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2020-05-19powerpc/xmon: Remove store_inst() for patch_instruction()Jordan Niethe
For modifying instructions in xmon, patch_instruction() can serve the same role that store_inst() is performing with the advantage of not being specific to xmon. In some places patch_instruction() is already being using followed by store_inst(). In these cases just remove the store_inst(). Otherwise replace store_inst() with patch_instruction(). Signed-off-by: Jordan Niethe <jniethe5@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Nicholas Piggin <npiggin@gmail.com> Link: https://lore.kernel.org/r/20200506034050.24806-2-jniethe5@gmail.com
2020-05-19powerpc/ps3: Fix kexec shutdown hangGeoff Levand
The ps3_mm_region_destroy() and ps3_mm_vas_destroy() routines are called very late in the shutdown via kexec's mmu_cleanup_all routine. By the time mmu_cleanup_all runs it is too late to use udbg_printf, and calling it will cause PS3 systems to hang. Remove all debugging statements from ps3_mm_region_destroy() and ps3_mm_vas_destroy() and replace any error reporting with calls to lv1_panic. With this change builds with 'DEBUG' defined will not cause kexec reboots to hang, and builds with 'DEBUG' defined or not will end in lv1_panic if an error is encountered. Signed-off-by: Geoff Levand <geoff@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/7325c4af2b4c989c19d6a26b90b1fec9c0615ddf.1589049250.git.geoff@infradead.org
2020-05-19ps3disk: use the default segment boundaryEmmanuel Nicolet
Since commit dcebd755926b ("block: use bio_for_each_bvec() to compute multi-page bvec count"), the kernel will bug_on on the PS3 because bio_split() is called with sectors == 0: kernel BUG at block/bio.c:1853! Oops: Exception in kernel mode, sig: 5 [#1] BE PAGE_SIZE=4K MMU=Hash PREEMPT SMP NR_CPUS=8 NUMA PS3 Modules linked in: firewire_sbp2 rtc_ps3(+) soundcore ps3_gelic(+) \ ps3rom(+) firewire_core ps3vram(+) usb_common crc_itu_t CPU: 0 PID: 97 Comm: blkid Not tainted 5.3.0-rc4 #1 NIP: c00000000027d0d0 LR: c00000000027d0b0 CTR: 0000000000000000 REGS: c00000000135ae90 TRAP: 0700 Not tainted (5.3.0-rc4) MSR: 8000000000028032 <SF,EE,IR,DR,RI> CR: 44008240 XER: 20000000 IRQMASK: 0 GPR00: c000000000289368 c00000000135b120 c00000000084a500 c000000004ff8300 GPR04: 0000000000000c00 c000000004c905e0 c000000004c905e0 000000000000ffff GPR08: 0000000000000000 0000000000000001 0000000000000000 000000000000ffff GPR12: 0000000000000000 c0000000008ef000 000000000000003e 0000000000080001 GPR16: 0000000000000100 000000000000ffff 0000000000000000 0000000000000004 GPR20: c00000000062fd7e 0000000000000001 000000000000ffff 0000000000000080 GPR24: c000000000781788 c00000000135b350 0000000000000080 c000000004c905e0 GPR28: c00000000135b348 c000000004ff8300 0000000000000000 c000000004c90000 NIP [c00000000027d0d0] .bio_split+0x28/0xac LR [c00000000027d0b0] .bio_split+0x8/0xac Call Trace: [c00000000135b120] [c00000000027d130] .bio_split+0x88/0xac (unreliable) [c00000000135b1b0] [c000000000289368] .__blk_queue_split+0x11c/0x53c [c00000000135b2d0] [c00000000028f614] .blk_mq_make_request+0x80/0x7d4 [c00000000135b3d0] [c000000000283a8c] .generic_make_request+0x118/0x294 [c00000000135b4b0] [c000000000283d34] .submit_bio+0x12c/0x174 [c00000000135b580] [c000000000205a44] .mpage_bio_submit+0x3c/0x4c [c00000000135b600] [c000000000206184] .mpage_readpages+0xa4/0x184 [c00000000135b750] [c0000000001ff8fc] .blkdev_readpages+0x24/0x38 [c00000000135b7c0] [c0000000001589f0] .read_pages+0x6c/0x1a8 [c00000000135b8b0] [c000000000158c74] .__do_page_cache_readahead+0x118/0x184 [c00000000135b9b0] [c0000000001591a8] .force_page_cache_readahead+0xe4/0xe8 [c00000000135ba50] [c00000000014fc24] .generic_file_read_iter+0x1d8/0x830 [c00000000135bb50] [c0000000001ffadc] .blkdev_read_iter+0x40/0x5c [c00000000135bbc0] [c0000000001b9e00] .new_sync_read+0x144/0x1a0 [c00000000135bcd0] [c0000000001bc454] .vfs_read+0xa0/0x124 [c00000000135bd70] [c0000000001bc7a4] .ksys_read+0x70/0xd8 [c00000000135be20] [c00000000000a524] system_call+0x5c/0x70 Instruction dump: 7fe3fb78 482e30dc 7c0802a6 482e3085 7c9e2378 f821ff71 7ca42b78 7d3e00d0 7c7d1b78 79290fe0 7cc53378 69290001 <0b090000> 81230028 7bca0020 7929ba62 [ end trace 313fec760f30aa1f ]--- The problem originates from setting the segment boundary of the request queue to -1UL. This makes get_max_segment_size() return zero when offset is zero, whatever the max segment size. The test with BLK_SEG_BOUNDARY_MASK fails and 'mask - (mask & offset) + 1' overflows to zero in the return statement. Not setting the segment boundary and using the default value (BLK_SEG_BOUNDARY_MASK) fixes the problem. Signed-off-by: Emmanuel Nicolet <emmanuel.nicolet@gmail.com> Signed-off-by: Geoff Levand <geoff@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/060a416c43138f45105c0540eff1a45539f7e2fc.1589049250.git.geoff@infradead.org
2020-05-19net/ps3_gelic_net: Remove duplicate error messageMarkus Elfring
