option make the bug
visible with :

  kernel BUG at arch/powerpc/include/asm/book3s/64/pgtable.h:612!
  Oops: Exception in kernel mode, sig: 5 [#1]
  LE PAGE_SIZE=64K MMU=Radix MMU=Hash SMP NR_CPUS=1024 NUMA pSeries
  Modules linked in:
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.0-0.rc6.git0.1.fc32.ppc64le #1
  NIP:  c000000000f63294 LR: c000000000f62e44 CTR: 0000000000000000
  REGS: c0000000fa45f0d0 TRAP: 0700   Not tainted  (5.4.0-0.rc6.git0.1.fc32.ppc64le)
  ...
  NIP ioremap_page_range+0x4c4/0x6e0
  LR  ioremap_page_range+0x74/0x6e0
  Call Trace:
    ioremap_page_range+0x74/0x6e0 (unreliable)
    do_ioremap+0x8c/0x120
    __ioremap_caller+0x128/0x140
    ioremap+0x30/0x50
    xive_spapr_populate_irq_data+0x170/0x260
    xive_irq_domain_map+0x8c/0x170
    irq_domain_associate+0xb4/0x2d0
    irq_create_mapping+0x1e0/0x3b0
    irq_create_fwspec_mapping+0x27c/0x3e0
    irq_create_of_mapping+0x98/0xb0
    of_irq_parse_and_map_pci+0x168/0x230
    pcibios_setup_device+0x88/0x250
    pcibios_setup_bus_devices+0x54/0x100
    __of_scan_bus+0x160/0x310
    pcibios_scan_phb+0x330/0x390
    pcibios_init+0x8c/0x128
    do_one_initcall+0x60/0x2c0
    kernel_init_freeable+0x290/0x378
    kernel_init+0x2c/0x148
    ret_from_kernel_thread+0x5c/0x80

Fixes: bed81ee181dd ("powerpc/xive: introduce H_INT_ESB hcall")
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Cédric Le Goater &lt;clg@kaod.org&gt;
Tested-by: Daniel Axtens &lt;dja@axtens.net&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20191203163642.2428-1-clg@kaod.org
</content>
</entry>
<entry>
<title>Merge tag 'powerpc-5.5-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux</title>
<updated>2019-11-30T22:35:43Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-11-30T22:35:43Z</published>
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<id>urn:sha1:7794b1d4185e2587af46435e3e2f6696dae314c7</id>
<content type='text'>
Pull powerpc updates from Michael Ellerman:
 "Highlights:

   - Infrastructure for secure boot on some bare metal Power9 machines.
     The firmware support is still in development, so the code here
     won't actually activate secure boot on any existing systems.

   - A change to xmon (our crash handler / pseudo-debugger) to restrict
     it to read-only mode when the kernel is lockdown'ed, otherwise it's
     trivial to drop into xmon and modify kernel data, such as the
     lockdown state.

   - Support for KASLR on 32-bit BookE machines (Freescale / NXP).

   - Fixes for our flush_icache_range() and __kernel_sync_dicache()
     (VDSO) to work with memory ranges &gt;4GB.

   - Some reworks of the pseries CMM (Cooperative Memory Management)
     driver to make it behave more like other balloon drivers and enable
     some cleanups of generic mm code.

   - A series of fixes to our hardware breakpoint support to properly
     handle unaligned watchpoint addresses.

  Plus a bunch of other smaller improvements, fixes and cleanups.

