Commit Graph

107 Commits

Author SHA1 Message Date
Cédric Le Goater 3f601608b7 powerpc/xive: Fix error handling when allocating an IPI
This is a smatch warning:

  arch/powerpc/sysdev/xive/common.c:1161 xive_request_ipi() warn: unsigned 'xid->irq' is never less than zero.

Fixes: fd6db2892e ("powerpc/xive: Modernize XIVE-IPI domain with an 'alloc' handler")
Cc: stable@vger.kernel.org # v5.13
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210701152412.1507612-1-clg@kaod.org
2021-07-05 22:23:25 +10:00
Marc Zyngier e37af8011a powerpc: Move the use of irq_domain_add_nomap() behind a config option
Only a handful of old PPC systems are still using the old 'nomap'
variant of the irqdomain library. Move the associated definitions
behind a configuration option, which will allow us to make some
more radical changes.

Signed-off-by: Marc Zyngier <maz@kernel.org>
2021-06-10 13:09:17 +01:00
Linus Torvalds d42f323a7d Merge branch 'akpm' (patches from Andrew)
Merge misc updates from Andrew Morton:
 "A few misc subsystems and some of MM.

  175 patches.

  Subsystems affected by this patch series: ia64, kbuild, scripts, sh,
  ocfs2, kfifo, vfs, kernel/watchdog, and mm (slab-generic, slub,
  kmemleak, debug, pagecache, msync, gup, memremap, memcg, pagemap,
  mremap, dma, sparsemem, vmalloc, documentation, kasan, initialization,
  pagealloc, and memory-failure)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (175 commits)
  mm/memory-failure: unnecessary amount of unmapping
  mm/mmzone.h: fix existing kernel-doc comments and link them to core-api
  mm: page_alloc: ignore init_on_free=1 for debug_pagealloc=1
  net: page_pool: use alloc_pages_bulk in refill code path
  net: page_pool: refactor dma_map into own function page_pool_dma_map
  SUNRPC: refresh rq_pages using a bulk page allocator
  SUNRPC: set rq_page_end differently
  mm/page_alloc: inline __rmqueue_pcplist
  mm/page_alloc: optimize code layout for __alloc_pages_bulk
  mm/page_alloc: add an array-based interface to the bulk page allocator
  mm/page_alloc: add a bulk page allocator
  mm/page_alloc: rename alloced to allocated
  mm/page_alloc: duplicate include linux/vmalloc.h
  mm, page_alloc: avoid page_to_pfn() in move_freepages()
  mm/Kconfig: remove default DISCONTIGMEM_MANUAL
  mm: page_alloc: dump migrate-failed pages
  mm/mempolicy: fix mpol_misplaced kernel-doc
  mm/mempolicy: rewrite alloc_pages_vma documentation
  mm/mempolicy: rewrite alloc_pages documentation
  mm/mempolicy: rename alloc_pages_current to alloc_pages
  ...
2021-04-30 14:38:01 -07:00
Nicholas Piggin 94f88d7b90 powerpc/xive: remove unnecessary unmap_kernel_range
iounmap will remove ptes.

Link: https://lkml.kernel.org/r/20210322021806.892164-4-npiggin@gmail.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Cédric Le Goater <clg@kaod.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-04-30 11:20:40 -07:00
Cédric Le Goater e9e16917bc powerpc/xive: Use the "ibm, chip-id" property only under PowerNV
The 'chip_id' field of the XIVE CPU structure is used to choose a
target for a source located on the same chip. For that, the XIVE
driver queries the chip identifier from the "ibm,chip-id" property
and compares it to a 'src_chip' field identifying the chip of a
source. This information is only available on the PowerNV platform,
'src_chip' being assigned to XIVE_INVALID_CHIP_ID under pSeries.

The "ibm,chip-id" property is also not available on all platforms. It
was first introduced on PowerNV and later, under QEMU for pSeries/KVM.
However, the property is not part of PAPR and does not exist under
pSeries/PowerVM.