Remove an extra message for a memory allocation failure in function gelic_descr_prepare_rx(). Signed-off-by: Markus Elfring <elfring@users.sourceforge.net> Signed-off-by: Geoff Levand <geoff@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/ba4bea4da97308c804fd3a0fae3773dde27b20ce.1589049250.git.geoff@infradead.org
2020-05-19drivers/ps3: Remove duplicate error messagesMarkus Elfring
Remove duplicate memory allocation failure error messages. Signed-off-by: Markus Elfring <elfring@users.sourceforge.net> Signed-off-by: Geoff Levand <geoff@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/c763425d8e6f680d3180b3246c9e77727df179d0.1589049250.git.geoff@infradead.org
2020-05-19powerpc/head_check: Avoid broken pipeGeoff Levand
Remove the '-m4' option to grep to allow grep to process all of nm's output. This avoids the nm warning: nm terminated with signal 13 [Broken pipe] Signed-off-by: Geoff Levand <geoff@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/872b6c84a4250ff140e476c62cabe9e56a02b6c2.1589049250.git.geoff@infradead.org
2020-05-19powerpc/wrapper: Output linker map fileGeoff Levand
To aid debugging wrapper troubles, output a linker map file 'wrapper.map' when the build is verbose. Signed-off-by: Geoff Levand <geoff@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/fb477f5e91c6b74a1dec98df3cc0a1c91632d94d.1589049250.git.geoff@infradead.org
2020-05-19powerpc/head_check: Automatic verbosityGeoff Levand
To aid debugging build problems turn on shell tracing for the head_check script when the build is verbose. Signed-off-by: Geoff Levand <geoff@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1ae1aed811ba6760af2e46d331285dd6a4de5b80.1589049250.git.geoff@infradead.org
2020-05-19powerpc/traps: Make unrecoverable NMIs die instead of panicNicholas Piggin
System Reset and Machine Check interrupts that are not recoverable due to being nested or interrupting when RI=0 currently panic. This is not necessary, and can often just kill the current context and recover. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> Link: https://lore.kernel.org/r/20200508043408.886394-16-npiggin@gmail.com
2020-05-19powerpc/traps: Do not trace system resetNicholas Piggin
Similarly to the previous patch, do not trace system reset. This code is used when there is a crash or hang, and tracing disturbs the system more and has been known to crash in the crash handling path. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Link: https://lore.kernel.org/r/20200508043408.886394-15-npiggin@gmail.com
2020-05-19powerpc/64s: machine check do not trace real-mode handlerNicholas Piggin
Rather than notrace annotations throughout a significant part of the machine check code across kernel/ pseries/ and powernv/ which can easily be broken and is infrequently tested, use paca->ftrace_enabled to blanket-disable tracing of the real-mode non-maskable handler. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Link: https://lore.kernel.org/r/20200508043408.886394-14-npiggin@gmail.com
2020-05-19powerpc: Implement ftrace_enabled() helpersNicholas Piggin
Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> Link: https://lore.kernel.org/r/20200508043408.886394-13-npiggin@gmail.com
2020-05-19powerpc/64s: machine check interrupt update NMI accountingNicholas Piggin
machine_check_early() is taken as an NMI, so nmi_enter() is used there. machine_check_exception() is no longer taken as an NMI (it's invoked via irq_work in the case a machine check hits in kernel mode), so remove the nmi_enter() from that case. In NMI context, hash faults don't try to refill the hash table, which can lead to crashes accessing non-pinned kernel pages. System reset still has this potential problem. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Drop change in show_regs() which breaks Book3E] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200508043408.886394-12-npiggin@gmail.com
2020-05-19powerpc/pseries: Machine check use rtas_call_unlocked() with args on stackNicholas Piggin
With the previous patch, machine checks can use rtas_call_unlocked() which avoids the RTAS spinlock which would deadlock if a machine check hits while making an RTAS call. This also avoids the complex RTAS error logging which has more RTAS calls and includes kmalloc (which can return memory beyond RMA, which would also crash). Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200508043408.886394-11-npiggin@gmail.com
2020-05-19powerpc/pseries: Limit machine check stack to 4GBNicholas Piggin
This allows rtas_args to be put on the machine check stack, which avoids a lot of complications with re-entrancy deadlocks. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com> Link: https://lore.kernel.org/r/20200508043408.886394-10-npiggin@gmail.com
2020-05-19powerpc/pseries/ras: fwnmi sreset should not interlockNicholas Piggin