  Thanks to: Alastair D'Silva, Andrew Donnellan, Aneesh Kumar K.V,
  Anthony Steinhauser, Cédric Le Goater, Chris Packham, Chris Smart,
  Christophe Leroy, Christopher M. Riedl, Christoph Hellwig, Claudio
  Carvalho, Daniel Axtens, David Hildenbrand, Deb McLemore, Diana
  Craciun, Eric Richter, Geert Uytterhoeven, Greg Kroah-Hartman, Greg
  Kurz, Gustavo L. F. Walbon, Hari Bathini, Harish, Jason Yan, Krzysztof
  Kozlowski, Leonardo Bras, Mathieu Malaterre, Mauro S. M. Rodrigues,
  Michal Suchanek, Mimi Zohar, Nathan Chancellor, Nathan Lynch, Nayna
  Jain, Nick Desaulniers, Oliver O'Halloran, Qian Cai, Rasmus Villemoes,
  Ravi Bangoria, Sam Bobroff, Santosh Sivaraj, Scott Wood, Thomas Huth,
  Tyrel Datwyler, Vaibhav Jain, Valentin Longchamp, YueHaibing"

* tag 'powerpc-5.5-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (144 commits)
  powerpc/fixmap: fix crash with HIGHMEM
  x86/efi: remove unused variables
  powerpc: Define arch_is_kernel_initmem_freed() for lockdep
  powerpc/prom_init: Use -ffreestanding to avoid a reference to bcmp
  powerpc: Avoid clang warnings around setjmp and longjmp
  powerpc: Don't add -mabi= flags when building with Clang
  powerpc: Fix Kconfig indentation
  powerpc/fixmap: don't clear fixmap area in paging_init()
  selftests/powerpc: spectre_v2 test must be built 64-bit
  powerpc/powernv: Disable native PCIe port management
  powerpc/kexec: Move kexec files into a dedicated subdir.
  powerpc/32: Split kexec low level code out of misc_32.S
  powerpc/sysdev: drop simple gpio
  powerpc/83xx: map IMMR with a BAT.
  powerpc/32s: automatically allocate BAT in setbat()
  powerpc/ioremap: warn on early use of ioremap()
  powerpc: Add support for GENERIC_EARLY_IOREMAP
  powerpc/fixmap: Use __fix_to_virt() instead of fix_to_virt()
  powerpc/8xx: use the fixmapped IMMR in cpm_reset()
  powerpc/8xx: add __init to cpm1 init functions
  ...
</content>
</entry>
<entry>
<title>dma-mapping: treat dev-&gt;bus_dma_mask as a DMA limit</title>
<updated>2019-11-21T17:14:35Z</updated>
<author>
<name>Nicolas Saenz Julienne</name>
<email>nsaenzjulienne@suse.de</email>
</author>
<published>2019-11-21T09:26:44Z</published>
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<id>urn:sha1:a7ba70f1787f977f970cd116076c6fce4b9e01cc</id>
<content type='text'>
Using a mask to represent bus DMA constraints has a set of limitations.
The biggest one being it can only hold a power of two (minus one). The
DMA mapping code is already aware of this and treats dev-&gt;bus_dma_mask
as a limit. This quirk is already used by some architectures although
still rare.

With the introduction of the Raspberry Pi 4 we've found a new contender
for the use of bus DMA limits, as its PCIe bus can only address the
lower 3GB of memory (of a total of 4GB). This is impossible to represent
with a mask. To make things worse the device-tree code rounds non power
of two bus DMA limits to the next power of two, which is unacceptable in
this case.

In the light of this, rename dev-&gt;bus_dma_mask to dev-&gt;bus_dma_limit all
over the tree and treat it as such. Note that dev-&gt;bus_dma_limit should
contain the higher accessible DMA address.

Signed-off-by: Nicolas Saenz Julienne &lt;nsaenzjulienne@suse.de&gt;
Reviewed-by: Robin Murphy &lt;robin.murphy@arm.com&gt;
Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
</content>
</entry>
<entry>
<title>powerpc/sysdev: drop simple gpio</title>
<updated>2019-11-21T04:41:34Z</updated>
<author>
<name>Christophe Leroy</name>
<email>christophe.leroy@c-s.fr</email>
</author>
<published>2019-10-31T13:47:30Z</published>
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<id>urn:sha1:8795a739e5c72abeec51caf36b6df2b37e5720c5</id>
<content type='text'>
There is a config item CONFIG_SIMPLE_GPIO which
provides simple memory mapped GPIOs specific to powerpc.

