From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [PATCH] KVM: VMX: Preserve host CR4.MCE value while in guest mode. Date: Fri, 17 Apr 2015 10:55:39 +0200 Message-ID: <20150417085539.GA22515@kroah.com> References: <1429210685-19510-1-git-send-email-serebrin@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org, stable@vger.kernel.org, luto@amacapital.net, pbonzini@redhat.com, jankiszka@siemens.com To: Ben Serebrin Return-path: Content-Disposition: inline In-Reply-To: <1429210685-19510-1-git-send-email-serebrin@google.com> Sender: stable-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Thu, Apr 16, 2015 at 11:58:05AM -0700, Ben Serebrin wrote: > The host's decision to enable machine check exceptions should remain > in force during non-root mode. KVM was writing 0 to cr4 on VCPU reset > and passed a slightly-modified 0 to the vmcs.guest_cr4 value. > > Tested: Built. > On earlier version, tested by injecting machine check > while a guest is spinning. > > Before the change, if guest CR4.MCE==0, then the machine check is > escalated to Catastrophic Error (CATERR) and the machine dies. > If guest CR4.MCE==1, then the machine check causes VMEXIT and is > handled normally by host Linux. After the change, injecting a machine > check causes normal Linux machine check handling. > > Signed-off-by: Ben Serebrin > --- > arch/x86/kvm/vmx.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read Documentation/stable_kernel_rules.txt for how to do this properly.