PAPR does not specify that fwnmi sreset should be interlocked, and PowerVM (and therefore now QEMU) do not require it. These "ibm,nmi-interlock" calls are ignored by firmware, but there is a possibility that the sreset could have interrupted a machine check and release the machine check's interlock too early, corrupting it if another machine check came in. This is an extremely rare case, but it should be fixed for clarity and reducing the code executed in the sreset path. Firmware also does not provide error information for the sreset case to look at, so remove that comment. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Use __be64 to silence some sparse warnings] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200508043408.886394-9-npiggin@gmail.com
2020-05-18powerpc/pseries/ras: fwnmi avoid modifying r3 in error caseNicholas Piggin
If there is some error with the fwnmi save area, r3 has already been modified which doesn't help with debugging. Only update r3 when to restore the saved value. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200508043408.886394-8-npiggin@gmail.com
2020-05-18powerpc/pseries/ras: Fix FWNMI_VALID off by oneNicholas Piggin
This was discovered developing qemu fwnmi sreset support. This off-by-one bug means the last 16 bytes of the rtas area can not be used for a 16 byte save area. It's not a serious bug, and QEMU implementation has to retain a workaround for old kernels, but it's good to tighten it. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Acked-by: Mahesh Salgaonkar <mahesh@linux.ibm.com> Link: https://lore.kernel.org/r/20200508043408.886394-7-npiggin@gmail.com
2020-05-18powerpc/pseries/ras: Avoid calling rtas_token() in NMI pathsNicholas Piggin
In the interest of reducing code and possible failures in the machine check and system reset paths, grab the "ibm,nmi-interlock" token at init time. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com> Link: https://lore.kernel.org/r/20200508043408.886394-6-npiggin@gmail.com
2020-05-18powerpc/64s/exceptions: Machine check reconcile irq stateNicholas Piggin
pseries fwnmi machine check code pops the soft-irq checks in rtas_call (after the next patch to remove rtas_token from this call path). Rather than play whack a mole with these and forever having fragile code, it seems better to have the early machine check handler perform the same kind of reconcile as the other NMI interrupts. WARNING: CPU: 0 PID: 493 at arch/powerpc/kernel/irq.c:343 CPU: 0 PID: 493 Comm: a Tainted: G W NIP: c00000000001ed2c LR: c000000000042c40 CTR: 0000000000000000 REGS: c0000001fffd38b0 TRAP: 0700 Tainted: G W MSR: 8000000000021003 <SF,ME,RI,LE> CR: 28000488 XER: 00000000 CFAR: c00000000001ec90 IRQMASK: 0 GPR00: c000000000043820 c0000001fffd3b40 c0000000012ba300 0000000000000000 GPR04: 0000000048000488 0000000000000000 0000000000000000 00000000deadbeef GPR08: 0000000000000080 0000000000000000 0000000000000000 0000000000001001 GPR12: 0000000000000000 c0000000014a0000 0000000000000000 0000000000000000 GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR24: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR28: 0000000000000000 0000000000000001 c000000001360810 0000000000000000 NIP [c00000000001ed2c] arch_local_irq_restore.part.0+0xac/0x100 LR [c000000000042c40] unlock_rtas+0x30/0x90 Call Trace: [c0000001fffd3b40] [c000000001360810] 0xc000000001360810 (unreliable) [c0000001fffd3b60] [c000000000043820] rtas_call+0x1c0/0x280 [c0000001fffd3bb0] [c0000000000dc328] fwnmi_release_errinfo+0x38/0x70 [c0000001fffd3c10] [c0000000000dcd8c] pseries_machine_check_realmode+0x1dc/0x540 [c0000001fffd3cd0] [c00000000003fe04] machine_check_early+0x54/0x70 [c0000001fffd3d00] [c000000000008384] machine_check_early_common+0x134/0x1f0 --- interrupt: 200 at 0x13f1307c8 LR = 0x7fff888b8528 Instruction dump: 60000000 7d2000a6 71298000 41820068 39200002 7d210164 4bffff9c 60000000 60000000 7d2000a6 71298000 4c820020 <0fe00000> 4e800020 60000000 60000000 Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200508043408.886394-5-npiggin@gmail.com
2020-05-18powerpc/64s/exceptions: Change irq reconcile for NMIs from reusing _DAR to ↵Nicholas Piggin
RESULT A spare interrupt stack slot is needed to save irq state when reconciling NMIs (sreset and decrementer soft-nmi). _DAR is used for this, but we want to reconcile machine checks as well, which do use _DAR. Switch to using RESULT instead, as it's used by system calls. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200508043408.886394-4-npiggin@gmail.com
2020-05-18powerpc/64s/exceptions: Fix in_mce accounting in unrecoverable pathNicholas Piggin
Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Acked-by: Mahesh Salgaonkar <mahesh@linux.ibm.com> Link: https://lore.kernel.org/r/20200508043408.886394-3-npiggin@gmail.com
2020-05-18powerpc/64s/exception: Fix machine check no-loss idle wakeupNicholas Piggin