However, the only platform which selects this option is
mpc5200, and this platform doesn't use it.

There are three boards calling simple_gpiochip_init(), but
as they don't select CONFIG_SIMPLE_GPIO, this is just a nop.

Simple_gpio is just redundant with the generic MMIO GPIO
driver which can be found in driver/gpio/ and selected via
CONFIG_GPIO_GENERIC_PLATFORM, so drop simple_gpio driver.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@c-s.fr&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/bf930402613b41b42d0441b784e0cc43fc18d1fb.1572529632.git.christophe.leroy@c-s.fr
</content>
</entry>
<entry>
<title>powerpc/xive: Prevent page fault issues in the machine crash handler</title>
<updated>2019-11-13T05:58:10Z</updated>
<author>
<name>Cédric Le Goater</name>
<email>clg@kaod.org</email>
</author>
<published>2019-10-31T06:31:00Z</published>
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<id>urn:sha1:1ca3dec2b2dff9d286ce6cd64108bda0e98f9710</id>
<content type='text'>
When the machine crash handler is invoked, all interrupts are masked
but interrupts which have not been started yet do not have an ESB page
mapped in the Linux address space. This crashes the 'crash kexec'
sequence on sPAPR guests.

To fix, force the mapping of the ESB page when an interrupt is being
mapped in the Linux IRQ number space. This is done by setting the
initial state of the interrupt to OFF which is not necessarily the
case on PowerNV.

Fixes: 243e25112d06 ("powerpc/xive: Native exploitation of the XIVE interrupt controller")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Cédric Le Goater &lt;clg@kaod.org&gt;
Reviewed-by: Greg Kurz &lt;groug@kaod.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20191031063100.3864-1-clg@kaod.org
</content>
</entry>
<entry>
<title>KVM: PPC: Book3S HV: use smp_mb() when setting/clearing host_ipi flag</title>
<updated>2019-09-24T02:46:26Z</updated>
<author>
<name>Michael Roth</name>
<email>mdroth@linux.vnet.ibm.com</email>
</author>
<published>2019-09-11T22:31:55Z</published>
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<id>urn:sha1:3a83f677a6eeff65751b29e3648d7c69c3be83f3</id>
<content type='text'>
On a 2-socket Power9 system with 32 cores/128 threads (SMT4) and 1TB
of memory running the following guest configs:

  guest A:
    - 224GB of memory
    - 56 VCPUs (sockets=1,cores=28,threads=2), where:
      VCPUs 0-1 are pinned to CPUs 0-3,
      VCPUs 2-3 are pinned to CPUs 4-7,
      ...
      VCPUs 54-55 are pinned to CPUs 108-111

  guest B:
    - 4GB of memory
    - 4 VCPUs (sockets=1,cores=4,threads=1)

with the following workloads (with KSM and THP enabled in all):

  guest A:
    stress --cpu 40 --io 20 --vm 20 --vm-bytes 512M

  guest B:
    stress --cpu 4 --io 4 --vm 4 --vm-bytes 512M

  host:
    stress --cpu 4 --io 4 --vm 2 --vm-bytes 256M

the below soft-lockup traces were observed after an hour or so and
persisted until the host was reset (this was found to be reliably
reproducible for this configuration, for kernels 4.15, 4.18, 5.0,
and 5.3-rc5):

