Re: [PATCH v4 2/2] x86/emulate: Send vm_event from emulate

From: Alexandru Stefan ISAILA <aisaila@bitdefender.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Tamas K Lengyel <tamas@tklengyel.com>,
	Wei Liu <wei.liu2@citrix.com>,
	Razvan Cojocaru <rcojocaru@bitdefender.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Paul Durrant <paul.durrant@citrix.com>,
	xen-devel <xen-devel@lists.xenproject.org>,
	Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: [PATCH v4 2/2] x86/emulate: Send vm_event from emulate
Date: Wed, 22 May 2019 13:50:33 +0000	[thread overview]
Message-ID: <b2619cfc-1ee1-c495-40e2-2652b24ad78c@bitdefender.com> (raw)
In-Reply-To: <5CE54FD30200007800231603@prv1-mh.provo.novell.com>

>>> Despite what was said before you're still doing things a 2nd time
>>> here just because of hvmemul_send_vm_event()'s needs, even
>>> if that function ends up bailing right away.
>>
>> I don't understand what things are done 2 times. Can you please explain?
> 
> You add code above that exists already in __hvmemul_read().
> Even worse, __hvmemul_read() may not need calling at all, in
> which case there's no (emulated) memory access and hence
> imo there shouldn't be any event. Plus, just like in the
> hvmemul_linear_to_phys() case there may be an exception
> raised by the function, yet just like there you also discard the
> return value saying so without also zapping the exception.
> 

Isn't it safer to move the hvmemul_send_vm_event() form 
hvmemul_insn_fetch() to __hvmemul_read()?

Alex
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