Re: [PATCH 1/2] xen/*/nospec: Provide common versions of evaluate_nospec/block_speculation

From: Jan Beulich <jbeulich@suse.com>
To: Oleksii <oleksii.kurochko@gmail.com>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	"Volodymyr Babchuk" <Volodymyr_Babchuk@epam.com>,
	"Bertrand Marquis" <bertrand.marquis@arm.com>,
	"Michal Orzel" <michal.orzel@amd.com>,
	"Shawn Anastasio" <sanastasio@raptorengineering.com>,
	Xen-devel <xen-devel@lists.xenproject.org>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Julien Grall" <julien@xen.org>
Subject: Re: [PATCH 1/2] xen/*/nospec: Provide common versions of evaluate_nospec/block_speculation
Date: Tue, 5 Mar 2024 16:43:39 +0100	[thread overview]
Message-ID: <3d585715-7729-4a5a-b4e4-c0eb96601882@suse.com> (raw)
In-Reply-To: <7df33568918536487ec75a05cd47cee128150c0c.camel@gmail.com>

On 05.03.2024 16:15, Oleksii wrote:
> I agree that upon examining the current state of the code around these
> functions, it appears safe to provide stubs. However, the reason my
> patch was rejected is that it may not be entirely safe, as Julien
> pointed out that even with Arm, some functions shouldn't be empty.
> 
> What I would like to propose is that it might be beneficial, at least
> in CONFIG_DEBUG=y, to have a warning message. Does that make sense?

A warning message to what effect? And are you thinking of a build-time
warning, or a runtime one? Plus wouldn't different aspects quickly lead
to proliferation of warnings?

Jan