Assign 'chip_id' to XIVE_INVALID_CHIP_ID by default and let the
PowerNV platform override the value with the "ibm,chip-id" property.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210413130352.1183267-1-clg@kaod.org
2021-04-17 10:40:51 +10:00
Cédric Le Goater fd6db2892e powerpc/xive: Modernize XIVE-IPI domain with an 'alloc' handler
Instead of calling irq_create_mapping() to map the IPI for a node,
introduce an 'alloc' handler. This is usually an extension to support
hierarchy irq_domains which is not exactly the case for XIVE-IPI
domain. However, we can now use the irq_domain_alloc_irqs() routine
which allocates the IRQ descriptor on the specified node, even better
for cache performance on multi node machines.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210331144514.892250-10-clg@kaod.org
2021-04-14 23:04:15 +10:00
Cédric Le Goater 7dcc37b3ef powerpc/xive: Map one IPI interrupt per node
ipistorm [*] can be used to benchmark the raw interrupt rate of an
interrupt controller by measuring the number of IPIs a system can
sustain. When applied to the XIVE interrupt controller of POWER9 and
POWER10 systems, a significant drop of the interrupt rate can be
observed when crossing the second node boundary.

This is due to the fact that a single IPI interrupt is used for all
CPUs of the system. The structure is shared and the cache line updates
impact greatly the traffic between nodes and the overall IPI
performance.

As a workaround, the impact can be reduced by deactivating the IRQ
lockup detector ("noirqdebug") which does a lot of accounting in the
Linux IRQ descriptor structure and is responsible for most of the
performance penalty.

As a fix, this proposal allocates an IPI interrupt per node, to be
shared by all CPUs of that node. It solves the scaling issue, the IRQ
lockup detector still has an impact but the XIVE interrupt rate scales
linearly. It also improves the "noirqdebug" case as showed in the
tables below.

 * P9 DD2.2 - 2s * 64 threads

                                               "noirqdebug"
                        Mint/s                    Mint/s
 chips  cpus      IPI/sys   IPI/chip       IPI/chip    IPI/sys
 --------------------------------------------------------------
 1      0-15     4.984023   4.875405       4.996536   5.048892
        0-31    10.879164  10.544040      10.757632  11.037859
        0-47    15.345301  14.688764      14.926520  15.310053
        0-63    17.064907  17.066812      17.613416  17.874511
 2      0-79    11.768764  21.650749      22.689120  22.566508
        0-95    10.616812  26.878789      28.434703  28.320324
        0-111   10.151693  31.397803      31.771773  32.388122
        0-127    9.948502  33.139336      34.875716  35.224548

 * P10 DD1 - 4s (not homogeneous) 352 threads

                                               "noirqdebug"
                        Mint/s                    Mint/s
 chips  cpus      IPI/sys   IPI/chip       IPI/chip    IPI/sys
 --------------------------------------------------------------
 1      0-15     2.409402   2.364108       2.383303   2.395091
        0-31     6.028325   6.046075       6.089999   6.073750
        0-47     8.655178   8.644531       8.712830   8.724702
        0-63    11.629652  11.735953      12.088203  12.055979
        0-79    14.392321  14.729959      14.986701  14.973073
        0-95    12.604158  13.004034      17.528748  17.568095
 2      0-111    9.767753  13.719831      19.968606  20.024218
        0-127    6.744566  16.418854      22.898066  22.995110
        0-143    6.005699  19.174421      25.425622  25.417541
        0-159    5.649719  21.938836      27.952662  28.059603
        0-175    5.441410  24.109484      31.133915  31.127996
 3      0-191    5.318341  24.405322      33.999221  33.775354
        0-207    5.191382  26.449769      36.050161  35.867307
        0-223    5.102790  29.356943      39.544135  39.508169
        0-239    5.035295  31.933051      42.135075  42.071975
        0-255    4.969209  34.477367      44.655395  44.757074
 4      0-271    4.907652  35.887016      47.080545  47.318537
        0-287    4.839581  38.076137      50.464307  50.636219
        0-303    4.786031  40.881319      53.478684  53.310759
        0-319    4.743750  43.448424      56.388102  55.973969
        0-335    4.709936  45.623532      59.400930  58.926857
        0-351    4.681413  45.646151      62.035804  61.830057

[*] https://github.com/antonblanchard/ipistorm

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210331144514.892250-9-clg@kaod.org
2021-04-14 23:04:15 +10:00
Cédric Le Goater 33e4bc5946 powerpc/xive: Fix xmon command "dxi"
When under xmon, the "dxi" command dumps the state of the XIVE
interrupts. If an interrupt number is specified, only the state of
the associated XIVE interrupt is dumped. This form of the command
lacks an irq_data parameter which is nevertheless used by
xmon_xive_get_irq_config(), leading to an xmon crash.

Fix that by doing a lookup in the system IRQ mapping to query the IRQ
descriptor data. Invalid interrupt numbers, or not belonging to the
XIVE IRQ domain, OPAL event interrupt number for instance, should be
caught by the previous query done at the firmware level.

