From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751963AbdEDJhz (ORCPT ); Thu, 4 May 2017 05:37:55 -0400 Received: from mail-pg0-f65.google.com ([74.125.83.65]:36003 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750865AbdEDJhp (ORCPT ); Thu, 4 May 2017 05:37:45 -0400 From: Wanpeng Li X-Google-Original-From: Wanpeng Li To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Wanpeng Li , "Michael S . Tsirkin" , Alexander Graf , "Gabriel L. Somlo" Subject: [PATCH] KVM: nVMX: fix MWAIT emulation for guests Date: Thu, 4 May 2017 02:37:28 -0700 Message-Id: <1493890648-9277-1-git-send-email-wanpeng.li@hotmail.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wanpeng Li The kvm-unit-tests/vmx.flat fails against instruction(mwait) intercept test. Test suite: instruction intercept Unhandled exception 13 #GP at ip 0000000000402397 error_code=0000 rflags=00010012 cs=00000008 rax=0000000000000000 rcx=0000000004006172 rdx=0000000000402397 rbx=000000000041427d rbp=0000000007ff8fdf rsi=0000000000000000 rdi=0000000000000004 r8=000000000000000a r9=00000000000003f8 r10=0000000000000000 r11=0000000000000000 r12=0000000000000000 r13=0000000000000000 r14=0000000000000000 r15=0000000000000000 cr0=0000000080010031 cr2=0000000000000000 cr3=0000000007fff000 cr4=0000000000002020 cr8=0000000000000000 STACK: @402397 401102 400459 This testcase will run mwait instruction unconditional in L2 w/o check mwait cpuid. The vmlauch/vmresume emulation will merge L0's requirements and L1's requests, kvm-unit-tests doesn't set MWAIT/MONITOR EXITING bits for vmcs12. w/o commit 668fffa3f838 ("kvm: better MWAIT emulation for guests"), the MWAIT/MONITOR EXITING bits in vmcs02 will be set since it is set in vmcs01 though not in vmcs12. However, w/ the commit the bits will not be set in vmcs02 since the bits are both not set in vmcs01(if kvm_mwait_in_guest() returns true) and vmcs12. L2 should not occupy all the cpu time on L0 when L2 is idle, this patch fix it by unconditional set MWAIT/MONITOR EXTING bits against vmcs02. Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Michael S. Tsirkin Cc: Alexander Graf Cc: "Gabriel L. Somlo" Signed-off-by: Wanpeng Li --- arch/x86/kvm/vmx.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 29940b6..104a0c6 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -10098,6 +10098,13 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, exec_control &= ~CPU_BASED_USE_IO_BITMAPS; exec_control |= CPU_BASED_UNCOND_IO_EXITING; + /* + * L2 should not occupy all the cpu time on L0 when L2 + * is idle, exit every time. + */ + exec_control |= CPU_BASED_MWAIT_EXITING | + CPU_BASED_MONITOR_EXITING; + vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, exec_control); /* EXCEPTION_BITMAP and CR0_GUEST_HOST_MASK should basically be the -- 2.7.4