  [ 1253.183290] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1253.183319] rcu:     124-....: (5250 ticks this GP) idle=10a/1/0x4000000000000002 softirq=5408/5408 fqs=1941
  [ 1256.287426] watchdog: BUG: soft lockup - CPU#105 stuck for 23s! [CPU 52/KVM:19709]
  [ 1264.075773] watchdog: BUG: soft lockup - CPU#24 stuck for 23s! [worker:19913]
  [ 1264.079769] watchdog: BUG: soft lockup - CPU#31 stuck for 23s! [worker:20331]
  [ 1264.095770] watchdog: BUG: soft lockup - CPU#45 stuck for 23s! [worker:20338]
  [ 1264.131773] watchdog: BUG: soft lockup - CPU#64 stuck for 23s! [avocado:19525]
  [ 1280.408480] watchdog: BUG: soft lockup - CPU#124 stuck for 22s! [ksmd:791]
  [ 1316.198012] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1316.198032] rcu:     124-....: (21003 ticks this GP) idle=10a/1/0x4000000000000002 softirq=5408/5408 fqs=8243
  [ 1340.411024] watchdog: BUG: soft lockup - CPU#124 stuck for 22s! [ksmd:791]
  [ 1379.212609] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1379.212629] rcu:     124-....: (36756 ticks this GP) idle=10a/1/0x4000000000000002 softirq=5408/5408 fqs=14714
  [ 1404.413615] watchdog: BUG: soft lockup - CPU#124 stuck for 22s! [ksmd:791]
  [ 1442.227095] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1442.227115] rcu:     124-....: (52509 ticks this GP) idle=10a/1/0x4000000000000002 softirq=5408/5408 fqs=21403
  [ 1455.111787] INFO: task worker:19907 blocked for more than 120 seconds.
  [ 1455.111822]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.111833] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.111884] INFO: task worker:19908 blocked for more than 120 seconds.
  [ 1455.111905]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.111925] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.111966] INFO: task worker:20328 blocked for more than 120 seconds.
  [ 1455.111986]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.111998] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112048] INFO: task worker:20330 blocked for more than 120 seconds.
  [ 1455.112068]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.112097] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112138] INFO: task worker:20332 blocked for more than 120 seconds.
  [ 1455.112159]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.112179] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112210] INFO: task worker:20333 blocked for more than 120 seconds.
  [ 1455.112231]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.112242] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112282] INFO: task worker:20335 blocked for more than 120 seconds.
  [ 1455.112303]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.112332] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112372] INFO: task worker:20336 blocked for more than 120 seconds.
  [ 1455.112392]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1

CPUs 45, 24, and 124 are stuck on spin locks, likely held by
CPUs 105 and 31.

CPUs 105 and 31 are stuck in smp_call_function_many(), waiting on
target CPU 42. For instance:

  # CPU 105 registers (via xmon)
  R00 = c00000000020b20c   R16 = 00007d1bcd800000
  R01 = c00000363eaa7970   R17 = 0000000000000001
  R02 = c0000000019b3a00   R18 = 000000000000006b
  R03 = 000000000000002a   R19 = 00007d537d7aecf0
  R04 = 000000000000002a   R20 = 60000000000000e0
  R05 = 000000000000002a   R21 = 0801000000000080
  R06 = c0002073fb0caa08   R22 = 0000000000000d60
  R07 = c0000000019ddd78   R23 = 0000000000000001
  R08 = 000000000000002a   R24 = c00000000147a700
  R09 = 0000000000000001   R25 = c0002073fb0ca908
  R10 = c000008ffeb4e660   R26 = 0000000000000000
  R11 = c0002073fb0ca900   R27 = c0000000019e2464
  R12 = c000000000050790   R28 = c0000000000812b0
  R13 = c000207fff623e00   R29 = c0002073fb0ca808
  R14 = 00007d1bbee00000   R30 = c0002073fb0ca800
  R15 = 00007d1bcd600000   R31 = 0000000000000800
  pc  = c00000000020b260 smp_call_function_many+0x3d0/0x460
  cfar= c00000000020b270 smp_call_function_many+0x3e0/0x460
  lr  = c00000000020b20c smp_call_function_many+0x37c/0x460
  msr = 900000010288b033   cr  = 44024824
  ctr = c000000000050790   xer = 0000000000000000   trap =  100

