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 X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80FA7C433E9 for ; Fri, 15 Jan 2021 08:49:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5491023329 for ; Fri, 15 Jan 2021 08:49:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730602AbhAOItX (ORCPT ); Fri, 15 Jan 2021 03:49:23 -0500 Received: from mga03.intel.com ([134.134.136.65]:38651 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728177AbhAOItV (ORCPT ); Fri, 15 Jan 2021 03:49:21 -0500 IronPort-SDR: 1yQsMf2+rXVk2nhEDkx6zpgh2NlnhfG/5QZhhi7/ny8fT+0mWZ6AGXsrqhTV7nVqAMZpkeKe9O C8F8YiU16Tpw== X-IronPort-AV: E=McAfee;i="6000,8403,9864"; a="178606984" X-IronPort-AV: E=Sophos;i="5.79,349,1602572400"; d="scan'208";a="178606984" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jan 2021 00:47:32 -0800 IronPort-SDR: SHjVl41aTEVTO4rZxJx/ZKZScPvojw/NwJWqsSTros8GW98FNsywtZOvvFgy+0mGkf33kx9IhG cctqxceHsKRg== X-IronPort-AV: E=Sophos;i="5.79,349,1602572400"; d="scan'208";a="382590373" Received: from likexu-mobl1.ccr.corp.intel.com (HELO [10.238.4.93]) ([10.238.4.93]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jan 2021 00:47:29 -0800 Subject: Re: [PATCH] KVM: x86/pmu: Fix UBSAN shift-out-of-bounds warning in intel_pmu_refresh() From: Like Xu To: Paolo Bonzini , Sean Christopherson Cc: syzkaller-bugs@googlegroups.com, Vitaly Kuznetsov , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, Wanpeng Li , linux-kernel@vger.kernel.org References: <20201229071144.85418-1-like.xu@linux.intel.com> Organization: Intel OTC Message-ID: Date: Fri, 15 Jan 2021 16:47:27 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20201229071144.85418-1-like.xu@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ping ? On 2020/12/29 15:11, Like Xu wrote: > Since we know vPMU will not work properly when the guest bit_width(s) of > the [gp|fixed] counters are greater than the host ones, so we can setup a > smaller left shift value and refresh the guest pmu cpuid entry, thus fixing > the following UBSAN shift-out-of-bounds warning: > > shift exponent 197 is too large for 64-bit type 'long long unsigned int' > > Call Trace: > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x107/0x163 lib/dump_stack.c:120 > ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 > __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395 > intel_pmu_refresh.cold+0x75/0x99 arch/x86/kvm/vmx/pmu_intel.c:348 > kvm_vcpu_after_set_cpuid+0x65a/0xf80 arch/x86/kvm/cpuid.c:177 > kvm_vcpu_ioctl_set_cpuid2+0x160/0x440 arch/x86/kvm/cpuid.c:308 > kvm_arch_vcpu_ioctl+0x11b6/0x2d70 arch/x86/kvm/x86.c:4709 > kvm_vcpu_ioctl+0x7b9/0xdb0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3386 > vfs_ioctl fs/ioctl.c:48 [inline] > __do_sys_ioctl fs/ioctl.c:753 [inline] > __se_sys_ioctl fs/ioctl.c:739 [inline] > __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Reported-by: syzbot+ae488dc136a4cc6ba32b@syzkaller.appspotmail.com > Signed-off-by: Like Xu > --- > arch/x86/kvm/vmx/pmu_intel.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c > index a886a47daebd..a86a1690e75c 100644 > --- a/arch/x86/kvm/vmx/pmu_intel.c > +++ b/arch/x86/kvm/vmx/pmu_intel.c > @@ -345,6 +345,7 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu) > > pmu->nr_arch_gp_counters = min_t(int, eax.split.num_counters, > x86_pmu.num_counters_gp); > + eax.split.bit_width = min_t(int, eax.split.bit_width, x86_pmu.bit_width_gp); > pmu->counter_bitmask[KVM_PMC_GP] = ((u64)1 << eax.split.bit_width) - 1; > pmu->available_event_types = ~entry->ebx & > ((1ull << eax.split.mask_length) - 1); > @@ -355,6 +356,8 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu) > pmu->nr_arch_fixed_counters = > min_t(int, edx.split.num_counters_fixed, > x86_pmu.num_counters_fixed); > + edx.split.bit_width_fixed = min_t(int, > + edx.split.bit_width_fixed, x86_pmu.bit_width_fixed); > pmu->counter_bitmask[KVM_PMC_FIXED] = > ((u64)1 << edx.split.bit_width_fixed) - 1; > }