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 14:12:13 +0000 [thread overview]
Message-ID: <c7060d91-851a-ba04-56c3-90f1aed65913@bitdefender.com> (raw)
In-Reply-To: <60651ad5-f0bd-caad-77f6-5f8fb71a8319@suse.com>
On 30.07.2019 16:27, Jan Beulich wrote:
> On 30.07.2019 14:21, Alexandru Stefan ISAILA wrote:
>>
>>>>>>> @@ -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?
>
> I'd prefer to see the code to decide. If you want this settled before
> sending the next full version, then please send at least the resulting
> patch hunk(s).
>
Here is a diff for hvmemul_map_linear_addr():
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index d75d3e6fd6..49dbfa730c 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -543,10 +543,11 @@ static void *hvmemul_map_linear_addr(
struct hvm_emulate_ctxt *hvmemul_ctxt)
{
struct vcpu *curr = current;
- void *err, *mapping;
+ void *err = NULL, *mapping;
unsigned int nr_frames = ((linear + bytes - !!bytes) >> PAGE_SHIFT) -
(linear >> PAGE_SHIFT) + 1;
unsigned int i;
+ gfn_t gfn;
/*
* mfn points to the next free slot. All used slots have a page
reference
@@ -585,7 +586,7 @@ static void *hvmemul_map_linear_addr(
ASSERT(mfn_x(*mfn) == 0);
res = hvm_translate_get_page(curr, addr, true, pfec,
- &pfinfo, &page, NULL, &p2mt);
+ &pfinfo, &page, gfn, &p2mt);
switch ( res )
{
@@ -599,7 +600,6 @@ static void *hvmemul_map_linear_addr(
goto out;
case HVMTRANS_bad_gfn_to_mfn:
- err = NULL;
goto out;
case HVMTRANS_gfn_paged_out:
@@ -622,14 +622,22 @@ static void *hvmemul_map_linear_addr(
}
if ( p2mt == p2m_ioreq_server )
- {
- err = NULL;
goto out;
- }
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);
}
}
+ /* Check if any vm_event was sent */
+ if ( err )
+ goto out;
/* Entire access within a single frame? */
if ( nr_frames == 1 )
Alex
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next prev parent reply other threads:[~2019-07-30 14:12 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
2019-07-30 13:27 ` Jan Beulich
2019-07-30 14:12 ` Alexandru Stefan ISAILA [this message]
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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