The architecture allows for machine check exceptions to cause idle wakeups which resume at the 0x200 address which has to return via the idle wakeup code, but the early machine check handler is run first. The case of a no state-loss sleep is broken because the early handler uses non-volatile register r1 , which is needed for the wakeup protocol, but it is not restored. Fix this by loading r1 from the MCE exception frame before returning to the idle wakeup code. Also update the comment which has become stale since the idle rewrite in C. This crash was found and fix confirmed with a machine check injection test in qemu powernv model (which is not upstream in qemu yet). Fixes: 10d91611f426d ("powerpc/64s: Reimplement book3s idle code in C") Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200508043408.886394-2-npiggin@gmail.com
2020-05-18powerpc/eeh: Release EEH device state synchronouslySam Bobroff
EEH device state is currently removed (by eeh_remove_device()) during the device release handler, which is invoked as the device's reference count drops to zero. This may take some time, or forever, as other threads may hold references. However, the PCI device state is released synchronously by pci_stop_and_remove_bus_device(). This mismatch causes problems, for example the device may be re-discovered as a new device before the release handler has been called, leaving the PCI and EEH state mismatched. So instead, call eeh_remove_device() from the bus device removal handlers, which are called synchronously in the removal path. Signed-off-by: Sam Bobroff <sbobroff@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/0a1f5105d3a33b1c090bba31de63eb0cdd25de7b.1588045502.git.sbobroff@linux.ibm.com
2020-05-18powerpc/eeh: Fix pseries_eeh_configure_bridge()Sam Bobroff
If a device is hot unplgged during EEH recovery, it's possible for the RTAS call to ibm,configure-pe in pseries_eeh_configure() to return parameter error (-3), however negative return values are not checked for and this leads to an infinite loop. Fix this by correctly bailing out on negative values. Signed-off-by: Sam Bobroff <sbobroff@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Nathan Lynch <nathanl@linux.ibm.com> Link: https://lore.kernel.org/r/1b0a6010a647dc915816e44845b64d72066676a7.1588045502.git.sbobroff@linux.ibm.com
2020-05-18powerpc/64: Update Speculation_Store_Bypass in /proc/<pid>/statusMichael Ellerman
Currently we don't report anything useful in /proc/<pid>/status: $ grep Speculation_Store_Bypass /proc/self/status Speculation_Store_Bypass: unknown Our mitigation is currently always a barrier instruction, which doesn't map that well onto the existing possibilities for the PR_SPEC values. However even if we added a "barrier" type PR_SPEC value, userspace would still need to consult some other source to work out which type of barrier to use. So reporting "vulnerable" seems sufficient, as userspace can see that and then consult its source to determine what barrier to use. Signed-off-by: Gustavo Walbon <gwalbon@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200402124929.3574166-1-mpe@ellerman.id.au
2020-05-15drivers/macintosh: Fix memleak in windfarm_pm112 driverMichael Ellerman
create_cpu_loop() calls smu_sat_get_sdb_partition() which does kmalloc() and returns the allocated buffer. In fact it's called twice, and neither buffer is freed. This results in a memory leak as reported by Erhard: unreferenced object 0xc00000047081f840 (size 32): comm "kwindfarm", pid 203, jiffies 4294880630 (age 5552.877s) hex dump (first 32 bytes): c8 06 02 7f ff 02 ff 01 fb bf 00 41 00 20 00 00 ...........A. .. 00 07 89 37 00 a0 00 00 00 00 00 00 00 00 00 00 ...7............ backtrace: [<0000000083f0a65c>] .smu_sat_get_sdb_partition+0xc4/0x2d0 [windfarm_smu_sat] [<000000003010fcb7>] .pm112_wf_notify+0x104c/0x13bc [windfarm_pm112] [<00000000b958b2dd>] .notifier_call_chain+0xa8/0x180 [<0000000070490868>] .blocking_notifier_call_chain+0x64/0x90 [<00000000131d8149>] .wf_thread_func+0x114/0x1a0 [<000000000d54838d>] .kthread+0x13c/0x190 [<00000000669b72bc>] .ret_from_kernel_thread+0x58/0x64 unreferenced object 0xc0000004737089f0 (size 16): comm "kwindfarm", pid 203, jiffies 4294880879 (age 5552.050s) hex dump (first 16 bytes): c4 04 01 7f 22 11 e0 e6 ff 55 7b 12 ec 11 00 00 ...."....U{..... backtrace: [<0000000083f0a65c>] .smu_sat_get_sdb_partition+0xc4/0x2d0 [windfarm_smu_sat] [<00000000b94ef7e1>] .pm112_wf_notify+0x1294/0x13bc [windfarm_pm112] [<00000000b958b2dd>] .notifier_call_chain+0xa8/0x180 [<0000000070490868>] .blocking_notifier_call_chain+0x64/0x90 [<00000000131d8149>] .wf_thread_func+0x114/0x1a0 [<000000000d54838d>] .kthread+0x13c/0x190 [<00000000669b72bc>] .ret_from_kernel_thread+0x58/0x64 Fix it by rearranging the logic so we deal with each buffer separately, which then makes it easy to free the buffer once we're done with it. Fixes: ac171c46667c ("[PATCH] powerpc: Thermal control for dual core G5s") Cc: stable@vger.kernel.org # v2.6.16+ Reported-by: Erhard F. <erhard_f@mailbox.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Tested-by: Erhard F. <erhard_f@mailbox.org> Link: https://lore.kernel.org/r/20200423060038.3308530-1-mpe@ellerman.id.au