CPU 42 is running normally, doing VCPU work:

  # CPU 42 stack trace (via xmon)
  [link register   ] c00800001be17188 kvmppc_book3s_radix_page_fault+0x90/0x2b0 [kvm_hv]
  [c000008ed3343820] c000008ed3343850 (unreliable)
  [c000008ed33438d0] c00800001be11b6c kvmppc_book3s_hv_page_fault+0x264/0xe30 [kvm_hv]
  [c000008ed33439d0] c00800001be0d7b4 kvmppc_vcpu_run_hv+0x8dc/0xb50 [kvm_hv]
  [c000008ed3343ae0] c00800001c10891c kvmppc_vcpu_run+0x34/0x48 [kvm]
  [c000008ed3343b00] c00800001c10475c kvm_arch_vcpu_ioctl_run+0x244/0x420 [kvm]
  [c000008ed3343b90] c00800001c0f5a78 kvm_vcpu_ioctl+0x470/0x7c8 [kvm]
  [c000008ed3343d00] c000000000475450 do_vfs_ioctl+0xe0/0xc70
  [c000008ed3343db0] c0000000004760e4 ksys_ioctl+0x104/0x120
  [c000008ed3343e00] c000000000476128 sys_ioctl+0x28/0x80
  [c000008ed3343e20] c00000000000b388 system_call+0x5c/0x70
  --- Exception: c00 (System Call) at 00007d545cfd7694
  SP (7d53ff7edf50) is in userspace

It was subsequently found that ipi_message[PPC_MSG_CALL_FUNCTION]
was set for CPU 42 by at least 1 of the CPUs waiting in
smp_call_function_many(), but somehow the corresponding
call_single_queue entries were never processed by CPU 42, causing the
callers to spin in csd_lock_wait() indefinitely.

Nick Piggin suggested something similar to the following sequence as
a possible explanation (interleaving of CALL_FUNCTION/RESCHEDULE
IPI messages seems to be most common, but any mix of CALL_FUNCTION and
!CALL_FUNCTION messages could trigger it):

    CPU
      X: smp_muxed_ipi_set_message():
      X:   smp_mb()
      X:   message[RESCHEDULE] = 1
      X: doorbell_global_ipi(42):
      X:   kvmppc_set_host_ipi(42, 1)
      X:   ppc_msgsnd_sync()/smp_mb()
      X:   ppc_msgsnd() -&gt; 42
     42: doorbell_exception(): // from CPU X
     42:   ppc_msgsync()
    105: smp_muxed_ipi_set_message():
    105:   smb_mb()
         // STORE DEFERRED DUE TO RE-ORDERING
  --105:   message[CALL_FUNCTION] = 1
  | 105: doorbell_global_ipi(42):
  | 105:   kvmppc_set_host_ipi(42, 1)
  |  42:   kvmppc_set_host_ipi(42, 0)
  |  42: smp_ipi_demux_relaxed()
  |  42: // returns to executing guest
  |      // RE-ORDERED STORE COMPLETES
  -&gt;105:   message[CALL_FUNCTION] = 1
    105:   ppc_msgsnd_sync()/smp_mb()
    105:   ppc_msgsnd() -&gt; 42
     42: local_paca-&gt;kvm_hstate.host_ipi == 0 // IPI ignored
    105: // hangs waiting on 42 to process messages/call_single_queue

This can be prevented with an smp_mb() at the beginning of
kvmppc_set_host_ipi(), such that stores to message[&lt;type&gt;] (or other
state indicated by the host_ipi flag) are ordered vs. the store to
to host_ipi.

