From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Mackerras Subject: Re: [PATCH v4 1/2] KVM: PPC: Add new capability to control MCE behaviour Date: Thu, 12 Jan 2017 20:56:28 +1100 Message-ID: <20170112095628.GA29786@fergus.ozlabs.ibm.com> References: <148396203530.1471.16105350692124392705.stgit@aravinda> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org, gleb@kernel.org, mahesh@linux.vnet.ibm.com, agraf@suse.de, kvm-ppc@vger.kernel.org, linuxppc-dev@ozlabs.org, pbonzini@redhat.com, david@gibson.dropbear.id.au To: Aravinda Prasad Return-path: Content-Disposition: inline In-Reply-To: <148396203530.1471.16105350692124392705.stgit@aravinda> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org Sender: "Linuxppc-dev" List-Id: kvm.vger.kernel.org On Mon, Jan 09, 2017 at 05:10:35PM +0530, Aravinda Prasad wrote: > This patch introduces a new KVM capability to control > how KVM behaves on machine check exception (MCE). > Without this capability, KVM redirects machine check > exceptions to guest's 0x200 vector, if the address in > error belongs to the guest. With this capability KVM > causes a guest exit with NMI exit reason. > > The new capability is required to avoid problems if > a new kernel/KVM is used with an old QEMU for guests > that don't issue "ibm,nmi-register". As old QEMU does > not understand the NMI exit type, it treats it as a > fatal error. However, the guest could have handled > the machine check error if the exception was delivered > to guest's 0x200 interrupt vector instead of NMI exit > in case of old QEMU. You need to add a description of the new capability to Documentation/virtual/kvm/api.txt. Paul.