linux-kernel - Re: [PATCH v2] hyperv-tlfs: Change prefix of generic HV_REGISTER_* MSRs to HV_MSR

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Message-ID: <ZeVyAB96VIYCxfRh@liuwe-devbox-debian-v2>
Date: Mon, 4 Mar 2024 07:02:24 +0000
From: Wei Liu <wei.liu@...nel.org>
To: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
Cc: linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
	haiyangz@...rosoft.com, mhklinu@...look.com, kys@...rosoft.com,
	wei.liu@...nel.org, decui@...rosoft.com, catalin.marinas@....com,
	tglx@...utronix.de, daniel.lezcano@...aro.org, arnd@...db.de
Subject: Re: [PATCH v2] hyperv-tlfs: Change prefix of generic HV_REGISTER_*
 MSRs to HV_MSR_*

On Tue, Feb 20, 2024 at 06:55:33AM -0800, Nuno Das Neves wrote:
> The HV_REGISTER_ are used as arguments to hv_set/get_register(), which
> delegate to arch-specific mechanisms for getting/setting synthetic
> Hyper-V MSRs.
> 
> On arm64, HV_REGISTER_ defines are synthetic VP registers accessed via
> the get/set vp registers hypercalls. The naming matches the TLFS
> document, although these register names are not specific to arm64.
> 
> However, on x86 the prefix HV_REGISTER_ indicates Hyper-V MSRs accessed
> via rdmsrl()/wrmsrl(). This is not consistent with the TLFS doc, where
> HV_REGISTER_ is *only* used for used for VP register names used by
> the get/set register hypercalls.
> 
> To fix this inconsistency and prevent future confusion, change the
> arch-generic aliases used by callers of hv_set/get_register() to have
> the prefix HV_MSR_ instead of HV_REGISTER_.
> 
> Use the prefix HV_X64_MSR_ for the x86-only Hyper-V MSRs. On x86, the
> generic HV_MSR_'s point to the corresponding HV_X64_MSR_.
> 
> Move the arm64 HV_REGISTER_* defines to the asm-generic hyperv-tlfs.h,
> since these are not specific to arm64. On arm64, the generic HV_MSR_'s
> point to the corresponding HV_REGISTER_.
> 
> While at it, rename hv_get/set_registers() and related functions to
> hv_get/set_msr(), hv_get/set_nested_msr(), etc. These are only used for
> Hyper-V MSRs and this naming makes that clear.
> 
> Signed-off-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
> Reviewed-by: Wei Liu <wei.liu@...nel.org>
> Reviewed-by: Michael Kelley <mhklinux@...look.com>

Applied to hyperv-next. Thanks.