Re: [PATCH] KVM: VMX: Update instruction length on intercepted BP

Gleb Natapov
2010-02-16T11:26:00Z

On Tue, Feb 16, 2010 at 01:20:21PM +0200, Gleb Natapov wrote:
> On Sun, Feb 14, 2010 at 06:49:23PM +0100, Jan Kiszka wrote:
> > > Lets check if SVM works. I can do that if you tell me how.
> >
> > - Fire up some Linux guest with gdb installed
> > - Attach gdb to gdbstub of the VM
> I get "Remote 'g' packet reply is too long". My guest and host are 64
> bit.
>
May fault. Provided wrong file to gdb.

> > - Set a soft breakpoint in guest kernel, ideally where it does not
> > immediately trigger, e.g. on sys_reboot (use grep sys_reboot
> > /proc/kallsyms if you don't have symbols for the guest kernel)
> > - Start gdb /bin/true in the guest
> > - run
> >
> > As gdb sets some automatic breakpoints, this already exercises the
> > reinjection of #BP.
> >
> > > My concern is
> > > that if SVM doesn't work we will write another way to handle this
> > > situation that will work on SVM and VMX and then we will have code in
> > > VMX that is not needed, but we have to support it.
> >
> > I understand your concerns, but I do not share them ATM. I bet we will
> > need some workaround for older SVM, but it will be some SVM-only thing.
> > Anyway, we can wait with this patch a few days until we know more.
> >
> > Jan
> >
>
>
>
> --
> Gleb.
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--
Gleb.