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[2620:137:e000::1:20]) by mx.google.com with ESMTP id u11-20020a05640207cb00b00462848f0cdbsi3293227edy.299.2022.12.01.03.06.01; Thu, 01 Dec 2022 03:06:37 -0800 (PST) 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; Authentication-Results: mx.google.com; dkim=pass header.i=@linux.microsoft.com header.s=default header.b=pYkEj71o; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linux.microsoft.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231237AbiLALEr (ORCPT + 99 others); Thu, 1 Dec 2022 06:04:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229974AbiLALEC (ORCPT ); Thu, 1 Dec 2022 06:04:02 -0500 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 22F29A9CC3; Thu, 1 Dec 2022 03:03:52 -0800 (PST) Received: from jinankjain-dranzer.zrrkmle5drku1h0apvxbr2u2ee.ix.internal.cloudapp.net (unknown [20.188.121.5]) by linux.microsoft.com (Postfix) with ESMTPSA id EA86720B83C5; Thu, 1 Dec 2022 03:03:46 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com EA86720B83C5 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1669892631; bh=wqo8SKjqAvAPfB0JD2Zy4udGVJ0BdIhQjoIMI1f64Wg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pYkEj71o+8YSGOwx2H+WwoM1aJLHHM1c4qq8Mb68MP5EmrZZV88jXio965DtQkE8l BAoPrSsubSQ/IILsisHz1aLgon01UsZBsQ2Re21ykd2oJ+npmrpZKzmrnU3n4xJzkb HJ0P0WlxJYBUHuOWRNEVmy5cI+TplNzLI0/63NvE= From: Jinank Jain To: jinankjain@microsoft.com Cc: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, arnd@arndb.de, peterz@infradead.org, jpoimboe@kernel.org, jinankjain@linux.microsoft.com, seanjc@google.com, kirill.shutemov@linux.intel.com, ak@linux.intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, anrayabh@linux.microsoft.com, mikelley@microsoft.com Subject: [PATCH v7 1/5] x86/hyperv: Add support for detecting nested hypervisor Date: Thu, 1 Dec 2022 11:03:35 +0000 Message-Id: X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 X-Spam-Status: No, score=-19.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,ENV_AND_HDR_SPF_MATCH,RCVD_IN_DNSWL_MED, SPF_HELO_PASS,SPF_PASS,USER_IN_DEF_DKIM_WL,USER_IN_DEF_SPF_WL 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?1751009510360175214?= X-GMAIL-MSGID: =?utf-8?q?1751009510360175214?= Detect if Linux is running as a nested hypervisor in the root partition for Microsoft Hypervisor, using flags provided by MSHV. Expose a new variable hv_nested that is used later for decisions specific to the nested use case. Signed-off-by: Jinank Jain --- arch/x86/include/asm/hyperv-tlfs.h | 3 +++ arch/x86/kernel/cpu/mshyperv.c | 7 +++++++ drivers/hv/hv_common.c | 9 ++++++--- include/asm-generic/mshyperv.h | 1 + 4 files changed, 17 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h index 6d9368ea3701..58c03d18c235 100644 --- a/arch/x86/include/asm/hyperv-tlfs.h +++ b/arch/x86/include/asm/hyperv-tlfs.h @@ -114,6 +114,9 @@ /* Recommend using the newer ExProcessorMasks interface */ #define HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED BIT(11) +/* Indicates that the hypervisor is nested within a Hyper-V partition. */ +#define HV_X64_HYPERV_NESTED BIT(12) + /* Recommend using enlightened VMCS */ #define HV_X64_ENLIGHTENED_VMCS_RECOMMENDED BIT(14) diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 46668e255421..f9b78d4829e3 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -37,6 +37,8 @@ /* Is Linux running as the root partition? */ bool hv_root_partition; +/* Is Linux running on nested Microsoft Hypervisor */ +bool hv_nested; struct ms_hyperv_info ms_hyperv; #if IS_ENABLED(CONFIG_HYPERV) @@ -301,6 +303,11 @@ static void __init ms_hyperv_init_platform(void) pr_info("Hyper-V: running as root partition\n"); } + if (ms_hyperv.hints & HV_X64_HYPERV_NESTED) { + hv_nested = true; + pr_info("Hyper-V: running on a nested hypervisor\n"); + } + /* * Extract host information. */ diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c index ae68298c0dca..52a6f89ccdbd 100644 --- a/drivers/hv/hv_common.c +++ b/drivers/hv/hv_common.c @@ -25,17 +25,20 @@ #include /* - * hv_root_partition and ms_hyperv are defined here with other Hyper-V - * specific globals so they are shared across all architectures and are + * hv_root_partition, ms_hyperv and hv_nested are defined here with other + * Hyper-V specific globals so they are shared across all architectures and are * built only when CONFIG_HYPERV is defined. But on x86, * ms_hyperv_init_platform() is built even when CONFIG_HYPERV is not - * defined, and it uses these two variables. So mark them as __weak + * defined, and it uses these three variables. So mark them as __weak * here, allowing for an overriding definition in the module containing * ms_hyperv_init_platform(). */ bool __weak hv_root_partition; EXPORT_SYMBOL_GPL(hv_root_partition); +bool __weak hv_nested; +EXPORT_SYMBOL_GPL(hv_nested); + struct ms_hyperv_info __weak ms_hyperv; EXPORT_SYMBOL_GPL(ms_hyperv); diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h index bfb9eb9d7215..f131027830c3 100644 --- a/include/asm-generic/mshyperv.h +++ b/include/asm-generic/mshyperv.h @@ -48,6 +48,7 @@ struct ms_hyperv_info { u64 shared_gpa_boundary; }; extern struct ms_hyperv_info ms_hyperv; +extern bool hv_nested; extern void * __percpu *hyperv_pcpu_input_arg; extern void * __percpu *hyperv_pcpu_output_arg;