However, doing so might still allow for the following scenario (not
yet observed):

    CPU
      X: smp_muxed_ipi_set_message():
      X:   smp_mb()
      X:   message[RESCHEDULE] = 1
      X: doorbell_global_ipi(42):
      X:   kvmppc_set_host_ipi(42, 1)
      X:   ppc_msgsnd_sync()/smp_mb()
      X:   ppc_msgsnd() -&gt; 42
     42: doorbell_exception(): // from CPU X
     42:   ppc_msgsync()
         // STORE DEFERRED DUE TO RE-ORDERING
  -- 42:   kvmppc_set_host_ipi(42, 0)
  |  42: smp_ipi_demux_relaxed()
  | 105: smp_muxed_ipi_set_message():
  | 105:   smb_mb()
  | 105:   message[CALL_FUNCTION] = 1
  | 105: doorbell_global_ipi(42):
  | 105:   kvmppc_set_host_ipi(42, 1)
  |      // RE-ORDERED STORE COMPLETES
  -&gt; 42:   kvmppc_set_host_ipi(42, 0)
     42: // returns to executing guest
    105:   ppc_msgsnd_sync()/smp_mb()
    105:   ppc_msgsnd() -&gt; 42
     42: local_paca-&gt;kvm_hstate.host_ipi == 0 // IPI ignored
    105: // hangs waiting on 42 to process messages/call_single_queue

Fixing this scenario would require an smp_mb() *after* clearing
host_ipi flag in kvmppc_set_host_ipi() to order the store vs.
subsequent processing of IPI messages.

To handle both cases, this patch splits kvmppc_set_host_ipi() into
separate set/clear functions, where we execute smp_mb() prior to
setting host_ipi flag, and after clearing host_ipi flag. These
functions pair with each other to synchronize the sender and receiver
sides.

With that change in place the above workload ran for 20 hours without
triggering any lock-ups.

Fixes: 755563bc79c7 ("powerpc/powernv: Fixes for hypervisor doorbell handling") # v4.0
Signed-off-by: Michael Roth &lt;mdroth@linux.vnet.ibm.com&gt;
Acked-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190911223155.16045-1-mdroth@linux.vnet.ibm.com
</content>
</entry>
<entry>
<title>Merge tag 'powerpc-5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux</title>
<updated>2019-09-20T18:48:06Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-09-20T18:48:06Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=45824fc0da6e46cc5d563105e1eaaf3098a686f9'/>
<id>urn:sha1:45824fc0da6e46cc5d563105e1eaaf3098a686f9</id>
<content type='text'>
Pull powerpc updates from Michael Ellerman:
 "This is a bit late, partly due to me travelling, and partly due to a
  power outage knocking out some of my test systems *while* I was
  travelling.

   - Initial support for running on a system with an Ultravisor, which
     is software that runs below the hypervisor and protects guests
     against some attacks by the hypervisor.

   - Support for building the kernel to run as a "Secure Virtual
     Machine", ie. as a guest capable of running on a system with an
     Ultravisor.

   - Some changes to our DMA code on bare metal, to allow devices with
     medium sized DMA masks (&gt; 32 &amp;&amp; &lt; 59 bits) to use more than 2GB of
     DMA space.

   - Support for firmware assisted crash dumps on bare metal (powernv).

   - Two series fixing bugs in and refactoring our PCI EEH code.

   - A large series refactoring our exception entry code to use gas
     macros, both to make it more readable and also enable some future
     optimisations.

  As well as many cleanups and other minor features &amp; fixups.

