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

[Gleb Natapov <gleb@redhat.com>]

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.

> - 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.