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: Thu, 30 May 2019 08:59:13 +0000	[thread overview]
Message-ID: <b6f3254b-2bce-ecd6-cddb-10131f075fb6@bitdefender.com> (raw)
In-Reply-To: <5CE51CBD0200007800231438@prv1-mh.provo.novell.com>

> 
>> +        return false;
>> +
>> +    rc = hvmemul_linear_to_phys(gla, &gpa, bytes, &reps, pfec, &ctxt);
> 
> As said before - I don't think it's a good idea to do the page walk
> twice: This and the pre-existing one can easily return different
> results.

What preexisting page walk are you talking about here? I don't think 
there is a way to get the gpa by passing it from somewhere.

Alex

> 
> Additionally, as also said before (I think), the function may raise
> #PF, which you don't seem to deal with despite discarding the
> X86EMUL_EXCEPTION return value ...
> 
>> +    if ( rc != X86EMUL_OKAY )
>> +        return false;
> 
> ... here.
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