From: Julien Grall <julien.grall@arm.com>
To: Andrii Anisov <andrii.anisov@gmail.com>, Jan Beulich <JBeulich@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
Wei Liu <wei.liu2@citrix.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
George Dunlap <George.Dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Ian Jackson <Ian.Jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>,
xen-devel <xen-devel@lists.xenproject.org>,
"andrii_anisov@epam.com" <andrii_anisov@epam.com>,
Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH v3] xen: introduce VCPUOP_register_runstate_phys_memory_area hypercall
Date: Fri, 14 Jun 2019 15:39:37 +0100 [thread overview]
Message-ID: <a439c5ec-cec5-51be-bf76-eebdf50cf1bb@arm.com> (raw)
In-Reply-To: <90a3c768-5274-dbb8-8eb2-2eda902c3e5b@gmail.com>
On 14/06/2019 15:36, Andrii Anisov wrote:
> Hello Julien,
Hi,
> On 13.06.19 17:41, Julien Grall wrote:
>> Sorry I may have missed it. We can't really restrict the usage of the current
>> hypercall (it is pretty lax). So I think any lockless solution would require
>> to allow the hypercall
>> to be used together (which I want to avoid).
>
> I'd better say here allowing using phys and virt registered runstates together
> (and independently).
> And me personally for this approach, for sure not encouraging users (guests) to
> do so.
Why? What are the benefits for a guest to use the two interface together? After
all they have exactly the same data...
>
>> If we agree to allow the two hypercalls to be used together, then if we
>> protect the update with domain_lock() then you should be able to avoid any
>> race with the update path as onlining a vCPU requires to take the
>> domain_lock() (see do_vcpu_op for x86 and do_common_cpu_on for Arm).
>
> Could you please clarify are you saying about protection runstate mapping update
> or runstate values update?
runstate mapping.
> BTW, I'm a bit confused, are you OK with lock (not trylock) existing in hypercall?
This is still in discussion.
Cheers,
--
Julien Grall
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next prev parent reply other threads:[~2019-06-14 14:39 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-24 18:12 [PATCH RFC 2] [DO NOT APPLY] introduce VCPUOP_register_runstate_phys_memory_area hypercall Andrii Anisov
2019-05-24 18:12 ` [Xen-devel] " Andrii Anisov
2019-05-24 18:12 ` [PATCH v3] Introduce runstate area registration with phys address Andrii Anisov
2019-05-24 18:12 ` [Xen-devel] " Andrii Anisov
2019-05-24 18:12 ` [PATCH v3] xen: introduce VCPUOP_register_runstate_phys_memory_area hypercall Andrii Anisov
2019-05-24 18:12 ` [Xen-devel] " Andrii Anisov
2019-06-07 14:23 ` Jan Beulich
2019-06-10 11:44 ` Julien Grall
2019-06-11 9:10 ` Jan Beulich
2019-06-11 10:22 ` Andrii Anisov
2019-06-11 12:12 ` Julien Grall
2019-06-11 12:26 ` Andrii Anisov
2019-06-11 12:32 ` Julien Grall
2019-06-11 12:40 ` Andrii Anisov
2019-06-13 12:21 ` Andrii Anisov
2019-06-13 12:39 ` Jan Beulich
2019-06-13 12:32 ` Andrii Anisov
2019-06-13 12:41 ` Jan Beulich
2019-06-13 12:48 ` Julien Grall
2019-06-13 12:58 ` Jan Beulich
2019-06-13 13:14 ` Julien Grall
2019-06-13 13:40 ` Jan Beulich
2019-06-13 14:41 ` Julien Grall
2019-06-14 14:36 ` Andrii Anisov
2019-06-14 14:39 ` Julien Grall [this message]
2019-06-14 15:11 ` Andrii Anisov
2019-06-14 15:24 ` Julien Grall
2019-06-14 16:11 ` Andrii Anisov
2019-06-14 16:20 ` Julien Grall
2019-06-14 16:25 ` Andrii Anisov
2019-06-17 6:27 ` Jan Beulich
2019-06-14 15:42 ` Jan Beulich
2019-06-14 16:23 ` Andrii Anisov
2019-06-17 6:28 ` Jan Beulich
2019-06-18 15:32 ` Andrii Anisov
2019-06-18 15:44 ` Jan Beulich
2019-06-11 16:09 ` Andrii Anisov
2019-06-12 7:27 ` Jan Beulich
2019-06-13 12:17 ` Andrii Anisov
2019-06-13 12:36 ` Jan Beulich
2019-06-11 16:13 ` Andrii Anisov
2019-05-24 18:12 ` [PATCH RFC 1] [DO NOT APPLY] " Andrii Anisov
2019-05-24 18:12 ` [Xen-devel] " Andrii Anisov
2019-05-28 8:59 ` [PATCH RFC 2] " Julien Grall
2019-05-28 8:59 ` [Xen-devel] " Julien Grall
2019-05-28 9:17 ` Andrii Anisov
2019-05-28 9:17 ` [Xen-devel] " Andrii Anisov
2019-05-28 9:23 ` Julien Grall
2019-05-28 9:23 ` [Xen-devel] " Julien Grall
2019-05-28 9:36 ` Andrii Anisov
2019-05-28 9:36 ` [Xen-devel] " Andrii Anisov
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