On Wed, Jan 10, 2018 at 10:34:18AM +0000, Peter Maydell wrote: > On 10 January 2018 at 08:57, Steven Seeger > <steven.see...@flightsystems.net> wrote: > > Sorry for another post. I did a bisect and found what is the bad commit for > > me: > > > > 044897ef4a22af89aecb8df509477beba0a2e0ce is the first bad commit > > commit 044897ef4a22af89aecb8df509477beba0a2e0ce > > Author: Richard Purdie <richard.pur...@linuxfoundation.org> > > Date: Mon Dec 4 22:25:43 2017 +0000 > > > > target/ppc: Fix system lockups caused by interrupt_request state > > corruption > > Great -- thanks for the bisect. Let's take this to the -devel list; > I've cc'd the PPC maintainers. > > Context: Steven reports that we broke -icount for PPC guests with > this commit: > > $ ./build/all/ppc-softmmu/qemu-system-ppc -icount auto > qemu: fatal: Raised interrupt while not in I/O function > NIP fff08978 LR fff08904 CTR 00000000 XER 00000000 CPU#0 > MSR 00000000 HID0 00000000 HF 00000000 iidx 3 didx 3 > Bad icount read > > The backtrace from the assert is: > > #0 tcg_handle_interrupt (cpu=0x7ffff7fc2010, mask=4) at qemu/accel/tcg/tcg- > all.c:58 > #1 0x0000555555962aa4 in cpu_interrupt (cpu=0x7ffff7fc2010, mask=4) at qemu/ > include/qom/cpu.h:859 > #2 0x0000555555962e55 in cpu_interrupt_exittb (cs=0x7ffff7fc2010) at qemu/ > target/ppc/helper_regs.h:105 > #3 0x0000555555964505 in do_rfi (env=0x7ffff7fca2b0, nip=197460, msr=4096) > at qemu/target/ppc/excp_helper.c:998 > #4 0x0000555555964555 in helper_rfi (env=0x7ffff7fca2b0) at qemu/target/ppc/ > excp_helper.c:1008 > #5 0x00007fffe7c124b9 in code_gen_buffer () > > The problem is that icount was relying on the previous > handling of do_rfi() as "just set state as we know we're > going to be last insn in the TB". > > Not sure how best to fix this (mark the insn as IO ok?)
Aw, man. I've become target-ppc tcg maintainer by default, but tbh my
knowledge wasn't really deep enough to understand the problem that
044897ef was fixing in the first place. And I barely know what icount
does at all.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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