2020-05-15selftests/powerpc: Add a test of counting larx/stcxMichael Ellerman
This is based on the count_instructions test. However this one also counts the number of failed stcx's, and in conjunction with knowing the size of the stcx loop, can calculate the total number of instructions executed even in the face of non-deterministic stcx failures. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200426114410.3917383-1-mpe@ellerman.id.au
2020-05-15powerpc: Drop unneeded cast in task_pt_regs()Michael Ellerman
There's no need to cast in task_pt_regs() as tsk->thread.regs should already be a struct pt_regs. If someone's using task_pt_regs() on something that's not a task but happens to have a thread.regs then we'll deal with them later. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200428123152.73566-1-mpe@ellerman.id.au
2020-05-15powerpc/64: Don't initialise init_task->thread.regsMichael Ellerman
Aneesh increased the size of struct pt_regs by 16 bytes and started seeing this WARN_ON: smp: Bringing up secondary CPUs ... ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at arch/powerpc/kernel/process.c:455 giveup_all+0xb4/0x110 Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-rc2-gcc-8.2.0-1.g8f6a41f-default+ #318 NIP: c00000000001a2b4 LR: c00000000001a29c CTR: c0000000031d0000 REGS: c0000000026d3980 TRAP: 0700 Not tainted (5.7.0-rc2-gcc-8.2.0-1.g8f6a41f-default+) MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 48048224 XER: 00000000 CFAR: c000000000019cc8 IRQMASK: 1 GPR00: c00000000001a264 c0000000026d3c20 c0000000026d7200 800000000280b033 GPR04: 0000000000000001 0000000000000000 0000000000000077 30206d7372203164 GPR08: 0000000000002000 0000000002002000 800000000280b033 3230303030303030 GPR12: 0000000000008800 c0000000031d0000 0000000000800050 0000000002000066 GPR16: 000000000309a1a0 000000000309a4b0 000000000309a2d8 000000000309a890 GPR20: 00000000030d0098 c00000000264da40 00000000fd620000 c0000000ff798080 GPR24: c00000000264edf0 c0000001007469f0 00000000fd620000 c0000000020e5e90 GPR28: c00000000264edf0 c00000000264d200 000000001db60000 c00000000264d200 NIP [c00000000001a2b4] giveup_all+0xb4/0x110 LR [c00000000001a29c] giveup_all+0x9c/0x110 Call Trace: [c0000000026d3c20] [c00000000001a264] giveup_all+0x64/0x110 (unreliable) [c0000000026d3c90] [c00000000001ae34] __switch_to+0x104/0x480 [c0000000026d3cf0] [c000000000e0b8a0] __schedule+0x320/0x970 [c0000000026d3dd0] [c000000000e0c518] schedule_idle+0x38/0x70 [c0000000026d3df0] [c00000000019c7c8] do_idle+0x248/0x3f0 [c0000000026d3e70] [c00000000019cbb8] cpu_startup_entry+0x38/0x40 [c0000000026d3ea0] [c000000000011bb0] rest_init+0xe0/0xf8 [c0000000026d3ed0] [c000000002004820] start_kernel+0x990/0x9e0 [c0000000026d3f90] [c00000000000c49c] start_here_common+0x1c/0x400 Which was unexpected. The warning is checking the thread.regs->msr value of the task we are switching from: usermsr = tsk->thread.regs->msr; ... WARN_ON((usermsr & MSR_VSX) && !((usermsr & MSR_FP) && (usermsr & MSR_VEC))); ie. if MSR_VSX is set then both of MSR_FP and MSR_VEC are also set. Dumping tsk->thread.regs->msr we see that it's: 0x1db60000 Which is not a normal looking MSR, in fact the only valid bit is MSR_VSX, all the other bits are reserved in the current definition of the MSR. We can see from the oops that it was swapper/0 that we were switching from when we hit the warning, ie. init_task. So its thread.regs points to the base (high addresses) in init_stack. Dumping the content of init_task->thread.regs, with the members of pt_regs annotated (the 16 bytes larger version), we see: 0000000000000000 c000000002780080 gpr[0] gpr[1] 0000000000000000 c000000002666008 gpr[2] gpr[3] c0000000026d3ed0 0000000000000078 gpr[4] gpr[5] c000000000011b68 c000000002780080 gpr[6] gpr[7] 0000000000000000 0000000000000000 gpr[8] gpr[9] c0000000026d3f90 0000800000002200 gpr[10] gpr[11] c000000002004820 c0000000026d7200 gpr[12] gpr[13] 000000001db60000 c0000000010aabe8 gpr[14] gpr[15] c0000000010aabe8 c0000000010aabe8 gpr[16] gpr[17] c00000000294d598 0000000000000000 gpr[18] gpr[19] 0000000000000000 0000000000001ff8 gpr[20] gpr[21] 0000000000000000 c00000000206d608 gpr[22] gpr[23] c00000000278e0cc 0000000000000000 gpr[24] gpr[25] 000000002fff0000 c000000000000000 gpr[26] gpr[27] 0000000002000000 0000000000000028 gpr[28] gpr[29] 000000001db60000 0000000004750000 gpr[30] gpr[31] 0000000002000000 000000001db60000 nip msr 0000000000000000 0000000000000000 orig_r3 ctr c00000000000c49c 0000000000000000 link xer 0000000000000000 0000000000000000 ccr softe 0000000000000000 0000000000000000 trap dar 0000000000000000 0000000000000000 dsisr result 0000000000000000 0000000000000000 ppr kuap 0000000000000000 0000000000000000 pad[2] pad[3] This looks suspiciously like stack frames, not a pt_regs. If we look closely we can see return