Re: [PATCH v5 untested] kvm: better MWAIT emulation for guests

Michael S. Tsirkin
2017-03-16T19:27:56Z

On Thu, Mar 16, 2017 at 03:24:41PM -0400, Gabriel L. Somlo wrote:
> On Thu, Mar 16, 2017 at 08:29:32PM +0200, Michael S. Tsirkin wrote:
> > Let's take a step back and try to figure out how is
> > mwait called. How about dumping code of VCPUs
> > around mwait? gdb disa command will do this.
>
> Started guest with '-s', tried to attach from gdb with
> "target remote localhost:1234", got
> "remote 'g' packet reply is too long: <lengthy string of numbers>"

Try

set arch x86-64:x86-64

> Tried typing 'cont' in the qemu monitor, got os x to crash:
>
> panic (cpu 1 caller 0xffffff7f813ff488): pmLock: waited too long, held
> by 0xffffff7f813eff65
>
> Hmm, maybe that's where it keeps its monitor/mwait idle loop.
> Restarted the guest, tried this from monitor:
>
> dump-guest-memory foobar 0xffffff7f813e0000 0x20000
>
> Got "'dump-guest-memory' has failed: integer is for 32-bit values"
>
> Hmmm... I have no idea what I'm doing anymore at this point... :)
>
> --G

I think 0xffffff7f813ff488 is a PC.

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MST