Re: [Qemu-devel] [PATCH] Fix a bug in mtsr/mtsrin emulation on ppc64

[Alexander Graf]

On 21.05.2011, at 03:58, Alexander Graf wrote:

> 
> Am 21.05.2011 um 00:37 schrieb Andreas Färber <address@hidden>:
> 
>> Am 20.05.2011 um 09:40 schrieb Alexander Graf:
>> 
>>> On 20.05.2011, at 05:34, David Gibson wrote:
>>> 
>>>> Early ppc64 CPUs include a hack to partially simulate the ppc32 segment
>>>> registers, by translating writes to them into writes to the SLB.  This is
>>>> not used by any current Linux kernel, but it is used by the openbios used
>>>> in the qemu mac99 model.
>>>> 
>>>> Commit 81762d6dd0d430d87024f2c83e9c4dcc4329fb7d, cleaning up the SLB
>>>> handling introduced a bug in this code, breaking the openbios currently in
>>>> qemu.  Specifically, there was an off by one error bitshuffling the
>>>> register format used by mtsr into the format needed for the SLB load,
>>>> causing the flag bits to end up in the wrong place.  This caused the
>>>> storage keys to be wrong under openbios, meaning that the translation code
>>>> incorrectly thought a legitimate access was a permission violation.
>>>> 
>>>> This patch fixes the bug, at the same time it fixes some build bug in the
>>>> MMU debugging code (only exposed when DEBUG_MMU is enabled).
>>> 
>>> Thanks, applied to ppc-next :)
>> 
>> Nack, this does not fix ppc64 for me! How did you test it, Alex???
> 
> I booted a ppc64 kernel on a ppc64 Linux system with tcg and it booted fine 
> for me. Maybe you're hitting yet another issue?

Sorry for not being overly precise; host userland was running in 32-bit.


Alex