addresses from the stack trace above, c000000002004820 (start_kernel) and c00000000000c49c (start_here_common). init_task->thread.regs is setup at build time in processor.h: #define INIT_THREAD { \ .ksp = INIT_SP, \ .regs = (struct pt_regs *)INIT_SP - 1, /* XXX bogus, I think */ \ The early boot code where we setup the initial stack is: LOAD_REG_ADDR(r3,init_thread_union) /* set up a stack pointer */ LOAD_REG_IMMEDIATE(r1,THREAD_SIZE) add r1,r3,r1 li r0,0 stdu r0,-STACK_FRAME_OVERHEAD(r1) Which creates a stack frame of size 112 bytes (STACK_FRAME_OVERHEAD). Which is far too small to contain a pt_regs. So the result is init_task->thread.regs is pointing at some stack frames on the init stack, not at a pt_regs. We have gotten away with this for so long because with pt_regs at its current size the MSR happens to point into the first frame, at a location that is not written to by the early asm. With the 16 byte expansion the MSR falls into the second frame, which is used by the compiler, and collides with a saved register that tends to be non-zero. As far as I can see this has been wrong since the original merge of 64-bit ppc support, back in 2002. Conceptually swapper should have no regs, it never entered from userspace, and in fact that's what we do on 32-bit. It's also presumably what the "bogus" comment is referring to. So I think the right fix is to just not-initialise regs at all. I'm slightly worried this will break some code that isn't prepared for a NULL regs, but we'll have to see. Remove the comment in head_64.S which refers to us setting up the regs (even though we never did), and is otherwise not really accurate any more. Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200428123130.73078-1-mpe@ellerman.id.au
2020-05-15powerpc/mm: Replace zero-length array with flexible-arrayGustavo A. R. Silva
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200507185755.GA15014@embeddedor
2020-05-15powerpc: Replace zero-length array with flexible-arrayGustavo A. R. Silva
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200507185749.GA14994@embeddedor
2020-05-15powerpc: Use trap metadata to prevent double restart rather than zeroing trapNicholas Piggin
It's not very nice to zero trap for this, because then system calls no longer have trap_is_syscall(regs) invariant, and we can't distinguish between sc and scv system calls (in a later patch). Take one last unused bit from the low bits of the pt_regs.trap word for this instead. There is not a really good reason why it should be in trap as opposed to another field, but trap has some concept of flags and it exists. Ideally I think we would move trap to 2-byte field and have 2 more bytes available independently. Add a selftests case for this, which can be seen to fail if trap_norestart() is changed to return false. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Make them static inlines] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200507121332.2233629-4-mpe@ellerman.id.au
2020-05-15powerpc: trap_is_syscall() helper to hide syscall trap numberNicholas Piggin
A new system call interrupt will be added with a new trap number. Hide the explicit 0xc00 test behind an accessor to reduce churn in callers. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Make it a static inline] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200507121332.2233629-3-mpe@ellerman.id.au
2020-05-15powerpc: Use set_trap() and avoid open-coding trap maskingNicholas Piggin
The pt_regs.trap field keeps 4 low bits for some metadata about the trap or how it was handled, which is masked off in order to test the architectural trap number. Add a set_trap() accessor to set this, equivalent to TRAP() for returning it. This is actually not quite the equivalent of TRAP() because it always clears the low bits, which may be harmless if it can only be updated via ptrace syscall, but it seems dangerous. In fact settting TRAP from ptrace doesn't seem like a great idea so maybe it's better deleted. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Make it a static inline rather than a shouty macro] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200507121332.2233629-2-mpe@ellerman.id.au
2020-05-15powerpc/64s: Always has full regs, so remove remnant checksNicholas Piggin
Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200507121332.2233629-1-mpe@ellerman.id.au
2020-05-11powerpc/kasan: Fix stack overflow by increasing THREAD_SHIFTChristophe Leroy
When CONFIG_KASAN is selected, the stack usage is increased. In the same way as x86 and arm64 architectures, increase THREAD_SHIFT when CONFIG_KASAN is selected. Fixes: 2edb16efc899 ("powerpc/32: Add KASAN support") Reported-by: <erhard_f@mailbox.org> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://bugzilla.kernel.org/show_bug.cgi?id=207129 Link: https://lore.kernel.org/r/2c50f3b1c9bbaa4217c9a98f3044bd2a36c46a4f.1586361277.git.christophe.leroy@c-s.fr