Fixes: 97ef275077 ("powerpc/xive: Fix xmon support on the PowerNV platform")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Tested-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210331144514.892250-8-clg@kaod.org
2021-04-14 23:04:15 +10:00
Cédric Le Goater 6bf66eb8f4 powerpc/xive: Simplify the dump of XIVE interrupts under xmon
Move the xmon routine under XIVE subsystem and rework the loop on the
interrupts taking into account the xive_irq_domain to filter out IPIs.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210331144514.892250-7-clg@kaod.org
2021-04-14 23:04:14 +10:00
Cédric Le Goater a74ce5926b powerpc/xive: Drop check on irq_data in xive_core_debug_show()
When looping on IRQ descriptor, irq_data is always valid.

Fixes: 930914b7d5 ("powerpc/xive: Add a debugfs file to dump internal XIVE state")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210331144514.892250-6-clg@kaod.org
2021-04-14 23:04:14 +10:00
Cédric Le Goater 5159d98728 powerpc/xive: Simplify xive_core_debug_show()
Now that the IPI interrupt has its own domain, the checks on the HW
interrupt number XIVE_IPI_HW_IRQ and on the chip can be replaced by a
check on the domain.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210331144514.892250-5-clg@kaod.org
2021-04-14 23:04:14 +10:00
Cédric Le Goater 1835e72942 powerpc/xive: Remove useless check on XIVE_IPI_HW_IRQ
The IPI interrupt has its own domain now. Testing the HW interrupt
number is not needed anymore.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210331144514.892250-4-clg@kaod.org
2021-04-14 23:04:14 +10:00
Cédric Le Goater 7d34849413 powerpc/xive: Introduce an IPI interrupt domain
The IPI interrupt is a special case of the XIVE IRQ domain. When
mapping and unmapping the interrupts in the Linux interrupt number
space, the HW interrupt number 0 (XIVE_IPI_HW_IRQ) is checked to
distinguish the IPI interrupt from other interrupts of the system.

Simplify the XIVE interrupt domain by introducing a specific domain
for the IPI.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210331144514.892250-3-clg@kaod.org
2021-04-14 23:04:14 +10:00
Yang Li 9214cf0f48 powerpc/xive: use true and false for bool variable
fixed the following coccicheck:
./arch/powerpc/sysdev/xive/spapr.c:552:8-9: WARNING: return of 0/1 in
function 'xive_spapr_match' with return type bool

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1615793096-83758-1-git-send-email-yang.lee@linux.alibaba.com
2021-03-29 13:22:13 +11:00
Cédric Le Goater 07efbca11c powerpc/xive: Improve error reporting of OPAL calls
Introduce a vp_err() macro to standardize error reporting.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201210171450.1933725-13-clg@kaod.org
2020-12-11 09:53:11 +11:00
Cédric Le Goater 614546d562 powerpc/xive: Simplify xive_do_source_eoi()
Previous patches removed the need of the first argument which was a
hack for Firwmware EOI. Remove it and flatten the routine which has
became simpler.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201210171450.1933725-12-clg@kaod.org
2020-12-11 09:53:11 +11:00
Cédric Le Goater cf58b74666 powerpc/xive: Remove P9 DD1 flag XIVE_IRQ_FLAG_EOI_FW
This flag was used to support the P9 DD1 and we have stopped
supporting this CPU when DD2 came out. See skiboot commit:

  https://github.com/open-power/skiboot/commit/0b0d15e3c170

Also, remove eoi handler which is now unused.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201210171450.1933725-11-clg@kaod.org
2020-12-11 09:53:10 +11:00
Cédric Le Goater b5277d18c6 powerpc/xive: Remove P9 DD1 flag XIVE_IRQ_FLAG_MASK_FW
This flag was used to support the PHB4 LSIs on P9 DD1 and we have
stopped supporting this CPU when DD2 came out. See skiboot commit:

  https://github.com/open-power/skiboot/commit/0b0d15e3c170

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201210171450.1933725-10-clg@kaod.org
2020-12-11 09:53:10 +11:00
Cédric Le Goater 4cc0e36df2 powerpc/xive: Remove P9 DD1 flag XIVE_IRQ_FLAG_SHIFT_BUG
This flag was used to support the PHB4 LSIs on P9 DD1 and we have
stopped supporting this CPU when DD2 came out. See skiboot commit:

