Re: [PATCH] KVM: unbreak userspace that does not sets tss address

[Gleb Natapov <gleb@redhat.com>]

On Mon, Mar 07, 2011 at 05:23:02PM +0100, Jan Kiszka wrote:
> On 2011-03-07 17:20, Gleb Natapov wrote:
> > On Mon, Mar 07, 2011 at 04:49:28PM +0100, Jan Kiszka wrote:
> >> On 2011-03-07 16:19, Gleb Natapov wrote:
> >>> Commit 6440e5967bc broke old userspaces that do not set tss address
> >>> before entering vcpu. Unbreak it by setting tss address to a safe
> >>> value on the first vcpu entry. New userspaces should set tss address,
> >>> so print warning in case it doesn't.
> >>
> >> Wouldn't allow runtime warnings but wouldn't it be cleaner otherwise to
> >> start vcpus with a default tss address like that, ie. add the logic to
> >> vmx_create_vcpu?
> >>
> > Userspace can create VCPU before setting tss address. We will have to
> > have logic that removes default tss slot in set_tss_address callback.
> > Also this default slot may prevent userspace from creating another slot
> > at this physical address which is perfectly legitimate thing for userspace
> > to do.
> 
> Ah, ok. I thought you could simple override the tss slot by calling the
> corresponding service again.
> 
I think you need to delete it first, but even if not the second problem
remains.

--
			Gleb.