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Re: [PATCH 1/2] x86/time: use fake read_tsc()


  • To: Jan Beulich <jbeulich@xxxxxxxx>
  • From: Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>
  • Date: Tue, 1 Mar 2022 14:39:05 +0000
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  • Thread-topic: [PATCH 1/2] x86/time: use fake read_tsc()

On 01/03/2022 14:14, Jan Beulich wrote:
> On 01.03.2022 14:07, Andrew Cooper wrote:
>> On 01/03/2022 11:05, Jan Beulich wrote:
>> That said... what's wrong a plain NULL?  I can't see any need for a
>> magic constant here.
> Are you fancying an XSA for a call through NULL in PV guest context?

Why do you think that a risk?  Only non-NULL function pointers are
followed, and altcall resolves safely if the pointer is still NULL.

And on that subject, don't we not hit the altcall's BUG_ON() for
exceeding disp32?

~Andrew

 


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