  https://github.com/open-power/skiboot/commit/0b0d15e3c170

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201210171450.1933725-9-clg@kaod.org
2020-12-11 09:53:10 +11:00
Cédric Le Goater a5021abc48 powerpc/xive: Add a debug_show handler to the XIVE irq_domain
Full state of the Linux interrupt descriptors can be dumped under
debugfs when compiled with CONFIG_GENERIC_IRQ_DEBUGFS. Add support for
the XIVE interrupt controller.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201210171450.1933725-7-clg@kaod.org
2020-12-11 09:53:10 +11:00
Cédric Le Goater 9dfe4b14df powerpc/xive: Add a name to the IRQ domain
We hope one day to handle multiple irq_domain in the XIVE driver.
Start simple by setting the name using the DT node.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201210171450.1933725-6-clg@kaod.org
2020-12-11 09:53:09 +11:00
Cédric Le Goater e2cf43d595 powerpc/xive: Introduce XIVE_IPI_HW_IRQ
The XIVE driver deals with CPU IPIs in a peculiar way. Each CPU has
its own XIVE IPI interrupt allocated at the HW level, for PowerNV, or
at the hypervisor level for pSeries. In practice, these interrupts are
not always used. pSeries/PowerVM prefers local doorbells for local
threads since they are faster. On PowerNV, global doorbells are also
preferred for the same reason.

The mapping in the Linux is reduced to a single interrupt using HW
interrupt number 0 and a custom irq_chip to handle EOI. This can cause
performance issues in some benchmark (ipistorm) on multichip systems.

Clarify the use of the 0 value, it will help in improving multichip
support.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201210171450.1933725-4-clg@kaod.org
2020-12-11 09:34:07 +11:00
Cédric Le Goater 4f1c3f7b08 powerpc/xive: Rename XIVE_IRQ_NO_EOI to show its a flag
This is a simple cleanup to identify easily all flags of the XIVE
interrupt structure. The interrupts flagged with XIVE_IRQ_FLAG_NO_EOI
are the escalations used to wake up vCPUs in KVM. They are handled
very differently from the rest.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201210171450.1933725-3-clg@kaod.org
2020-12-11 09:34:07 +11:00
Cédric Le Goater 2228f19cf9 powerpc/xive: Make debug routines static
This fixes a compile error with W=1.

CC      arch/powerpc/sysdev/xive/common.o
../arch/powerpc/sysdev/xive/common.c:1568:6: error: no previous prototype for ‘xive_debug_show_cpu’ [-Werror=missing-prototypes]
 void xive_debug_show_cpu(struct seq_file *m, int cpu)
      ^~~~~~~~~~~~~~~~~~~
../arch/powerpc/sysdev/xive/common.c:1602:6: error: no previous prototype for ‘xive_debug_show_irq’ [-Werror=missing-prototypes]
 void xive_debug_show_irq(struct seq_file *m, u32 hw_irq, struct irq_data *d)
      ^~~~~~~~~~~~~~~~~~~

Fixes: 930914b7d5 ("powerpc/xive: Add a debugfs file to dump internal XIVE state")
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914211007.2285999-5-clg@kaod.org
2020-09-18 20:05:25 +10:00
Vladis Dronov aff779515a powerpc: fix function annotations to avoid section mismatch warnings with gcc-10
Certain warnings are emitted for powerpc code when building with a gcc-10
toolset:

    WARNING: modpost: vmlinux.o(.text.unlikely+0x377c): Section mismatch in
    reference from the function remove_pmd_table() to the function
    .meminit.text:split_kernel_mapping()
    The function remove_pmd_table() references
    the function __meminit split_kernel_mapping().
    This is often because remove_pmd_table lacks a __meminit
    annotation or the annotation of split_kernel_mapping is wrong.

Add the appropriate __init and __meminit annotations to make modpost not
complain. In all the cases there are just a single callsite from another
__init or __meminit function:

__meminit remove_pagetable() -> remove_pud_table() -> remove_pmd_table()
__init prom_init() -> setup_secure_guest()
__init xive_spapr_init() -> xive_spapr_disabled()

Signed-off-by: Vladis Dronov <vdronov@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200729133741.62789-1-vdronov@redhat.com
2020-07-30 10:50:07 +10:00
Alexey Kardashevskiy f0993c839e powerpc/xive: Ignore kmemleak false positives
xive_native_provision_pages() allocates memory and passes the pointer to
OPAL so kmemleak cannot find the pointer usage in the kernel memory and
produces a false positive report (below) (even if the kernel did scan
OPAL memory, it is unable to deal with __pa() addresses anyway).

