From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6BA6AC43217 for ; Thu, 17 Nov 2022 03:28:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234348AbiKQD2M (ORCPT ); Wed, 16 Nov 2022 22:28:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49912 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234291AbiKQD2J (ORCPT ); Wed, 16 Nov 2022 22:28:09 -0500 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 1024C66CBB; Wed, 16 Nov 2022 19:28:09 -0800 (PST) Received: from jinankjain-dranzer.zrrkmle5drku1h0apvxbr2u2ee.ix.internal.cloudapp.net (unknown [20.188.121.5]) by linux.microsoft.com (Postfix) with ESMTPSA id 936BF20B83C2; Wed, 16 Nov 2022 19:28:04 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 936BF20B83C2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1668655688; bh=jZrfE3E4lxhGw+MvJUCDK70VJfmkQMf6oCsKZEKTHbw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AhZJQoJKWB6Zq8JekSMD2eVo22xwkk2U8ruFr3WROsH4/SxcCgHVp19lvtyGC5Z9L +KKIJXC3FuVvz1qmcovAgDZoiWa4W3zPvXjooVekxfXmXNNzgI/loaneZJtzYkqb8g xm1bCXnlH157B0iuRJz6cMoHHF7YGgQ8gazrfvP0= 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 v4 1/5] x86/hyperv: Add support for detecting nested hypervisor Date: Thu, 17 Nov 2022 03:27:54 +0000 Message-Id: <08ab7aede41f2feb1cd8ac21d0ddd17e25b1d070.1668618583.git.jinankjain@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org When Linux runs as a root partition for Microsoft Hypervisor. It is possible to detect if it is running as nested hypervisor using hints exposed by mshv. While at it expose a new variable called hv_nested which can be used later for making decisions specific to nested use case. Signed-off-by: Jinank Jain --- arch/arm64/hyperv/mshyperv.c | 6 ++++++ arch/x86/include/asm/hyperv-tlfs.h | 3 +++ arch/x86/kernel/cpu/mshyperv.c | 7 +++++++ drivers/hv/hv_common.c | 7 +++++-- include/asm-generic/mshyperv.h | 1 + 5 files changed, 22 insertions(+), 2 deletions(-) diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c index a406454578f0..2024b19dc514 100644 --- a/arch/arm64/hyperv/mshyperv.c +++ b/arch/arm64/hyperv/mshyperv.c @@ -19,6 +19,9 @@ static bool hyperv_initialized; +/* Is Linux running on nested Microsoft Hypervisor */ +bool hv_nested; + static int __init hyperv_init(void) { struct hv_get_vp_registers_output result; @@ -63,6 +66,9 @@ static int __init hyperv_init(void) pr_info("Hyper-V: Host Build %d.%d.%d.%d-%d-%d\n", b >> 16, b & 0xFFFF, a, d & 0xFFFFFF, c, d >> 24); + /* ARM64 does not support nested virtualization */ + hv_nested = false; + ret = hv_common_init(); if (ret) return ret; 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 831613959a92..9a4204139490 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..dcb336ce374f 100644 --- a/drivers/hv/hv_common.c +++ b/drivers/hv/hv_common.c @@ -25,8 +25,8 @@ #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 @@ -36,6 +36,9 @@ 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..5df6e944e6a9 100644 --- a/include/asm-generic/mshyperv.h +++ b/include/asm-generic/mshyperv.h @@ -164,6 +164,7 @@ extern int vmbus_interrupt; extern int vmbus_irq; extern bool hv_root_partition; +extern bool hv_nested; #if IS_ENABLED(CONFIG_HYPERV) /* -- 2.25.1