From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx2.redhat.com ([66.187.237.31]) by bombadil.infradead.org with esmtp (Exim 4.68 #1 (Red Hat Linux)) id 1KxmWt-0005TI-4O for kexec@lists.infradead.org; Wed, 05 Nov 2008 17:50:55 +0000 Date: Wed, 5 Nov 2008 15:50:05 -0200 From: Eduardo Habkost Subject: Re: [PATCH 15/16] kvm: x86: set kdump virt_disable function on initialization Message-ID: <20081105175004.GI5247@blackpad> References: <1225810364-8990-1-git-send-email-ehabkost@redhat.com> <1225810364-8990-16-git-send-email-ehabkost@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: "Eric W. Biederman" Cc: Andrew Morton , kvm@vger.kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , Haren Myneni , Simon Horman , Avi Kivity , Ingo Molnar , Andrey Borzenkov , mingo@redhat.com, Vivek Goyal On Wed, Nov 05, 2008 at 09:26:53AM -0800, Eric W. Biederman wrote: > Eduardo Habkost writes: > > > Finally implement the virt_disable function for kdump. It will call > > kvm_x86_ops->crash_hardware_disable(), that will disable virtualization > > extensions on the CPU if it is not disabled yet. > > > > Signed-off-by: Eduardo Habkost > > --- > > arch/x86/kvm/x86.c | 19 ++++++++++++++++++- > > 1 files changed, 18 insertions(+), 1 deletions(-) > > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index 049c6a0..9e61baf 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -40,6 +40,7 @@ > > #include > > #include > > #include > > +#include > > > > #define MAX_IO_MSRS 256 > > #define CR0_RESERVED_BITS \ > > @@ -2581,6 +2582,13 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct > > kvm_run *run, int in, > > } > > EXPORT_SYMBOL_GPL(kvm_emulate_pio_string); > > > > +/* Called at crash time, so we can disable virtualization if needed > > + */ > > +static void crash_hardware_disable(void) > > +{ > > + kvm_x86_ops->crash_hardware_disable(NULL); > > +} > > + > > int kvm_arch_init(void *opaque) > > { > > int r; > > @@ -2605,9 +2613,15 @@ int kvm_arch_init(void *opaque) > > > > kvm_x86_ops = ops; > > > > + r = set_virt_disable_func(crash_hardware_disable); > > Can we make this say: > set_virt_disable_func(kvm_x86_ops->crash_hardware_disable); > > So we can avoid going through 2 levels of function pointers? > I find that a little scary in code that might be running > at the edge of stack overflow. When I've checked this (on x86_64), gcc did tail recursion optimization and the call was just a jump to the function, so stack usage shouldn't be a problem. But I am inclined to agree with you about the excess of abstraction. -- Eduardo _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756117AbYKERwD (ORCPT ); Wed, 5 Nov 2008 12:52:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752708AbYKERvv (ORCPT ); Wed, 5 Nov 2008 12:51:51 -0500 Received: from mx2.redhat.com ([66.187.237.31]:43701 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752434AbYKERvu (ORCPT ); Wed, 5 Nov 2008 12:51:50 -0500 Date: Wed, 5 Nov 2008 15:50:05 -0200 From: Eduardo Habkost To: "Eric W. Biederman" