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From: Peter Maydell <peter.maydell@linaro.org>
Date: Thu, 21 Feb 2019 14:23:06 +0000
Message-ID: <CAFEAcA8FAja8DzrmmARZ3eZHgj1BrkNyak9HWffL7QLP27o45g@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Subject: Re: [Qemu-devel] [PULL 11/27] arm: Allow system registers for KVM
 guests to be changed by QEMU code
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To: Auger Eric <eric.auger@redhat.com>
Cc: QEMU Developers <qemu-devel@nongnu.org>, =?UTF-8?B?QWxleCBCZW5uw6ll?= <alex.bennee@linaro.org>

On Thu, 21 Feb 2019 at 14:20, Auger Eric <eric.auger@redhat.com> wrote:
> On 2/14/19 8:05 PM, Peter Maydell wrote:
> > Support this by making kvm_arch_put_registers() synchronize
> > CPU state back into the list. We sync only those registers
> > where the initial write succeeds, which should be sufficient.

> This commit introduces a regression when running with EDK2 FW:
>
> I get the following traces:
>
> error: kvm run failed Function not implemented
>  PC=000000013f5a6208 X00=00000000404003c4 X01=000000000000003a
> X02=0000000000000000 X03=00000000404003c4 X04=0000000000000000
> X05=0000000096000046 X06=000000013d2ef270 X07=000000013e3d1710
> X08=09010755ffaf8ba8 X09=ffaf8b9cfeeb5468 X10=feeb546409010756
> X11=09010757ffaf8b90 X12=feeb50680903068b X13=090306a1ffaf8bc0
> X14=0000000000000000 X15=0000000000000000 X16=000000013f872da0
> X17=00000000ffffa6ab X18=0000000000000000 X19=000000013f5a92d0
> X20=000000013f5a7a78 X21=000000000000003a X22=000000013f5a7ab2
> X23=000000013f5a92e8 X24=000000013f631090 X25=0000000000000010
> X26=0000000000000100 X27=000000013f89501b X28=000000013e3d14e0
> X29=000000013e3d12a0 X30=000000013f5a2518  SP=000000013b7be0b0
> PSTATE=404003c4 -Z-- EL1t
>
>
> and in host dmesg:
> [ 3507.926571] kvm [35042]: load/store instruction decoding not implemented

Ugh. Presumably this means that at some point we're writing
back a wrong value to a guest system register and making
it fall over :-( I guess debug would be by identifying
when execution diverges...

thanks
-- PMM