From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH 0/4 V13] Avoid soft lockup message when KVM is stopped by host Date: Mon, 5 Mar 2012 13:39:43 -0300 Message-ID: <20120305163943.GA10338@amt.cnet> References: <1328713666-11424-1-git-send-email-emunson@mgebm.net> <20120214152931.GA6881@mgebm.net> <20120214153836.GA21106@amt.cnet> <20120214155013.GB6881@mgebm.net> <20120214161009.GA21515@amt.cnet> <20120214211720.GC6881@mgebm.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120214211720.GC6881@mgebm.net> Sender: linux-kernel-owner@vger.kernel.org To: Eric B Munson Cc: avi@redhat.com, mingo@redhat.com, hpa@zytor.com, ryanh@linux.vnet.ibm.com, aliguori@us.ibm.com, kvm@vger.kernel.org, linux-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org List-Id: linux-arch.vger.kernel.org On Tue, Feb 14, 2012 at 04:17:20PM -0500, Eric B Munson wrote: > On Tue, 14 Feb 2012, Marcelo Tosatti wrote: > > > On Tue, Feb 14, 2012 at 10:50:13AM -0500, Eric B Munson wrote: > > > On Tue, 14 Feb 2012, Marcelo Tosatti wrote: > > > > > > > On Tue, Feb 14, 2012 at 10:29:31AM -0500, Eric B Munson wrote: > > > > > On Wed, 08 Feb 2012, Eric B Munson wrote: > > > > > > > > > > > > > > > > > When a guest kernel is stopped by the host hypervisor it can look like a soft > > > > > > lockup to the guest kernel. This false warning can mask later soft lockup > > > > > > warnings which may be real. This patch series adds a method for a host > > > > > > hypervisor to communicate to a guest kernel that it is being stopped. The > > > > > > final patch in the series has the watchdog check this flag when it goes to > > > > > > issue a soft lockup warning and skip the warning if the guest knows it was > > > > > > stopped. > > > > > > > > > > > > It was attempted to solve this in Qemu, but the side effects of saving and > > > > > > restoring the clock and tsc for each vcpu put the wall clock of the guest behind > > > > > > by the amount of time of the pause. This forces a guest to have ntp running > > > > > > in order to keep the wall clock accurate. > > > > > > > > > > Avi, > > > > > > > > > > Is this set fit for merging or is there something else you want changed? > > > > > > > > Eric, > > > > > > > > On Message-ID: <20120210160536.GA23363@amt.cnet>, i asked: > > > > > > > > How is the stub getting included for other architectures again? > > > > > > > > > > Marcelo, > > > > > > Sorry, I put out V13 to answer that. There is a stub in asm-generic that was > > > lost in the V11-V12 rebase. This stub has be included in the V13 set. > > > > > > Eric > > > > Eric, > > > > I know the stub has been included in the series. But i am asking how > > it is #include'ed for other architectures? (can't see that). > > Marcelo, > > kernel/watchdog.c now includes linux/kvm_para.h which includes asm/kvm_para.h. > The check_and_clear function is defined in arch include/asm/kvm_para.h or in > asm-generic/kvm_para.h for any arch lacking the specific header in their asm > include dir. If I have misunderstood how these headers work, please let me > know and I will fix it. There is no automatic inclusion of asm-generic/ headers. You must create kvm_para.h in each architecture's include/asm/ directory, #including asm-generic/kvm_para.h. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:53912 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752440Ab2CEQm2 (ORCPT ); Mon, 5 Mar 2012 11:42:28 -0500 Date: Mon, 5 Mar 2012 13:39:43 -0300 From: Marcelo Tosatti Subject: Re: [PATCH 0/4 V13] Avoid soft lockup message when KVM is stopped by host Message-ID: <20120305163943.GA10338@amt.cnet> References: <1328713666-11424-1-git-send-email-emunson@mgebm.net> <20120214152931.GA6881@mgebm.net> <20120214153836.GA21106@amt.cnet> <20120214155013.GB6881@mgebm.net> <20120214161009.GA21515@amt.cnet> <20120214211720.GC6881@mgebm.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120214211720.GC6881@mgebm.net> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Eric B Munson Cc: avi@redhat.com, mingo@redhat.com, hpa@zytor.com, ryanh@linux.vnet.ibm.com, aliguori@us.ibm.com, kvm@vger.kernel.org, linux-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org Message-ID: <20120305163943.H25fE3szfrtzgeQ_LW-dtpmpbmPQ2B-EC-NDbK5zeq0@z> On Tue, Feb 14, 2012 at 04:17:20PM -0500, Eric B Munson wrote: > On Tue, 14 Feb 2012, Marcelo Tosatti wrote: > > > On Tue, Feb 14, 2012 at 10:50:13AM -0500, Eric B Munson wrote: > > > On Tue, 14 Feb 2012, Marcelo Tosatti wrote: > > > > > > > On Tue, Feb 14, 2012 at 10:29:31AM -0500, Eric B Munson wrote: > > > > > On Wed, 08 Feb 2012, Eric B Munson wrote: > > > > > > > > > > > > > > > > > When a guest kernel is stopped by the host hypervisor it can look like a soft > > > > > > lockup to the guest kernel. This false warning can mask later soft lockup > > > > > > warnings which may be real. This patch series adds a method for a host > > > > > > hypervisor to communicate to a guest kernel that it is being stopped. The > > > > > > final patch in the series has the watchdog check this flag when it goes to > > > > > > issue a soft lockup warning and skip the warning if the guest knows it was > > > > > > stopped. > > > > > > > > > > > > It was attempted to solve this in Qemu, but the side effects of saving and > > > > > > restoring the clock and tsc for each vcpu put the wall clock of the guest behind > > > > > > by the amount of time of the pause. This forces a guest to have ntp running > > > > > > in order to keep the wall clock accurate. > > > > > > > > > > Avi, > > > > > > > > > > Is this set fit for merging or is there something else you want changed? > > > > > > > > Eric, > > > > > > > > On Message-ID: <20120210160536.GA23363@amt.cnet>, i asked: > > > > > > > > How is the stub getting included for other architectures again? > > > > > > > > > > Marcelo, > > > > > > Sorry, I put out V13 to answer that. There is a stub in asm-generic that was > > > lost in the V11-V12 rebase. This stub has be included in the V13 set. > > > > > > Eric > > > > Eric, > > > > I know the stub has been included in the series. But i am asking how > > it is #include'ed for other architectures? (can't see that). > > Marcelo, > > kernel/watchdog.c now includes linux/kvm_para.h which includes asm/kvm_para.h. > The check_and_clear function is defined in arch include/asm/kvm_para.h or in > asm-generic/kvm_para.h for any arch lacking the specific header in their asm > include dir. If I have misunderstood how these headers work, please let me > know and I will fix it. There is no automatic inclusion of asm-generic/ headers. You must create kvm_para.h in each architecture's include/asm/ directory, #including asm-generic/kvm_para.h.