kernel/arch/powerpc/sysdev/xive/xive-internal.h, branch linux-rolling-stable

powerpc/xive: Fix compile when !CONFIG_PPC_POWERNV.

2021-12-01T23:40:38Z

The automatic "save & restore" of interrupt context is a POWER10/XIVE2 feature exploited by KVM under the PowerNV platform. It is not available under pSeries and the associated toggle should not be exposed under the XIVE debugfs directory. Introduce a platform handler for debugfs initialization and move the 'save-restore' entry under the native (PowerNV) backend to fix compile when !CONFIG_PPC_POWERNV. Fixes: 1e7684dc4fc7 ("powerpc/xive: Add a debugfs toggle for save-restore") Reported-by: kernel test robot Signed-off-by: Cédric Le Goater Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211201165418.1041842-1-clg@kaod.org

powerpc/xive: Add a debugfs toggle for save-restore

2021-11-25T00:25:31Z

On POWER10, the automatic "save & restore" of interrupt context is always available. Provide a way to deactivate it for tests or performance. Signed-off-by: Cédric Le Goater Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211105102636.1016378-11-clg@kaod.org

powerpc/xive: Use the "ibm, chip-id" property only under PowerNV

2021-04-17T00:40:51Z

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 Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210413130352.1183267-1-clg@kaod.org

powerpc/xive: Map one IPI interrupt per node

2021-04-14T13:04:15Z

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 Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210331144514.892250-9-clg@kaod.org

powerpc/xive: Remove P9 DD1 flag XIVE_IRQ_FLAG_EOI_FW

2020-12-10T22:53:10Z

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 Reviewed-by: Greg Kurz Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201210171450.1933725-11-clg@kaod.org

powerpc/xive: Add a name to the IRQ domain

2020-12-10T22:53:09Z

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 Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201210171450.1933725-6-clg@kaod.org

powerpc/xive: Introduce XIVE_IPI_HW_IRQ

2020-12-10T22:34:07Z

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 Reviewed-by: Greg Kurz Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201210171450.1933725-4-clg@kaod.org

powerpc/xive: Add a debugfs file to dump internal XIVE state

2020-03-26T13:20:38Z

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 [mpe: Make the debugfs file 0400] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200306150143.5551-5-clg@kaod.org

powerpc/xive: Use XIVE_BAD_IRQ instead of zero to catch non configured IPIs

2020-03-26T13:19:04Z

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 Fixes: eac1e731b59e ("powerpc/xive: guest exploitation of the XIVE interrupt controller") Cc: stable@vger.kernel.org # v4.14+ Signed-off-by: Cédric Le Goater Reviewed-by: David Gibson Tested-by: David Gibson Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200306150143.5551-2-clg@kaod.org

powerpc/xive: Fix dump of XIVE interrupt under pseries

2019-08-19T03:20:24Z

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 Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190814154754.23682-3-clg@kaod.org