From: Jan Beulich <jbeulich@suse.com>
To: Henry Wang <xin.wang2@amd.com>
Cc: Anthony PERARD <anthony.perard@citrix.com>,
Juergen Gross <jgross@suse.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
George Dunlap <george.dunlap@citrix.com>,
Julien Grall <julien@xen.org>,
Stefano Stabellini <sstabellini@kernel.org>,
Bertrand Marquis <bertrand.marquis@arm.com>,
Michal Orzel <michal.orzel@amd.com>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
Alec Kwapis <alec.kwapis@medtronic.com>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH 2/3] xen/arm, tools: Add a new HVM_PARAM_MAGIC_BASE_PFN key in HVMOP
Date: Fri, 26 Apr 2024 08:50:33 +0200 [thread overview]
Message-ID: <9825c488-0acd-412b-894a-b683525b1592@suse.com> (raw)
In-Reply-To: <c49cbaef-101e-444d-b202-2f1f34beb390@amd.com>
On 26.04.2024 08:30, Henry Wang wrote:
> On 4/26/2024 2:21 PM, Jan Beulich wrote:
>> On 26.04.2024 05:14, Henry Wang wrote:
>>> --- a/xen/include/public/hvm/params.h
>>> +++ b/xen/include/public/hvm/params.h
>>> @@ -76,6 +76,7 @@
>>> */
>>> #define HVM_PARAM_STORE_PFN 1
>>> #define HVM_PARAM_STORE_EVTCHN 2
>>> +#define HVM_PARAM_MAGIC_BASE_PFN 3
>>>
>>> #define HVM_PARAM_IOREQ_PFN 5
>> Considering all adjacent values are used, it is overwhelmingly likely that
>> 3 was once used, too. Such re-use needs to be done carefully. Since you
>> need this for Arm only, that's likely okay, but doesn't go without (a)
>> saying and (b) considering the possible future case of dom0less becoming
>> arch-agnostic, or hyperlaunch wanting to extend the scope. Plus (c) imo
>> this also needs at least a comment, maybe even an #ifdef, seeing how x86-
>> focused most of the rest of this header is.
>
> Thanks for the feedback. These make sense. I think probably
> dom0less/hyperlaunch will have similar use cases so the number 3 can be
> reused at that time. Therefore, in v2, I will add more description in
> commit message, a comment on top of this macro and protect it with
> #ifdef. Hope this will address your concern. Thanks.
FTAOD: If you foresee re-use by hyperlaunch, re-using a previously used
number may need re-considering. Which isn't to say that number re-use is
excluded here, but it would need at least figuring out (and then stating)
what exactly the number was used for and until when.
Jan
next prev parent reply other threads:[~2024-04-26 6:50 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 3:14 [PATCH 0/3] Guest magic region allocation for 11 Dom0less domUs - Take two Henry Wang
2024-04-26 3:14 ` [PATCH 1/3] xen/arm/dom0less-build: Alloc magic pages for Dom0less DomUs from hypervisor Henry Wang
2024-04-30 0:27 ` Daniel P. Smith
2024-04-30 2:55 ` Henry Wang
2024-04-30 10:22 ` Daniel P. Smith
2024-05-06 3:13 ` Henry Wang
2024-05-10 7:37 ` Michal Orzel
2024-05-10 7:42 ` Henry Wang
2024-04-26 3:14 ` [PATCH 2/3] xen/arm, tools: Add a new HVM_PARAM_MAGIC_BASE_PFN key in HVMOP Henry Wang
2024-04-26 6:21 ` Jan Beulich
2024-04-26 6:30 ` Henry Wang
2024-04-26 6:50 ` Jan Beulich [this message]
2024-04-26 7:02 ` Henry Wang
2024-04-30 0:31 ` Daniel P. Smith
2024-04-30 2:51 ` Henry Wang
2024-04-30 6:11 ` Jan Beulich
2024-04-30 8:12 ` Henry Wang
2024-04-30 8:51 ` Jan Beulich
2024-04-30 0:35 ` Daniel P. Smith
2024-04-30 1:25 ` Daniel P. Smith
2024-05-02 18:08 ` Stefano Stabellini
2024-05-06 2:01 ` Henry Wang
2024-04-26 3:14 ` [PATCH 3/3] tools/init-dom0less: Avoid hardcoding GUEST_MAGIC_BASE Henry Wang
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