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From: Julien Grall <julien.grall@arm.com>
To: Tamas K Lengyel <tamas@tklengyel.com>
Cc: "Edgar E. Iglesias" <edgar.iglesias@gmail.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Xen-devel <xen-devel@lists.xenproject.org>,
	Steve Capper <Steve.Capper@arm.com>
Subject: Re: [PATCH v5 5/9] monitor: ARM SMC events
Date: Mon, 6 Jun 2016 16:54:45 +0100	[thread overview]
Message-ID: <57559CC5.7070805@arm.com> (raw)
In-Reply-To: <CABfawh=y=7zxcJ2UxUq=OqqVmhwSCn9dLR2nu-PagWv5huq8BA@mail.gmail.com>

Hello Tamas,

On 06/06/16 16:24, Tamas K Lengyel wrote:
>
> On Jun 6, 2016 04:08, "Julien Grall" <julien.grall@arm.com
> <mailto:julien.grall@arm.com>> wrote:
>  >
>  > Hello,
>  >
>  >
>  > On 04/06/2016 18:40, Tamas K Lengyel wrote:
>  >>
>  >> On Sat, Jun 4, 2016 at 3:03 AM, Edgar E. Iglesias
>  >> <edgar.iglesias@gmail.com <mailto:edgar.iglesias@gmail.com>> wrote:
>  >>>
>  >>> Forwarding SMC events for SMC insns that didn't pass the condition
> tests
>  >>> doesn't make any sense to me. It'll just make the receivers job harder.
>  >>> Why would a receiver want to do anything else than drop these?
>  >>> If it actually does look at them it'll be looking at implementation
>  >>> defined HW behaviour that may vary between CPU implementations.
>  >>
>  >>
>  >> If for no other purposes it may be useful to log them to be able to
>  >> study the CPU implementation's behavior.
>  >
>  >
>  > I cannot see how you will be able to study ARM CPU implementation's
> behavior with VM event. Though I am not familiar with it.
>  >
>  > For now, it looks like to me that forwarding conditional SMC even if
> the condition check has failed will require a lot of code in each
> introspection applications, not to mention that they will need specific
> code to distinguish ARMv7 vs ARMv8.
>
> Why would it require any more code? Right now the only thing the
> listener can do is to increment pc to jump over the SMC. That would be
> the same regardless of what type it was. As for checking whether it was
> v7 or v8, if that is of interest to the app it should implement the
> appropriate logic for it. I don't see a problem there either.

A listener can to do more then incrementing pc to jump over the SMC. The 
app may want to decode the instruction to get the immediate and then 
execute different actions depending on its value (for instance to 
emulate some SMC call).

For this kind of app, it will be necessary to find out whether the 
condition check has failed or not before executing it.

Regards,

-- 
Julien Grall

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  reply	other threads:[~2016-06-06 15:54 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-02 22:52 [PATCH v5 1/9] vm_event: clear up return value of vm_event_monitor_traps Tamas K Lengyel
2016-06-02 22:52 ` [PATCH v5 2/9] monitor: Rename vm_event_monitor_get_capabilities Tamas K Lengyel
2016-06-17 19:07   ` Tamas K Lengyel
2016-06-21  9:20   ` Julien Grall
2016-06-02 22:52 ` [PATCH v5 3/9] monitor: Rename vm_event_monitor_guest_request Tamas K Lengyel
2016-06-17 19:10   ` Tamas K Lengyel
2016-06-21  9:18   ` Julien Grall
2016-06-02 22:52 ` [PATCH v5 4/9] monitor: Rename hvm/event to hvm/monitor Tamas K Lengyel
2016-06-02 22:52 ` [PATCH v5 5/9] monitor: ARM SMC events Tamas K Lengyel
2016-06-03  9:49   ` Julien Grall
2016-06-03 13:40     ` Tamas K Lengyel
2016-06-03 14:43       ` Julien Grall
2016-06-03 15:03         ` Tamas K Lengyel
2016-06-03 15:06           ` Julien Grall
2016-06-03 15:42             ` Tamas K Lengyel
2016-06-03 15:27         ` Tamas K Lengyel
2016-06-03 15:34           ` Tamas K Lengyel
2016-06-04  9:03             ` Edgar E. Iglesias
2016-06-04 17:40               ` Tamas K Lengyel
2016-06-06 10:07                 ` Julien Grall
     [not found]                   ` <CABfawh=tOsUP1dQi9oAZM+iy3rMmCKDW=VByT-L-xYdAMBiMKw@mail.gmail.com>
     [not found]                     ` <CABfawhkSXqky9WWp8NyKEUrH_ZzSJToxAncTeSYeKBg1q63rwg@mail.gmail.com>
2016-06-06 15:24                       ` Tamas K Lengyel
2016-06-06 15:54                         ` Julien Grall [this message]
2016-06-06 15:56                           ` Tamas K Lengyel
2016-06-06 16:14                             ` Tamas K Lengyel
2016-06-06 16:38                               ` Julien Grall
2016-06-06 17:28                                 ` Tamas K Lengyel
2016-06-07  7:13                                 ` Jan Beulich
2016-06-07 10:30                                   ` Stefano Stabellini
2016-06-07 16:06                                     ` Tamas K Lengyel
2016-06-02 22:52 ` [PATCH v5 6/9] arm/vm_event: get/set registers Tamas K Lengyel
2016-06-03 10:34   ` Jan Beulich
2016-06-03 19:27     ` Tamas K Lengyel
2016-06-02 22:52 ` [PATCH v5 7/9] tools/libxc: add xc_monitor_privileged_call Tamas K Lengyel
2016-06-02 22:52 ` [PATCH v5 8/9] x86/vm_event: Add HVM debug exception vm_events Tamas K Lengyel
2016-06-03 10:49   ` Jan Beulich
2016-06-03 13:29     ` Tamas K Lengyel
2016-06-03 14:23       ` Jan Beulich
2016-06-03 14:34         ` Tamas K Lengyel
2016-06-03 14:45           ` Jan Beulich
2016-06-03 14:51             ` Tamas K Lengyel
2016-06-02 22:52 ` [PATCH v5 9/9] tools/xen-access: add test-case for ARM SMC Tamas K Lengyel
2016-06-03  7:08 ` [PATCH v5 1/9] vm_event: clear up return value of vm_event_monitor_traps Razvan Cojocaru
2016-06-03 15:54 ` Jan Beulich
2016-06-03 16:03   ` Tamas K Lengyel
2016-06-17 19:09 ` Tamas K Lengyel
2016-06-24 10:58   ` Tian, Kevin

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