From: Julien Grall <julien.grall@arm.com>
To: Razvan Cojocaru <rcojocaru@bitdefender.com>,
Tamas K Lengyel <tamas@tklengyel.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
Keir Fraser <keir@xen.org>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Ian Jackson <ian.jackson@eu.citrix.com>,
Jan Beulich <jbeulich@suse.com>,
Xen-devel <xen-devel@lists.xenproject.org>,
wei.liu2@citrix.com
Subject: Re: [PATCH v2 2/5] vm_event: Implement ARM SMC events
Date: Wed, 4 May 2016 15:03:31 +0100 [thread overview]
Message-ID: <572A0133.20501@arm.com> (raw)
In-Reply-To: <f68b6275-e698-9c6e-11f6-7cc2a2706672@bitdefender.com>
On 04/05/2016 14:30, Razvan Cojocaru wrote:
> On 05/04/2016 04:26 PM, Julien Grall wrote:
>> I may misunderstand some parts of the vm event subsystem. To get/set the
>> full set of registers, the user will have to use the
>> DOMCTL_{set,get}vcpucontext, correct? So why does Xen expose a part of
>> the vCPU context through the vm_event?
>
> Because DOMCTL_{set,get}vcpucontext is expensive, and a serious
> introspection application will receive hundreds or thousands of events
> per second.
>
> Having what's most commonly needed being sent with the vm_event
> eliminates the need for extra hypercalls and can make the difference
> between a responsive and an unusable userspace introspection application.
Thank you for the explanation. So in this case, we should also make x16
(AArch64) and r12 (AArch32) available as they will be used for hypercall.
Regards,
--
Julien Grall
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next prev parent reply other threads:[~2016-05-04 14:03 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-29 18:07 [PATCH v2 1/5] monitor: Rename vm_event_monitor_get_capabilities Tamas K Lengyel
2016-04-29 18:07 ` [PATCH v2 2/5] vm_event: Implement ARM SMC events Tamas K Lengyel
2016-04-29 20:07 ` Razvan Cojocaru
2016-04-29 20:12 ` Tamas K Lengyel
2016-04-29 20:27 ` Tamas K Lengyel
2016-04-29 20:32 ` Razvan Cojocaru
2016-05-02 10:35 ` Wei Liu
2016-05-03 11:31 ` Julien Grall
2016-05-03 18:48 ` Tamas K Lengyel
2016-05-04 10:31 ` Julien Grall
[not found] ` <CABfawhmwVQyYeGYMxKTb1zMUkyOSutMwm4bkTxoeNaFTmGuyXA@mail.gmail.com>
[not found] ` <CABfawhmVUyqcuoxitKrXxcg93yLY4e8H7S1A_GEFbX3+Vb-hrA@mail.gmail.com>
2016-05-04 12:42 ` Tamas K Lengyel
2016-05-04 13:26 ` Julien Grall
2016-05-04 13:30 ` Razvan Cojocaru
2016-05-04 14:03 ` Julien Grall [this message]
2016-05-04 14:08 ` Tamas K Lengyel
2016-04-29 18:07 ` [PATCH v2 3/5] x86/hvm: Rename hvm/event to hvm/monitor Tamas K Lengyel
2016-05-04 1:13 ` Tian, Kevin
2016-04-29 18:07 ` [PATCH v2 4/5] x86/hvm: Add debug exception vm_events Tamas K Lengyel
2016-05-02 13:12 ` Jan Beulich
2016-05-02 15:35 ` Tamas K Lengyel
2016-05-02 15:40 ` Jan Beulich
2016-05-02 15:45 ` Tamas K Lengyel
2016-04-29 18:07 ` [PATCH v2 5/5] MAINTAINERS: Update monitor/vm_event covered code Tamas K Lengyel
2016-05-02 13:00 ` Jan Beulich
2016-05-03 8:18 ` Jan Beulich
2016-05-03 8:20 ` Razvan Cojocaru
2016-05-03 8:26 ` Jan Beulich
2016-05-03 9:09 ` Wei Liu
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