This silences the warning.

unreferenced object 0xc000200350c40000 (size 65536):
  comm "qemu-system-ppc", pid 2725, jiffies 4294946414 (age 70776.530s)
  hex dump (first 32 bytes):
    02 00 00 00 50 00 00 00 00 00 00 00 00 00 00 00  ....P...........
    01 00 08 07 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<0000000081ff046c>] xive_native_alloc_vp_block+0x120/0x250
    [<00000000d555d524>] kvmppc_xive_compute_vp_id+0x248/0x350 [kvm]
    [<00000000d69b9c9f>] kvmppc_xive_connect_vcpu+0xc0/0x520 [kvm]
    [<000000006acbc81c>] kvm_arch_vcpu_ioctl+0x308/0x580 [kvm]
    [<0000000089c69580>] kvm_vcpu_ioctl+0x19c/0xae0 [kvm]
    [<00000000902ae91e>] ksys_ioctl+0x184/0x1b0
    [<00000000f3e68bd7>] sys_ioctl+0x48/0xb0
    [<0000000001b2c127>] system_call_exception+0x124/0x1f0
    [<00000000d2b2ee40>] system_call_common+0xe8/0x214

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200612043303.84894-1-aik@ozlabs.ru
2020-06-22 10:37:57 +10:00
Ram Pai 094235222d powerpc/xive: Share the event-queue page with the Hypervisor.
XIVE interrupt controller uses an Event Queue (EQ) to enqueue event
notifications when an exception occurs. The EQ is a single memory page
provided by the O/S defining a circular buffer, one per server and
priority couple.

On baremetal, the EQ page is configured with an OPAL call. On pseries,
an extra hop is necessary and the guest OS uses the hcall
H_INT_SET_QUEUE_CONFIG to configure the XIVE interrupt controller.

The XIVE controller being Hypervisor privileged, it will not be allowed
to enqueue event notifications for a Secure VM unless the EQ pages are
shared by the Secure VM.

Hypervisor/Ultravisor still requires support for the TIMA and ESB page
fault handlers. Until this is complete, QEMU can use the emulated XIVE
device for Secure VMs, option "kernel_irqchip=off" on the QEMU pseries
machine.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Reviewed-by: Cedric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200426020518.GC5853@oc0525413822.ibm.com
2020-05-28 23:24:40 +10:00
Cédric Le Goater 0755e85570 powerpc/xive: Do not expose a debugfs file when XIVE is disabled
The XIVE interrupt mode can be disabled with the "xive=off" kernel
parameter, in which case there is nothing to present to the user in the
associated /sys/kernel/debug/powerpc/xive file.

Fixes: 930914b7d5 ("powerpc/xive: Add a debugfs file to dump internal XIVE state")
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200429075122.1216388-4-clg@kaod.org
2020-05-28 23:24:32 +10:00
Cédric Le Goater a101950fcb powerpc/xive: Clear the page tables for the ESB IO mapping
Commit 1ca3dec2b2 ("powerpc/xive: Prevent page fault issues in the
machine crash handler") fixed an issue in the FW assisted dump of
machines using hash MMU and the XIVE interrupt mode under the POWER
hypervisor. It forced the mapping of the ESB page of interrupts being
mapped in the Linux IRQ number space to make sure the 'crash kexec'
sequence worked during such an event. But it didn't handle the
un-mapping.

This mapping is now blocking the removal of a passthrough IO adapter
under the POWER hypervisor because it expects the guest OS to have
cleared all page table entries related to the adapter. If some are
still present, the RTAS call which isolates the PCI slot returns error
9001 "valid outstanding translations".

Remove these mapping in the IRQ data cleanup routine.

Under KVM, this cleanup is not required because the ESB pages for the
adapter interrupts are un-mapped from the guest by the hypervisor in
the KVM XIVE native device. This is now redundant but it's harmless.

Fixes: 1ca3dec2b2 ("powerpc/xive: Prevent page fault issues in the machine crash handler")
Cc: stable@vger.kernel.org # v5.5+
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200429075122.1216388-2-clg@kaod.org
2020-05-26 23:37:14 +10:00
Michael Ellerman 787a2b682d Merge branch 'topic/ppc-kvm' into next
Merge our topic branch shared with the kvm-ppc tree.

