From: Razvan Cojocaru <rcojocaru@bitdefender.com>
To: Jan Beulich <JBeulich@suse.com>,
Alexandru Stefan ISAILA <aisaila@bitdefender.com>
Cc: PetreOvidiu PIRCALABU <ppircalabu@bitdefender.com>,
"tamas@tklengyel.com" <tamas@tklengyel.com>,
"wl@xen.org" <wl@xen.org>,
"george.dunlap@eu.citrix.com" <george.dunlap@eu.citrix.com>,
"andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>,
"paul.durrant@citrix.com" <paul.durrant@citrix.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
"roger.pau@citrix.com" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH v7] x86/emulate: Send vm_event from emulate
Date: Fri, 19 Jul 2019 16:30:43 +0300 [thread overview]
Message-ID: <8817949d-a99c-ae0f-93b1-13c0bebacae6@bitdefender.com> (raw)
In-Reply-To: <e61a882e-d2ea-a03d-fde8-2c2befd865da@suse.com>
On 7/19/19 4:18 PM, Jan Beulich wrote:
> On 19.07.2019 14:34, Alexandru Stefan ISAILA wrote:
>> On 18.07.2019 15:58, Jan Beulich wrote:
>>> On 03.07.2019 12:56, Alexandru Stefan ISAILA wrote:
>>>> A/D bit writes (on page walks) can be considered benign by an introspection
>>>> agent, so receiving vm_events for them is a pessimization. We try here to
>>>> optimize by fitering these events out.
>>>
>>> But you add the sending of more events - how does "filter out" match
>>> the actual implementation?
>>
>> The events are send only if there is a mem access violation therefore we
>> are filtering and only sending the events that are interesting to
>> introspection.
>
> Where is it that you prevent any event from being sent? As said,
> reading the patch I only see new sending sites to get added.
If we don't emulate, we would receive the page-walk-generated events
_and_ the touching-the-page-the-instruction-is-touching events.
In comparison to the "hardware" case, the case where we emulate the
instruction with the page walk ignoring the EPT results in less events,
hence the prevention of some events being sent out.
Thanks,
Razvan
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next prev parent reply other threads:[~2019-07-19 13:31 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-03 10:56 [Xen-devel] [PATCH v7] x86/emulate: Send vm_event from emulate Alexandru Stefan ISAILA
2019-07-11 17:13 ` Tamas K Lengyel
2019-07-12 1:28 ` Jan Beulich
2019-07-15 8:52 ` Alexandru Stefan ISAILA
2019-07-18 12:58 ` Jan Beulich
2019-07-19 12:34 ` Alexandru Stefan ISAILA
2019-07-19 13:18 ` Jan Beulich
2019-07-19 13:30 ` Razvan Cojocaru [this message]
2019-07-19 13:38 ` Jan Beulich
2019-07-19 14:23 ` Razvan Cojocaru
2019-07-29 8:12 ` Alexandru Stefan ISAILA
2019-07-29 11:30 ` Jan Beulich
2019-07-22 7:51 ` Alexandru Stefan ISAILA
2019-07-30 12:21 ` Alexandru Stefan ISAILA
2019-07-30 13:27 ` Jan Beulich
2019-07-30 14:12 ` Alexandru Stefan ISAILA
2019-07-30 14:54 ` Jan Beulich
2019-07-30 15:28 ` Alexandru Stefan ISAILA
2019-08-20 20:11 ` Andrew Cooper
2019-08-27 8:26 ` Jan Beulich
2019-09-02 14:36 ` Alexandru Stefan ISAILA
2019-09-02 14:59 ` Jan Beulich
2019-07-23 8:17 ` Alexandru Stefan ISAILA
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