From: Alexandru Stefan ISAILA <aisaila@bitdefender.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Petre Ovidiu PIRCALABU <ppircalabu@bitdefender.com>,
"tamas@tklengyel.com" <tamas@tklengyel.com>,
"wl@xen.org" <wl@xen.org>,
"rcojocaru@bitdefender.com" <rcojocaru@bitdefender.com>,
"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: Tue, 30 Jul 2019 12:21:49 +0000 [thread overview]
Message-ID: <1bdaee7b-a01f-7be8-426f-fe6c678c2859@bitdefender.com> (raw)
In-Reply-To: <23cebb01-38fc-ba49-5a71-e6129152e488@bitdefender.com>
>>>>> @@ -629,6 +697,14 @@ static void *hvmemul_map_linear_addr(
>>>>>
>>>>> ASSERT(p2mt == p2m_ram_logdirty || !p2m_is_readonly(p2mt));
>>>>> }
>>>>> +
>>>>> + if ( curr->arch.vm_event &&
>>>>> + curr->arch.vm_event->send_event &&
>>>>> + hvm_emulate_send_vm_event(addr, gfn, pfec) )
>>>>> + {
>>>>> + err = ERR_PTR(~X86EMUL_RETRY);
>>>>> + goto out;
>>>>> + }
>>>>
>>>> Did you notice that there's an immediate exit from the loop only
>>>> in case the linear -> physical translation fails? This is
>>>> relevant for page fault delivery correctness for accesses
>>>> crossing page boundaries. I think you want to use
>>>> update_map_err() and drop the "goto out". I can't really make up
>>>
>>> By update_map_err() are you saying to have the err var assigned and then
>>> drop "goto out"? If so how do I keep the err from my access violation
>>> without exiting from the loop?
>>
>> Counter question: Why do you _need_ to keep "your" value of err?
>> If, just as an example, there's going to be a #PF on the other
>> half of the access, then "your" access violation is of no interest
>> at all.
>
> You are right, there is no need to keep the "goto out" here. It was just
> for optimization in the idea that there is no need to do further steps
> but I can drop the "goto out" and the code will work the same.
>
There is a problem with dropping the "goto out". If everything goes fine
then it will return the mapping and I don't want that. This can be
stopped by checking if ( err ) after the loop and it is not null then
goto out. And going with this idea I can init *err = NULL and drop the
err = NULL from hvmemul_map_linear_addr(). Is this ok for the next version?
Regards,
Alex
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next prev parent reply other threads:[~2019-07-30 12:22 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
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 [this message]
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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