Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 3 Aug 2023 01:25:34 +0000
From:   Wei Liu <wei.liu@kernel.org>
To:     Nuno Das Neves <nunodasneves@linux.microsoft.com>
Cc:     linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
        x86@kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-arch@vger.kernel.org, mikelley@microsoft.com,
        kys@microsoft.com, wei.liu@kernel.org, haiyangz@microsoft.com,
        decui@microsoft.com, ssengar@linux.microsoft.com,
        mukeshrathor@microsoft.com, stanislav.kinsburskiy@gmail.com,
        jinankjain@linux.microsoft.com, apais@linux.microsoft.com,
        Tianyu.Lan@microsoft.com, vkuznets@redhat.com, tglx@linutronix.de,
        mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
        hpa@zytor.com, will@kernel.org, catalin.marinas@arm.com
Subject: Re: [PATCH 01/15] hyperv-tlfs: Change shared HV_REGISTER_* defines
 to HV_MSR_*
Message-ID: <ZMsCDk68qo3WDcUo@liuwe-devbox-debian-v2>
References: <1690487690-2428-1-git-send-email-nunodasneves@linux.microsoft.com>
 <1690487690-2428-2-git-send-email-nunodasneves@linux.microsoft.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1690487690-2428-2-git-send-email-nunodasneves@linux.microsoft.com>
Precedence: bulk

On Thu, Jul 27, 2023 at 12:54:36PM -0700, Nuno Das Neves wrote:
> In x86 hyperv-tlfs, HV_REGISTER_ prefix is used to indicate MSRs
> accessed via rdmsrl/wrmsrl. But in ARM64, HV_REGISTER_ instead indicates
> VP registers accessed via get/set vp registers hypercall.
> 
> This is due to HV_REGISTER_* names being used by hv_set/get_register,
> with the arch-specific version delegating to the appropriate mechanism.
> 
> The problem is, using prefix HV_REGISTER_ for MSRs will conflict with
> VP registers when they are introduced for x86 in future.
> 
> This patch solves the issue by:
> 
> 1. Defining all the x86 MSRs with a consistent prefix: HV_X64_MSR_.
>    This is so HV_REGISTER_ can be reserved for VP registers.
> 
> 2. Change the non-arch-specific alias used by hv_set/get_register to
>    HV_MSR_. This is also happens to be the same name HyperV uses for this
>    purpose.
> 
> Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>

Assuming the prior (private?) discussion with Michael led to this patch:

Acked-by: Wei Liu <wei.liu@kernel.org>