[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH for-4.7] x86/pv: Correctly fold vIOPL back into vcpu_guest_context

On Mon, Apr 11, 2016 at 10:08:58AM -0400, Boris Ostrovsky wrote:
> On 04/11/2016 05:03 AM, Andrew Cooper wrote:
> >c/s f71ecb6 "x86: introduce a new VMASSIST for architectural behaviour of
> >iopl" shifted the vcpu iopl field by 12, but didn't update the logic which
> >reconstructs the guests eflags for migration.
> >
> >Existing guest kernels set a vIOPL of 1, to prevent them from faulting when
> >accessing IO ports.  This bug manifests as a crash after migrate, as the 
> >vIOPL
> >reverts back to the default of 0, and the guest suffers an unexpected #GP
> >fault.
> >
> >Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Tested-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> (save/restore was part of brokenness as well, obviously)


Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.