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[Qemu-ppc] [PATCH for-4.0 0/3] target/ppc: Fix pseries.cap-ibs=workaroun
From: |
Greg Kurz |
Subject: |
[Qemu-ppc] [PATCH for-4.0 0/3] target/ppc: Fix pseries.cap-ibs=workaround with TCG |
Date: |
Fri, 22 Mar 2019 19:03:35 +0100 |
User-agent: |
StGit/unknown-version |
Since recent commit 2782ad4c4102 "target/ppc/spapr: Enable mitigations by
default for pseries-4.0 machine type", some recent distros, eg. fedora29,
fail to boot under TCG because of a kernel panic:
[ 0.614425] Oops: Exception in kernel mode, sig: 4 [#1]
[ 0.618832] LE SMP NR_CPUS=1024 NUMA pSeries
[ 0.621868] Modules linked in:
[ 0.624958] CPU: 0 PID: 0 Comm: swapper/0 Not tainted
4.20.16-200.fc29.ppc64le #1
[ 0.625978] NIP: c00000000000bf00 LR: c00000000000e268 CTR: 0000000000007fff
[ 0.626572] REGS: c0000000015a3750 TRAP: 0700 Not tainted
(4.20.16-200.fc29.ppc64le)
[ 0.626835] MSR: 8000000002089033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR: 44828222
XER: 00000000
[ 0.628497] CFAR: c00000000000bee4 IRQMASK: 1
[ 0.628497] GPR00: c00000000001fbc8 c0000000015a39e0 c0000000015a6200
c000000001533450
[ 0.628497] GPR04: c00000003e5819d0 c00000003ff15f68 0000000000000000
0000000022f63728
[ 0.628497] GPR08: 0000000000000000 0000000000007fff 0000000000000000
0000000000000000
[ 0.628497] GPR12: 0000000000008000 c0000000018b0000 000000003dc5fd20
0000000002e75e90
[ 0.628497] GPR16: 0000000002e75d40 c00000003e594d00 000000003dc5fd20
0000000002e90b50
[ 0.628497] GPR20: 000000003e45e800 c000000001531a80 c000000001532100
0000000044828222
[ 0.628497] GPR24: c000000001533450 c000000001533450 c00000003e5819d0
c0000000010e51e0
[ 0.628497] GPR28: c0000000015d5c18 c000000001531a80 c00000003e580000
c000000001531a80
[ 0.631710] NIP [c00000000000bf00] flush_count_cache+0x120/0x2420
[ 0.631905] LR [c00000000000e268] _switch+0x68/0x180
[ 0.632585] Call Trace:
[ 0.633490] [c0000000015a39e0] [c0000000015dbd58] __cpu_online_mask+0x0/0x80
(unreliable)
[ 0.634383] [c0000000015a3bc0] [c00000000001fbc8] __switch_to+0x348/0x500
[ 0.634614] [c0000000015a3c20] [c000000000c509dc] __schedule+0x2bc/0xac0
[ 0.634731] [c0000000015a3cf0] [c000000000c51648]
preempt_schedule_common+0x38/0x60
[ 0.634852] [c0000000015a3d10] [c000000000c516d4] _cond_resched+0x64/0x80
[ 0.635527] [c0000000015a3d40] [c00000000011a190]
copy_process.isra.4.part.5+0xc90/0x1d20
[ 0.635656] [c0000000015a3e40] [c00000000011b414] _do_fork+0xd4/0x470
[ 0.635772] [c0000000015a3eb0] [c00000000011b88c] kernel_thread+0x3c/0x50
[ 0.635891] [c0000000015a3ed0] [c000000000010b08] rest_init+0x98/0xf8
[ 0.636025] [c0000000015a3f00] [c000000000fe4084] start_kernel+0x658/0x67c
[ 0.636163] [c0000000015a3f90] [c00000000000b37c]
start_here_common+0x1c/0x520
[ 0.636763] Instruction dump:
[ 0.640925] 48000005 48000005 48000005 48000005 48000005 4800001c 60000000
60000000
[ 0.641448] 60000000 60000000 60000000 60000000 <7d2803a6> 39207fff 7d2903a6
4c400420
[ 0.648580] ---[ end trace 1dcd9494acdef8df ]---
[ 0.649361]
[ 1.657870] Kernel panic - not syncing: Attempted to kill the idle task!
The following error is also printed by QEMU:
Opcode 13 10 10 00 (4c400420) leaked temporaries
The root cause behind the panic is that the linux kernel uses for spectre v2
mitigation a form of the bcctr instruction that we don't support. This gets
triggered when passing cap-ibs=workaround machine option, which is the default
since 2782ad4c4102.
The TCG temp leak comes from some missing tcg_temp_free()s on the
exception path.
This series fixes the leak and adds support for the invalid form of bcctr.
Since this adds yet another user of PPC_SEGMENT_64B to discriminate CPU
models that should expose the _new_ behaviour, the final patch introduces
a helper for that purpose.
--
Greg
---
Greg Kurz (3):
target/ppc: Fix TCG temporary leaks in gen_bcond()
target/ppc: Enable "decrement and test CTR" version of bcctr
target/ppc: Consolidate 64-bit server processor detection in a helper
hw/ppc/ppc.c | 2 +-
target/ppc/cpu.h | 6 +++++
target/ppc/helper_regs.h | 2 +-
target/ppc/translate.c | 58 ++++++++++++++++++++++++++++++++--------------
4 files changed, 48 insertions(+), 20 deletions(-)