2020-05-11powerpc: Remove _ALIGN_UP(), _ALIGN_DOWN() and _ALIGN()Christophe Leroy
These three powerpc macros have been replaced by equivalent generic macros and are not used anymore. Remove them. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Joel Stanley <joel@jms.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/bb0a6081f7b95ee64ca20f92483e5b9661cbacb2.1587407777.git.christophe.leroy@c-s.fr
2020-05-11powerpc: Replace _ALIGN() by ALIGN()Christophe Leroy
_ALIGN() is specific to powerpc ALIGN() is generic and does the same Replace _ALIGN() by ALIGN() Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Joel Stanley <joel@jms.id.au> Link: https://lore.kernel.org/r/4006d9c8e69f8eaccee954899f6b5fb76240d00b.1587407777.git.christophe.leroy@c-s.fr
2020-05-11powerpc: Replace _ALIGN_UP() by ALIGN()Christophe Leroy
_ALIGN_UP() is specific to powerpc ALIGN() is generic and does the same Replace _ALIGN_UP() by ALIGN() Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Joel Stanley <joel@jms.id.au> Link: https://lore.kernel.org/r/8a6d7e45f7904c73a0af539642d3962e2a3c7268.1587407777.git.christophe.leroy@c-s.fr
2020-05-11powerpc: Replace _ALIGN_DOWN() by ALIGN_DOWN()Christophe Leroy
_ALIGN_DOWN() is specific to powerpc ALIGN_DOWN() is generic and does the same Replace _ALIGN_DOWN() by ALIGN_DOWN() Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Joel Stanley <joel@jms.id.au> Link: https://lore.kernel.org/r/3911a86d6b5bfa7ad88cd7c82416fbe6bb47e793.1587407777.git.christophe.leroy@c-s.fr
2020-05-11drivers/powerpc: Replace _ALIGN_UP() by ALIGN()Christophe Leroy
_ALIGN_UP() is specific to powerpc ALIGN() is generic and does the same Replace _ALIGN_UP() by ALIGN() Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Joel Stanley <joel@jms.id.au> Link: https://lore.kernel.org/r/a5945463f86c984151962a475a3ee56a2893e85d.1587407777.git.christophe.leroy@c-s.fr
2020-05-11powerpc/8xx: Update email address in MAINTAINERSChristophe Leroy
Since 01 May 2020, our email adresses have changed to @csgroup.eu Update MAINTAINERS accordingly. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/9fd0f9a827ebbeae64ad7a6f6c595d242f4dd5fc.1588747860.git.christophe.leroy@csgroup.eu
2020-05-11powerpc/5200: update contact emailWolfram Sang
My 'pengutronix' address is defunct for years. Merge the entries and use the proper contact address. Signed-off-by: Wolfram Sang <wsa@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200502142642.18979-1-wsa@kernel.org
2020-05-11powerpc: module_[32|64].c: replace swap function with built-in oneAndrey Abramov
Replace relaswap with built-in one, because relaswap does a simple byte to byte swap. Since Spectre mitigations have made indirect function calls more expensive, and the default simple byte copies swap is implemented without them, an "optimized" custom swap function is now a waste of time as well as code. Signed-off-by: Andrey Abramov <st5pub@yandex.ru> Reviewed-by: George Spelvin <lkml@sdf.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/994931554238042@iva8-b333b7f98ab0.qloud-c.yandex.net
2020-05-11powerpc/powernv: Fix a warning messageChristophe JAILLET
Fix a cut'n'paste error in a warning message. This should be 'cpu-idle-state-residency-ns' to match the property searched in the previous 'of_property_read_u32_array()' Fixes: 9c7b185ab2fe ("powernv/cpuidle: Parse dt idle properties into global structure") Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200502115949.139000-1-christophe.jaillet@wanadoo.fr
2020-05-06Merge the lockless page table walk rework into nextMichael Ellerman
This merges the lockless page table walk rework series from Aneesh. Because it touches powerpc KVM code we are sharing it with the kvm-ppc tree in our topic/ppc-kvm branch. This is the cover letter from Aneesh: Avoid IPI while updating page table entries. Problem Summary: Slow termination of KVM guest with large guest RAM config due to a large number of IPIs that were caused by clearing level 1 PTE entries (THP) entries. This is shown in the stack trace below. - qemu-system-ppc [kernel.vmlinux] [k] smp_call_function_many - smp_call_function_many - 36.09% smp_call_function_many serialize_against_pte_lookup radix__pmdp_huge_get_and_clear zap_huge_pmd unmap_page_range unmap_vmas unmap_region __do_munmap __vm_munmap sys_munmap system_call __munmap qemu_ram_munmap qemu_anon_ram_free reclaim_ramblock call_rcu_thread qemu_thread_start start_thread __clone Why we need to do IPI when clearing PMD entries: This was added as part of commit: 13bd817bb884 ("powerpc/thp: Serialize pmd clear against a linux page table walk") serialize_against_pte_lookup makes sure that all parallel lockless page table walk completes before we convert a PMD pte entry to regular pmd entry. We end up doing that conversion in the below scenarios 1) __split_huge_zero_page_pmd 2) do_huge_pmd_wp_page_fallback 3) MADV_DONTNEED running parallel to page faults. local_irq_disable and lockless page table walk: The lockless page