linux-kernel - Re: [PATCH] x86/hyperv: Export hv_hypercall

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Message-ID: <aKwrgVCtv_FkiuVn@infradead.org>
Date: Mon, 25 Aug 2025 02:23:13 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Naman Jain <namjain@...ux.microsoft.com>
Cc: "K . Y . Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	"H . Peter Anvin" <hpa@...or.com>, linux-hyperv@...r.kernel.org,
	linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] x86/hyperv: Export hv_hypercall_pg unconditionally

On Mon, Aug 25, 2025 at 11:22:08AM +0530, Naman Jain wrote:
> With commit 0e20f1f4c2cb ("x86/hyperv: Clean up hv_do_hypercall()"),
> config checks were added to conditionally restrict export
> of hv_hypercall_pg symbol at the same time when a usage of that symbol
> was added in mshv_vtl_main.c driver. This results in missing symbol
> warning when mshv_vtl_main is compiled. Change the logic to
> export it unconditionally.

Note that exporting variables like this always is a bad idea only
used as a last resort.  It would be much better to just build a proper
API for using it instead.