Re: [PATCH 12/31] x86/entry/32: Add PTI cr3 switch to non-NMI entry/exit points

[Joerg Roedel]

On Thu, Mar 01, 2018 at 09:33:11AM -0500, Waiman Long wrote:
> On 03/01/2018 08:34 AM, Joerg Roedel wrote:
> I think that should fix the issue of debug exception from userspace.
> 
> One thing that I am not certain about is whether debug exception can
> happen even if the IF flag is cleared. If it can, debug exception should
> be handled like NMI as the state of the CR3 can be indeterminate if the
> exception happens in the entry/exit code.

I am actually not 100% sure where it can happen, from the code it can
happen from anywhere, except when we are running on an espfix stack.

So I am not sure we need the same complex handling NMIs need wrt. to
switching the cr3s.


	Joerg