From: Julien Grall <julien.grall@arm.com>
To: Tamas K Lengyel <tamas@tklengyel.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
Stefano Stabellini <sstabellini@kernel.org>
Subject: Re: [PATCH v4 4/8] monitor: ARM SMC events
Date: Tue, 5 Jul 2016 10:58:56 +0100 [thread overview]
Message-ID: <577B84E0.1040700@arm.com> (raw)
In-Reply-To: <CABfawh=cXDxNtY4fA+uUraU=nncW800V+P5V=4WY-Dsy8rigfQ@mail.gmail.com>
Hello Tamas,
On 04/07/16 22:05, Tamas K Lengyel wrote:
> On Mon, Jul 4, 2016 at 2:02 PM, Julien Grall <julien.grall@arm.com> wrote:
>>
>>
>> On 04/07/2016 20:13, Tamas K Lengyel wrote:
>>>>
>>>> On ARMv8, ESR_EL2.ISS has a different encoding depending on the state
>>>> (i.e
>>>> AArch64 or AArch32). See D7-1861 in ARM DDI 0487A.i. Furthermore, in
>>>> AArch32
>>>> state, the ARMv8 specs permits to trap conditional SMC instructions that
>>>> fail their condition check (see D7-1897 in ARM DDI 0406C.c).
[...]
>>> I'm unable to find the reference you mention about conditional SMCs
>>> generating Hyp traps even if they fail their condition checks on
>>> certain implementations. The only references I find in ARMv8 manual
>>> states explicitly that "The trap that HCR_EL2.TSC enables traps the
>>> attempted execution of a conditional SMC instruction only if the
>>> instruction passes its condition code check" (D1.15) and "The
>>> architecture requires that a Hyp trap on a conditional SMC instruction
>>> generates an exception only if the instruction passes its condition
>>> code check, see Trapping use of the SMC instruction on page G1-3510"
>>> (G1.16).
>>
>>
>> If you look at description of HCR_EL2.TSC at D7-1973 in DDI 0487A.j;
>> "In AArch32 state, the ARMv8-A architecture permits, but does not require,
>> this trap to apply to conditional SMC instructions that fail their condition
>> code check, in the same way as with traps on
>> other conditional instructions."
>>
>> AFAICT the change was already present in the ARM ARM beginning of 2015. So I
>> suspect you are using an old version of the spec. In general, I would
>> recommend you to use the most recent spec for your development.
>>
>> For future question related to the spec, please mention the version of the
>> spec you quote. It makes easier to find out what is going on.
>
> Ah yes, indeed, I was looking at an older version. From the manual
> though it is not clear to me how we can differentiate SMCs that had
> their condition check fail from the others once its trapped to the
> VMM..
It would be very similar to how Xen is checking if a conditional
instruction fails its condition check (see check_conditional_instr).
> Are you still planning to implement that filter?
It is in my todo list, however at the moment it towards the end. Feel
free to send patch yourself.
Regards,
--
Julien Grall
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next prev parent reply other threads:[~2016-07-05 9:59 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-29 22:37 [PATCH v4 1/8] monitor: Rename vm_event_monitor_get_capabilities Tamas K Lengyel
2016-05-29 22:37 ` [PATCH v4 2/8] monitor: Rename vm_event_monitor_guest_request Tamas K Lengyel
2016-05-30 7:05 ` Razvan Cojocaru
2016-05-30 13:51 ` Jan Beulich
2016-05-29 22:37 ` [PATCH v4 3/8] monitor: Rename hvm/event to hvm/monitor Tamas K Lengyel
2016-05-30 7:08 ` Razvan Cojocaru
2016-05-30 13:53 ` Jan Beulich
2016-05-29 22:37 ` [PATCH v4 4/8] monitor: ARM SMC events Tamas K Lengyel
2016-06-01 11:37 ` Julien Grall
[not found] ` <CABfawhmO9tUG3-OcorfwqdOgZTkjoUk+u=dHySGonBDvobqyKw@mail.gmail.com>
[not found] ` <CABfawhmK2GAmQqZMhrgjYzeUZ_XaoyRUPuJxyPK5LJEHwsp5SA@mail.gmail.com>
[not found] ` <CABfawh=J1fwinTYKGvJNrFPOsGLSXz6U3GE8fxPz3-KsXSWfbQ@mail.gmail.com>
[not found] ` <CABfawhn7zvE=hn0hq1ryH+sW-jdkAXgZM1C2KxwZVUE8pbp8cQ@mail.gmail.com>
2016-06-01 15:41 ` Tamas K Lengyel
2016-06-02 14:23 ` Julien Grall
2016-06-02 22:31 ` Tamas K Lengyel
2016-07-04 19:13 ` Tamas K Lengyel
2016-07-04 20:02 ` Julien Grall
2016-07-04 21:05 ` Tamas K Lengyel
2016-07-05 9:58 ` Julien Grall [this message]
2016-05-29 22:37 ` [PATCH v4 5/8] arm/vm_event: get/set registers Tamas K Lengyel
2016-05-30 7:09 ` Razvan Cojocaru
2016-05-30 11:50 ` Jan Beulich
2016-05-30 19:47 ` Tamas K Lengyel
2016-05-30 20:20 ` Julien Grall
2016-05-30 20:37 ` Tamas K Lengyel
2016-05-30 20:46 ` Razvan Cojocaru
2016-05-30 20:53 ` Tamas K Lengyel
2016-05-30 21:35 ` Julien Grall
2016-05-30 21:41 ` Tamas K Lengyel
2016-05-31 7:54 ` Jan Beulich
2016-05-31 8:06 ` Razvan Cojocaru
2016-05-31 8:30 ` Jan Beulich
2016-05-31 16:20 ` Tamas K Lengyel
2016-05-31 7:48 ` Jan Beulich
2016-05-31 16:28 ` Tamas K Lengyel
2016-06-01 8:41 ` Jan Beulich
2016-06-01 11:24 ` Julien Grall
2016-06-01 18:21 ` Tamas K Lengyel
2016-06-01 19:34 ` Razvan Cojocaru
2016-06-01 19:43 ` Julien Grall
2016-06-02 7:35 ` Jan Beulich
2016-06-02 8:26 ` Razvan Cojocaru
2016-06-02 9:38 ` Jan Beulich
2016-06-02 9:42 ` Razvan Cojocaru
2016-06-01 19:38 ` Julien Grall
2016-06-01 19:49 ` Julien Grall
2016-06-01 19:50 ` Tamas K Lengyel
2016-05-29 22:37 ` [PATCH v4 6/8] tools/libxc: add xc_monitor_privileged_call Tamas K Lengyel
2016-05-29 22:37 ` [PATCH v4 7/8] tools/xen-access: add test-case for ARM SMC Tamas K Lengyel
2016-05-30 9:56 ` Wei Liu
2016-05-29 22:37 ` [PATCH v4 8/8] x86/vm_event: Add HVM debug exception vm_events Tamas K Lengyel
2016-05-30 7:29 ` Razvan Cojocaru
2016-05-30 14:16 ` Jan Beulich
2016-05-30 20:13 ` Tamas K Lengyel
2016-05-30 20:58 ` Andrew Cooper
2016-05-31 7:59 ` Jan Beulich
2016-06-01 21:46 ` Tamas K Lengyel
2016-06-01 22:17 ` Andrew Cooper
2016-06-02 0:01 ` Tamas K Lengyel
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