From patchwork Mon Jun 13 16:16:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anirudh Rayabharam X-Patchwork-Id: 12879954 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 E213FC43334 for ; Mon, 13 Jun 2022 19:00:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242563AbiFMTAa (ORCPT ); Mon, 13 Jun 2022 15:00:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242889AbiFMTAO (ORCPT ); Mon, 13 Jun 2022 15:00:14 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id A82598AE7C; Mon, 13 Jun 2022 09:17:18 -0700 (PDT) Received: from anrayabh-desk.corp.microsoft.com (unknown [167.220.238.193]) by linux.microsoft.com (Postfix) with ESMTPSA id 7A83620BA5A7; Mon, 13 Jun 2022 09:17:12 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 7A83620BA5A7 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1655137038; bh=meFGhXThMYkI6bGmOB3JmL0xkuk9FE1Fwvyp0NbJeSc=; h=From:To:Cc:Subject:Date:From; b=UWsF5JAj6tMdsgcX03JWid8sisCep2p0cvz/KbyNaD4oswnfcT99qhcTudmpK3dfW KGK1d3gUrcAT8ymgpf/epPzlq75nSXZr+PkzC/0mVyQp/SEP/P7fym6ceV+WI8GOVR NJNmk+V37HTwyDUJAgnQE/0R/Z+bQq0jRxgwzBJw= From: Anirudh Rayabharam To: Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Ilias Stamatis , Maxim Levitsky Cc: mail@anirudhrb.com, kumarpraveen@linux.microsoft.com, Anirudh Rayabharam , wei.liu@kernel.org, robert.bradford@intel.com, liuwe@microsoft.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] KVM: nVMX: Don't expose TSC scaling to L1 when on Hyper-V Date: Mon, 13 Jun 2022 21:46:10 +0530 Message-Id: <20220613161611.3567556-1-anrayabh@linux.microsoft.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org VM entry into an L2 guest on KVM on Hyper-V fails with the following splat (stripped for brevity) when running cloud-hypervisor tests. [ 1481.600386] WARNING: CPU: 4 PID: 7641 at arch/x86/kvm/vmx/nested.c:4563 nested_vmx_vmexit+0x70d/0x790 [kvm_intel] [ 1481.600427] CPU: 4 PID: 7641 Comm: vcpu2 Not tainted 5.15.0-1008-azure #9-Ubuntu [ 1481.600429] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 07/22/2021 [ 1481.600430] RIP: 0010:nested_vmx_vmexit+0x70d/0x790 [kvm_intel] [ 1481.600447] Call Trace: [ 1481.600449] [ 1481.600451] nested_vmx_reflect_vmexit+0x10b/0x440 [kvm_intel] [ 1481.600457] __vmx_handle_exit+0xef/0x670 [kvm_intel] [ 1481.600467] vmx_handle_exit+0x12/0x50 [kvm_intel] [ 1481.600472] vcpu_enter_guest+0x83a/0xfd0 [kvm] [ 1481.600524] vcpu_run+0x5e/0x240 [kvm] [ 1481.600560] kvm_arch_vcpu_ioctl_run+0xd7/0x550 [kvm] [ 1481.600597] kvm_vcpu_ioctl+0x29a/0x6d0 [kvm] [ 1481.600634] __x64_sys_ioctl+0x91/0xc0 [ 1481.600637] do_syscall_64+0x5c/0xc0 [ 1481.600667] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 1481.600670] RIP: 0033:0x7f688becdaff [ 1481.600686] As per the comments in arch/x86/kvm/vmx/evmcs.h, TSC multiplier field is currently not supported in EVMCS. As a result, there is no TSC scaling support when KVM is running on Hyper-V i.e. kvm_has_tsc_control is false. However, in nested_vmx_setup_ctls_msrs(), TSC scaling is exposed to L1. When L1 tries to launch an L2 guest, vmcs12 has TSC scaling enabled. This propagates to vmcs02. But KVM doesn't set the TSC multiplier value because kvm_has_tsc_control is false. Due to this, VM entry for L2 guest fails. (VM entry fails if "use TSC scaling" is 1 and TSC multiplier is 0.) To fix, expose TSC scaling to L1 only if kvm_has_tsc_control. Fixes: d041b5ea93352 ("KVM: nVMX: Enable nested TSC scaling") Signed-off-by: Anirudh Rayabharam --- arch/x86/kvm/vmx/nested.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index f5cb18e00e78..d773ddc6422b 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -6656,6 +6656,9 @@ void nested_vmx_setup_ctls_msrs(struct nested_vmx_msrs *msrs, u32 ept_caps) msrs->secondary_ctls_low, msrs->secondary_ctls_high); + if (!kvm_has_tsc_control) + msrs->secondary_ctls_high &= ~SECONDARY_EXEC_TSC_SCALING; + msrs->secondary_ctls_low = 0; msrs->secondary_ctls_high &= SECONDARY_EXEC_DESC | @@ -6667,8 +6670,7 @@ void nested_vmx_setup_ctls_msrs(struct nested_vmx_msrs *msrs, u32 ept_caps) SECONDARY_EXEC_RDRAND_EXITING | SECONDARY_EXEC_ENABLE_INVPCID | SECONDARY_EXEC_RDSEED_EXITING | - SECONDARY_EXEC_XSAVES | - SECONDARY_EXEC_TSC_SCALING; + SECONDARY_EXEC_XSAVES; /* * We can emulate "VMCS shadowing," even if the hardware