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:   Wed, 26 Oct 2022 15:17:18 +0000
From:   Wei Liu <wei.liu@kernel.org>
To:     Zhao Liu <zhao1.liu@linux.intel.com>
Cc:     "K . Y . Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H . Peter Anvin" <hpa@zytor.com>, linux-hyperv@vger.kernel.org,
        linux-kernel@vger.kernel.org, Ira Weiny <ira.weiny@intel.com>,
        "Fabio M . De Francesco" <fmdefrancesco@gmail.com>,
        Zhenyu Wang <zhenyu.z.wang@intel.com>,
        Zhao Liu <zhao1.liu@intel.com>
Subject: Re: [PATCH v2] x86/hyperv: Remove BUG_ON() for kmap_local_page()
Message-ID: <Y1lPfphHVRn2e4I5@liuwe-devbox-debian-v2>
References: <20221020083820.2341088-1-zhao1.liu@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20221020083820.2341088-1-zhao1.liu@linux.intel.com>
Precedence: bulk

On Thu, Oct 20, 2022 at 04:38:20PM +0800, Zhao Liu wrote:
> From: Zhao Liu <zhao1.liu@intel.com>
> 
> The commit 154fb14df7a3c ("x86/hyperv: Replace kmap() with
> kmap_local_page()") keeps the BUG_ON() to check if kmap_local_page()
> fails.
> 
> But in fact, kmap_local_page() always returns a valid kernel address
> and won't return NULL here. It will BUG on its own if it fails. [1]
> 
> So directly use memcpy_to_page() which creates local mapping to copy.
> 
> [1]: https://lore.kernel.org/lkml/YztFEyUA48et0yTt@iweiny-mobl/
> 
> Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> Suggested-by: Ira Weiny <ira.weiny@intel.com>
> Reviewed-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>

Applied to hyperv-fixes. Thanks.