* Re: [Qemu-devel] [Qemu-discuss] ppc and icount
2018-01-10 10:34 ` [Qemu-devel] [Qemu-discuss] ppc and icount Peter Maydell
@ 2018-01-11 2:44 ` David Gibson
2018-01-12 14:55 ` [Qemu-devel] [Qemu-ppc] " Laurent Vivier
1 sibling, 0 replies; 3+ messages in thread
From: David Gibson @ 2018-01-11 2:44 UTC (permalink / raw)
To: Peter Maydell
Cc: steven.seeger, qemu-discuss, QEMU Developers, qemu-ppc,
Alexander Graf, Richard Purdie, Richard Henderson
[-- Attachment #1: Type: text/plain, Size: 2307 bytes --]
On Wed, Jan 10, 2018 at 10:34:18AM +0000, Peter Maydell wrote:
> On 10 January 2018 at 08:57, Steven Seeger
> <steven.seeger@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.purdie@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
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [Qemu-ppc] [Qemu-discuss] ppc and icount
2018-01-10 10:34 ` [Qemu-devel] [Qemu-discuss] ppc and icount Peter Maydell
2018-01-11 2:44 ` David Gibson
@ 2018-01-12 14:55 ` Laurent Vivier
1 sibling, 0 replies; 3+ messages in thread
From: Laurent Vivier @ 2018-01-12 14:55 UTC (permalink / raw)
To: Peter Maydell, steven.seeger
Cc: Richard Henderson, QEMU Developers, Richard Purdie, qemu-ppc,
qemu-discuss, David Gibson
On 10/01/2018 11:34, Peter Maydell wrote:
> On 10 January 2018 at 08:57, Steven Seeger
> <steven.seeger@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.purdie@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?)
According to what I see for other targets I think we should add a
POWERPC_EXCP_RFI and call do_rfi() and friends from powerpc_excp().
Thanks,
Laurent
^ permalink raw reply [flat|nested] 3+ messages in thread