This brings in one commit that touches the XIVE interrupt controller
logic across core and KVM code.
2020-05-20 23:38:13 +10:00
Cédric Le Goater b1f9be9392 powerpc/xive: Enforce load-after-store ordering when StoreEOI is active
When an interrupt has been handled, the OS notifies the interrupt
controller with a EOI sequence. On a POWER9 system using the XIVE
interrupt controller, this can be done with a load or a store
operation on the ESB interrupt management page of the interrupt. The
StoreEOI operation has less latency and improves interrupt handling
performance but it was deactivated during the POWER9 DD2.0 timeframe
because of ordering issues. We use the LoadEOI today but we plan to
reactivate StoreEOI in future architectures.

There is usually no need to enforce ordering between ESB load and
store operations as they should lead to the same result. E.g. a store
trigger and a load EOI can be executed in any order. Assuming the
interrupt state is PQ=10, a store trigger followed by a load EOI will
return a Q bit. In the reverse order, it will create a new interrupt
trigger from HW. In both cases, the handler processing interrupts is
notified.

In some cases, the XIVE_ESB_SET_PQ_10 load operation is used to
disable temporarily the interrupt source (mask/unmask). When the
source is reenabled, the OS can detect if interrupts were received
while the source was disabled and reinject them. This process needs
special care when StoreEOI is activated. The ESB load and store
operations should be correctly ordered because a XIVE_ESB_STORE_EOI
operation could leave the source enabled if it has not completed
before the loads.

For those cases, we enforce Load-after-Store ordering with a special
load operation offset. To avoid performance impact, this ordering is
only enforced when really needed, that is when interrupt sources are
temporarily disabled with the XIVE_ESB_SET_PQ_10 load. It should not
be needed for other loads.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200220081506.31209-1-clg@kaod.org
2020-05-07 22:58:31 +10:00
Haren Myneni 8d0ea29db5 powerpc/xive: Define xive_native_alloc_irq_on_chip()
This function allocates IRQ on a specific chip. VAS needs per chip
IRQ allocation and will have IRQ handler per VAS instance.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1587016720.2275.1047.camel@hbabu-laptop
2020-04-20 16:52:59 +10:00
Cédric Le Goater 930914b7d5 powerpc/xive: Add a debugfs file to dump internal XIVE state
As does XMON, the debugfs file /sys/kernel/debug/powerpc/xive exposes
the XIVE internal state of the machine CPUs and interrupts. Available
on the PowerNV and sPAPR platforms.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
[mpe: Make the debugfs file 0400]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200306150143.5551-5-clg@kaod.org
2020-03-27 00:20:38 +11:00
Cédric Le Goater 5191e0ba51 powerpc/xmon: Add source flags to output of XIVE interrupts
Some firmwares or hypervisors can advertise different source
characteristics. Track their value under XMON. What we are mostly
interested in is the StoreEOI flag.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200306150143.5551-4-clg@kaod.org
2020-03-27 00:19:05 +11:00
Cédric Le Goater 97ef275077 powerpc/xive: Fix xmon support on the PowerNV platform
The PowerNV platform has multiple IRQ chips and the xmon command
dumping the state of the XIVE interrupt should only operate on the
XIVE IRQ chip.

Fixes: 5896163f7f ("powerpc/xmon: Improve output of XIVE interrupts")
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200306150143.5551-3-clg@kaod.org
2020-03-27 00:19:05 +11:00
Cédric Le Goater b1a504a650 powerpc/xive: Use XIVE_BAD_IRQ instead of zero to catch non configured IPIs
When a CPU is brought up, an IPI number is allocated and recorded
under the XIVE CPU structure. Invalid IPI numbers are tracked with
interrupt number 0x0.

On the PowerNV platform, the interrupt number space starts at 0x10 and
this works fine. However, on the sPAPR platform, it is possible to
allocate the interrupt number 0x0 and this raises an issue when CPU 0
is unplugged. The XIVE spapr driver tracks allocated interrupt numbers
in a bitmask and it is not correctly updated when interrupt number 0x0
is freed. It stays allocated and it is then impossible to reallocate.

Fix by using the XIVE_BAD_IRQ value instead of zero on both platforms.

