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Y . Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , Dexuan Cui , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Ira Weiny , "Fabio M . De Francesco" , Zhenyu Wang , Zhao Liu Subject: [PATCH v2] x86/hyperv: Remove BUG_ON() for kmap_local_page() Date: Thu, 20 Oct 2022 16:38:20 +0800 Message-Id: <20221020083820.2341088-1-zhao1.liu@linux.intel.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Spam-Status: No, score=-4.5 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_NONE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1747043721439523532?= X-GMAIL-MSGID: =?utf-8?q?1747195121530090004?= From: Zhao Liu 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 Suggested-by: Ira Weiny Reviewed-by: Ira Weiny Signed-off-by: Zhao Liu --- Change in v2: - Removed "Fixes" tag in patch message. --- arch/x86/hyperv/hv_init.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 29774126e931..f66c5709324f 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -459,13 +459,11 @@ void __init hyperv_init(void) wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); pg = vmalloc_to_page(hv_hypercall_pg); - dst = kmap_local_page(pg); src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE, MEMREMAP_WB); - BUG_ON(!(src && dst)); - memcpy(dst, src, HV_HYP_PAGE_SIZE); + BUG_ON(!src); + memcpy_to_page(pg, 0, src, HV_HYP_PAGE_SIZE); memunmap(src); - kunmap_local(dst); } else { hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg); wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);