table walk work with the assumption that we can dereference the page table contents without holding a lock. For this to work, we need to make sure we read the page table contents atomically and page table pages are not going to be freed/released while we are walking the table pages. We can achieve by using a rcu based freeing for page table pages or if the architecture implements broadcast tlbie, we can block the IPI as we walk the page table pages. To support both the above framework, lockless page table walk is done with irq disabled instead of rcu_read_lock() We do have two interface for lockless page table walk, gup fast and __find_linux_pte. This patch series makes __find_linux_pte table walk safe against the conversion of PMD PTE to regular PMD. gup fast: gup fast is already safe against THP split because kernel now differentiate between a pmd split and a compound page split. gup fast can run parallel to a pmd split and we prevent a parallel gup fast to a hugepage split, by freezing the page refcount and failing the speculative page ref increment. Similar to how gup is safe against parallel pmd split, this patch series updates the __find_linux_pte callers to be safe against a parallel pmd split. We do that by enforcing the following rules. 1) Don't reload the pte value, because that can be updated in parallel. 2) Code should be able to work with a stale PTE value and not the recent one. ie, the pte value that we are looking at may not be the latest value in the page table. 3) Before looking at pte value check for _PAGE_PTE bit. We now do this as part of pte_present() check. Performance: This speeds up Qemu guest RAM del/unplug time as below 128 core, 496GB guest: Without patch: munmap start: timer = 13162 ms, PID=7684 munmap finish: timer = 95312 ms, PID=7684 - delta = 82150 ms With patch (upto removing IPI) munmap start: timer = 196449 ms, PID=6681 munmap finish: timer = 196488 ms, PID=6681 - delta = 39ms With patch (with adding the tlb invalidate in pmdp_huge_get_and_clear_full) munmap start: timer = 196345 ms, PID=6879 munmap finish: timer = 196714 ms, PID=6879 - delta = 369ms Link: https://lore.kernel.org/r/20200505071729.54912-1-aneesh.kumar@linux.ibm.com
2020-05-05powerpc/mm/book3s64: Fix MADV_DONTNEED and parallel page fault raceAneesh Kumar K.V
MADV_DONTNEED holds mmap_sem in read mode and that implies a parallel page fault is possible and the kernel can end up with a level 1 PTE entry (THP entry) converted to a level 0 PTE entry without flushing the THP TLB entry. Most architectures including POWER have issues with kernel instantiating a level 0 PTE entry while holding level 1 TLB entries. The code sequence I am looking at is down_read(mmap_sem) down_read(mmap_sem) zap_pmd_range() zap_huge_pmd() pmd lock held pmd_cleared table details added to mmu_gather pmd_unlock() insert a level 0 PTE entry() tlb_finish_mmu(). Fix this by forcing a tlb flush before releasing pmd lock if this is not a fullmm invalidate. We can safely skip this invalidate for task exit case (fullmm invalidate) because in that case we are sure there can be no parallel fault handlers. This do change the Qemu guest RAM del/unplug time as below 128 core, 496GB guest: Without patch: munmap start: timer = 196449 ms, PID=6681 munmap finish: timer = 196488 ms, PID=6681 - delta = 39ms With patch: munmap start: timer = 196345 ms, PID=6879 munmap finish: timer = 196714 ms, PID=6879 - delta = 369ms Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200505071729.54912-23-aneesh.kumar@linux.ibm.com
2020-05-05powerpc/mm/book3s64: Avoid sending IPI on clearing PMDAneesh Kumar K.V
Now that all the lockless page table walk is careful w.r.t the PTE address returned, we can now revert commit: 13bd817bb884 ("powerpc/thp: Serialize pmd clear against a linux page table walk.") We also drop the equivalent IPI from other pte updates routines. We still keep IPI in hash pmdp collapse and that is to take care of parallel hash page table insert. The radix pmdp collapse flush can possibly be removed once I am sure generic code doesn't have the any expectations around parallel gup walk. This speeds up Qemu guest RAM del/unplug time as below 128 core, 496GB guest: Without patch: munmap start: timer = 13162 ms, PID=7684 munmap finish: timer = 95312 ms, PID=7684 - delta = 82150 ms With patch: munmap start: timer = 196449 ms, PID=6681 munmap finish: timer = 196488 ms, PID=6681 - delta = 39ms Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200505071729.54912-21-aneesh.kumar@linux.ibm.com
2020-05-05powerpc/kvm/book3s: Use pte_present instead of opencoding _PAGE_PRESENT checkAneesh Kumar K.V
This adds _PAGE_PTE check and makes sure we validate the pte value returned via find_kvm_host_pte. NOTE: this also considers _PAGE_INVALID to the software valid bit. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200505071729.54912-20-aneesh.kumar@linux.ibm.com
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