  Thanks to: Adam Zerella, Alexey Kardashevskiy, Alistair Popple, Andrew
  Donnellan, Aneesh Kumar K.V, Anju T Sudhakar, Anshuman Khandual,
  Balbir Singh, Benjamin Herrenschmidt, Cédric Le Goater, Christophe
  JAILLET, Christophe Leroy, Christopher M. Riedl, Christoph Hellwig,
  Claudio Carvalho, Daniel Axtens, David Gibson, David Hildenbrand,
  Desnes A. Nunes do Rosario, Ganesh Goudar, Gautham R. Shenoy, Greg
  Kurz, Guerney Hunt, Gustavo Romero, Halil Pasic, Hari Bathini, Joakim
  Tjernlund, Jonathan Neuschafer, Jordan Niethe, Leonardo Bras, Lianbo
  Jiang, Madhavan Srinivasan, Mahesh Salgaonkar, Mahesh Salgaonkar,
  Masahiro Yamada, Maxiwell S. Garcia, Michael Anderson, Nathan
  Chancellor, Nathan Lynch, Naveen N. Rao, Nicholas Piggin, Oliver
  O'Halloran, Qian Cai, Ram Pai, Ravi Bangoria, Reza Arbab, Ryan Grimm,
  Sam Bobroff, Santosh Sivaraj, Segher Boessenkool, Sukadev Bhattiprolu,
  Thiago Bauermann, Thiago Jung Bauermann, Thomas Gleixner, Tom
  Lendacky, Vasant Hegde"

* tag 'powerpc-5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (264 commits)
  powerpc/mm/mce: Keep irqs disabled during lockless page table walk
  powerpc: Use ftrace_graph_ret_addr() when unwinding
  powerpc/ftrace: Enable HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
  ftrace: Look up the address of return_to_handler() using helpers
  powerpc: dump kernel log before carrying out fadump or kdump
  docs: powerpc: Add missing documentation reference
  powerpc/xmon: Fix output of XIVE IPI
  powerpc/xmon: Improve output of XIVE interrupts
  powerpc/mm/radix: remove useless kernel messages
  powerpc/fadump: support holes in kernel boot memory area
  powerpc/fadump: remove RMA_START and RMA_END macros
  powerpc/fadump: update documentation about option to release opalcore
  powerpc/fadump: consider f/w load area
  powerpc/opalcore: provide an option to invalidate /sys/firmware/opal/core file
  powerpc/opalcore: export /sys/firmware/opal/core for analysing opal crashes
  powerpc/fadump: update documentation about CONFIG_PRESERVE_FA_DUMP
  powerpc/fadump: add support to preserve crash data on FADUMP disabled kernel
  powerpc/fadump: improve how crashed kernel's memory is reserved
  powerpc/fadump: consider reserved ranges while releasing memory
  powerpc/fadump: make crash memory ranges array allocation generic
  ...
</content>
</entry>
<entry>
<title>powerpc/xmon: Fix output of XIVE IPI</title>
<updated>2019-09-13T14:58:47Z</updated>
<author>
<name>Cédric Le Goater</name>
<email>clg@kaod.org</email>
</author>
<published>2019-09-10T08:18:50Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=855d9140a394229f21fd4fd216f377ed45bd93a3'/>
<id>urn:sha1:855d9140a394229f21fd4fd216f377ed45bd93a3</id>
<content type='text'>
When dumping the XIVE state of an CPU IPI, xmon does not check if the
CPU is started or not which can cause an error. Add a check for that
and change the output to be on one line just as the XIVE interrupts of
the machine.

Signed-off-by: Cédric Le Goater &lt;clg@kaod.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190910081850.26038-3-clg@kaod.org
</content>
</entry>
<entry>
<title>powerpc/xmon: Improve output of XIVE interrupts</title>
<updated>2019-09-13T14:58:47Z</updated>
<author>
<name>Cédric Le Goater</name>
<email>clg@kaod.org</email>
</author>
<published>2019-09-10T08:18:49Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=5896163f7f91c0560cc41908c808661eee4c4121'/>
<id>urn:sha1:5896163f7f91c0560cc41908c808661eee4c4121</id>
<content type='text'>
When looping on the list of interrupts, add the current value of the
PQ bits with a load on the ESB page. This has the side effect of
faulting the ESB page of all interrupts.

Signed-off-by: Cédric Le Goater &lt;clg@kaod.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190910081850.26038-2-clg@kaod.org
</content>
</entry>
</feed>
