From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH 0/4] Avoid soft lockup message when KVM is stopped by host Date: Tue, 30 Aug 2011 09:26:30 -0300 Message-ID: <20110830122630.GA19450@amt.cnet> References: <1314660435-23293-1-git-send-email-emunson@mgebm.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: avi@redhat.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, arnd@arndb.de, riel@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, kvm-ppc@vger.kernel.org, aliguori@us.ibm.com, raharper@us.ibm.com, kvm-ia64@vger.kernel.org To: Eric B Munson Return-path: Content-Disposition: inline In-Reply-To: <1314660435-23293-1-git-send-email-emunson@mgebm.net> Sender: linux-arch-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Mon, Aug 29, 2011 at 05:27:11PM -0600, Eric B Munson wrote: > Currently, when qemu stops a guest kernel that guest will issue a soft lockup > message when it resumes. This set provides the ability for qemu to comminucate > to the guest that it has been stopped. When the guest hits the watchdog on > resume it will check if it was suspended before issuing the warning. > > Eric B Munson (4): > Add flag to indicate that a vm was stopped by the host > Add functions to check if the host has stopped the vm > Add generic stubs for kvm stop check functions > Add check for suspended vm in softlockup detector > > arch/x86/include/asm/pvclock-abi.h | 1 + > arch/x86/include/asm/pvclock.h | 2 ++ > arch/x86/kernel/kvmclock.c | 14 ++++++++++++++ > include/asm-generic/pvclock.h | 14 ++++++++++++++ > kernel/watchdog.c | 12 ++++++++++++ > 5 files changed, 43 insertions(+), 0 deletions(-) > create mode 100644 include/asm-generic/pvclock.h > > -- > 1.7.4.1 How is the host supposed to set this flag? As mentioned previously, if you save save/restore the offset added to kvmclock on stop/cont (and the TSC MSR, forgot to mention that), no paravirt infrastructure is required. Which means the issue is also fixed for older guests.