Reported-by: David Gibson <david@gibson.dropbear.id.au>
Fixes: eac1e731b5 ("powerpc/xive: guest exploitation of the XIVE interrupt controller")
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Tested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200306150143.5551-2-clg@kaod.org
2020-03-27 00:19:04 +11:00
Frederic Barrat 17328f218f powerpc/xive: Discard ESB load value when interrupt is invalid
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: da15c03b04 ("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 <fbarrat@linux.ibm.com>
[clg: wrote a commit log, introduced XIVE_ESB_INVALID ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200113130118.27969-1-clg@kaod.org
2020-01-22 20:31:41 +11:00
Cédric Le Goater b67a95f2ab powerpc/xive: Skip ioremap() of ESB pages for LSI interrupts
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: bed81ee181 ("powerpc/xive: introduce H_INT_ESB hcall")
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Tested-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191203163642.2428-1-clg@kaod.org
2019-12-05 00:11:45 +11:00
Cédric Le Goater 1ca3dec2b2 powerpc/xive: Prevent page fault issues in the machine crash handler
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: 243e25112d ("powerpc/xive: Native exploitation of the XIVE interrupt controller")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191031063100.3864-1-clg@kaod.org
2019-11-13 16:58:10 +11:00
Linus Torvalds 45824fc0da powerpc updates for 5.4
- 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 (> 32 && < 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 & 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.
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Merge tag 'powerpc-5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

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 (> 32 && < 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 & 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
  ...
2019-09-20 11:48:06 -07:00
Cédric Le Goater 855d9140a3 powerpc/xmon: Fix output of XIVE IPI
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 <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190910081850.26038-3-clg@kaod.org
2019-09-14 00:58:47 +10:00
Cédric Le Goater 5896163f7f powerpc/xmon: Improve output of XIVE interrupts
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 <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190910081850.26038-2-clg@kaod.org
2019-09-14 00:58:47 +10:00
Greg Kurz 6ccb4ac2bf powerpc/xive: Fix bogus error code returned by OPAL
There's a bug in skiboot that causes the OPAL_XIVE_ALLOCATE_IRQ call
to return the 32-bit value 0xffffffff when OPAL has run out of IRQs.
Unfortunatelty, OPAL return values are signed 64-bit entities and
errors are supposed to be negative. If that happens, the linux code
confusingly treats 0xffffffff as a valid IRQ number and panics at some
point.

A fix was recently merged in skiboot:

e97391ae2bb5 ("xive: fix return value of opal_xive_allocate_irq()")

but we need a workaround anyway to support older skiboots already
in the field.

Internally convert 0xffffffff to OPAL_RESOURCE which is the usual error
returned upon resource exhaustion.

Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821713818.1985334.14123187368108582810.stgit@bahia.lan
2019-09-12 09:27:05 +10:00
Paul Mackerras 2ad7a27dea KVM: PPC: Book3S: Enable XIVE native capability only if OPAL has required functions
There are some POWER9 machines where the OPAL firmware does not support
the OPAL_XIVE_GET_QUEUE_STATE and OPAL_XIVE_SET_QUEUE_STATE calls.
The impact of this is that a guest using XIVE natively will not be able
to be migrated successfully.  On the source side, the get_attr operation
on the KVM native device for the KVM_DEV_XIVE_GRP_EQ_CONFIG attribute
will fail; on the destination side, the set_attr operation for the same
attribute will fail.

This adds tests for the existence of the OPAL get/set queue state
functions, and if they are not supported, the XIVE-native KVM device
is not created and the KVM_CAP_PPC_IRQ_XIVE capability returns false.
Userspace can then either provide a software emulation of XIVE, or
else tell the guest that it does not have a XIVE controller available
to it.

Cc: stable@vger.kernel.org # v5.2+
Fixes: 3fab2d1058 ("KVM: PPC: Book3S HV: XIVE: Activate XIVE exploitation mode")
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
2019-08-27 11:45:49 +10:00
Cédric Le Goater b4868ff55d powerpc/xive: Fix dump of XIVE interrupt under pseries
The xmon 'dxi' command calls OPAL to query the XIVE configuration of a
interrupt. This can only be done on baremetal (PowerNV) and it will
crash a pseries machine.

Introduce a new XIVE get_irq_config() operation which implements a
different query depending on the platform, PowerNV or pseries, and
modify xmon to use a top level wrapper.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190814154754.23682-3-clg@kaod.org
2019-08-19 13:20:24 +10:00
Michael Ellerman 1a47908e0f Merge branch 'topic/ppc-kvm' into next
Merge our ppc-kvm topic branch. This contains several fixes for the XIVE
interrupt controller that we are sharing with the KVM tree.
2019-08-19 13:19:43 +10:00
Paul Mackerras da15c03b04 powerpc/xive: Implement get_irqchip_state method for XIVE to fix shutdown race
Testing has revealed the existence of a race condition where a XIVE
interrupt being shut down can be in one of the XIVE interrupt queues
(of which there are up to 8 per CPU, one for each priority) at the
point where free_irq() is called.  If this happens, can return an
interrupt number which has been shut down.  This can lead to various
symptoms:

- irq_to_desc(irq) can be NULL.  In this case, no end-of-interrupt
  function gets called, resulting in the CPU's elevated interrupt
  priority (numerically lowered CPPR) never gets reset.  That then
  means that the CPU stops processing interrupts, causing device
  timeouts and other errors in various device drivers.

