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([2001:b07:6468:f312:ac04:eef9:b257:b844]) by smtp.gmail.com with ESMTPSA id m10sm9686930wmf.40.2019.05.20.03.36.38 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Mon, 20 May 2019 03:36:38 -0700 (PDT) Subject: Re: [PATCH 4/4] KVM: nVMX: Fix using __this_cpu_read() in preemptible context To: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= References: <1558082990-7822-1-git-send-email-wanpengli@tencent.com> <1558082990-7822-4-git-send-email-wanpengli@tencent.com> From: Paolo Bonzini Message-ID: <4874aa09-7f46-7ca5-5d32-1d7b1cb1eef3@redhat.com> Date: Mon, 20 May 2019 12:36:37 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <1558082990-7822-4-git-send-email-wanpengli@tencent.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/05/19 10:49, Wanpeng Li wrote: > From: Wanpeng Li > > BUG: using __this_cpu_read() in preemptible [00000000] code: qemu-system-x86/4590 > caller is nested_vmx_enter_non_root_mode+0xebd/0x1790 [kvm_intel] > CPU: 4 PID: 4590 Comm: qemu-system-x86 Tainted: G OE 5.1.0-rc4+ #1 > Call Trace: > dump_stack+0x67/0x95 > __this_cpu_preempt_check+0xd2/0xe0 > nested_vmx_enter_non_root_mode+0xebd/0x1790 [kvm_intel] > nested_vmx_run+0xda/0x2b0 [kvm_intel] > handle_vmlaunch+0x13/0x20 [kvm_intel] > vmx_handle_exit+0xbd/0x660 [kvm_intel] > kvm_arch_vcpu_ioctl_run+0xa2c/0x1e50 [kvm] > kvm_vcpu_ioctl+0x3ad/0x6d0 [kvm] > do_vfs_ioctl+0xa5/0x6e0 > ksys_ioctl+0x6d/0x80 > __x64_sys_ioctl+0x1a/0x20 > do_syscall_64+0x6f/0x6c0 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Accessing per-cpu variable should disable preemption, this patch extends the > preemption disable region for __this_cpu_read(). > > Cc: Paolo Bonzini > Cc: Radim Krčmář > Signed-off-by: Wanpeng Li > --- > arch/x86/kvm/vmx/nested.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c > index 0c601d0..8f6f69c 100644 > --- a/arch/x86/kvm/vmx/nested.c > +++ b/arch/x86/kvm/vmx/nested.c > @@ -2792,14 +2792,13 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu) > : "cc", "memory" > ); > > - preempt_enable(); > - > if (vmx->msr_autoload.host.nr) > vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr); > if (vmx->msr_autoload.guest.nr) > vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.guest.nr); > > if (vm_fail) { > + preempt_enable(); > WARN_ON_ONCE(vmcs_read32(VM_INSTRUCTION_ERROR) != > VMXERR_ENTRY_INVALID_CONTROL_FIELD); > return 1; > @@ -2811,6 +2810,7 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu) > local_irq_enable(); > if (hw_breakpoint_active()) > set_debugreg(__this_cpu_read(cpu_dr7), 7); > + preempt_enable(); > > /* > * A non-failing VMEntry means we somehow entered guest mode with > Queued, thanks. Paolo