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Subject: Re: [PATCH 12/31] x86/entry/32: Add PTI cr3 switch to non-NMI
 entry/exit points
To:     Brian Gerst <brgerst@gmail.com>, Joerg Roedel <jroedel@suse.de>
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From:   Dave Hansen <dave.hansen@intel.com>
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Date:   Thu, 1 Mar 2018 10:36:21 -0800
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On 03/01/2018 10:24 AM, Brian Gerst wrote:
> 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.

It can happen with IF cleared.  I ran into it during PTI development
more than once.  That's why the debug fault code uses paranoid_entry on
64-bit just like the NMI code.