- The irq descriptor or related data structures can be in the process
  of being freed as the interrupt code is using them.  This typically
  leads to crashes due to bad pointer dereferences.

This race is basically what commit 62e0468650 ("genirq: Add optional
hardware synchronization for shutdown", 2019-06-28) is intended to
fix, given a get_irqchip_state() method for the interrupt controller
being used.  It works by polling the interrupt controller when an
interrupt is being freed until the controller says it is not pending.

With XIVE, the PQ bits of the interrupt source indicate the state of
the interrupt source, and in particular the P bit goes from 0 to 1 at
the point where the hardware writes an entry into the interrupt queue
that this interrupt is directed towards.  Normally, the code will then
process the interrupt and do an end-of-interrupt (EOI) operation which
will reset PQ to 00 (assuming another interrupt hasn't been generated
in the meantime).  However, there are situations where the code resets
P even though a queue entry exists (for example, by setting PQ to 01,
which disables the interrupt source), and also situations where the
code leaves P at 1 after removing the queue entry (for example, this
is done for escalation interrupts so they cannot fire again until
they are explicitly re-enabled).

The code already has a 'saved_p' flag for the interrupt source which
indicates that a queue entry exists, although it isn't maintained
consistently.  This patch adds a 'stale_p' flag to indicate that
P has been left at 1 after processing a queue entry, and adds code
to set and clear saved_p and stale_p as necessary to maintain a
consistent indication of whether a queue entry may or may not exist.

With this, we can implement xive_get_irqchip_state() by looking at
stale_p, saved_p and the ESB PQ bits for the interrupt.

There is some additional code to handle escalation interrupts
properly; because they are enabled and disabled in KVM assembly code,
which does not have access to the xive_irq_data struct for the
escalation interrupt.  Hence, stale_p may be incorrect when the
escalation interrupt is freed in kvmppc_xive_{,native_}cleanup_vcpu().
Fortunately, we can fix it up by looking at vcpu->arch.xive_esc_on,
with some careful attention to barriers in order to ensure the correct
result if xive_esc_irq() races with kvmppc_xive_cleanup_vcpu().

Finally, this adds code to make noise on the console (pr_crit and
WARN_ON(1)) if we find an interrupt queue entry for an interrupt
which does not have a descriptor.  While this won't catch the race
reliably, if it does get triggered it will be an indication that
the race is occurring and needs to be debugged.

Fixes: 243e25112d ("powerpc/xive: Native exploitation of the XIVE interrupt controller")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190813100648.GE9567@blackberry
2019-08-16 14:16:59 +10:00
Christophe JAILLET fd3806562f powerpc/xive: Add a check for memory allocation failure
The result of this kzalloc is not checked. Add a check and corresponding
error handling code.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/cc53462734dfeaf15b6bad0e626b483de18656b4.1564647619.git.christophe.jaillet@wanadoo.fr
2019-08-15 22:52:55 +10:00
Christophe JAILLET b214a8f2ea powerpc/xive: Use GFP_KERNEL instead of GFP_ATOMIC in 'xive_irq_bitmap_add()'
There is no need to use GFP_ATOMIC here. GFP_KERNEL should be enough.
GFP_KERNEL is also already used for another allocation just a few lines
below.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/85d5d247ce753befd6aa63c473f7823de6520ccd.1564647619.git.christophe.jaillet@wanadoo.fr
2019-08-15 22:52:55 +10:00
Jordan Niethe 1ebe0dcce1 powerpc/xive: Update comment referencing magic loads from an ESB
The comment above xive_esb_read() references magic loads from an ESB as
described xive.h. This has been inaccurate since commit 12c1f339cd
("powerpc/xive: Move definition of ESB bits") which moved the
description. Update the comment to reference the new location of the
description in xive-regs.h

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Acked-by: Stewart Smith <stewart@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190802000835.26191-1-jniethe5@gmail.com
2019-08-05 18:53:04 +10:00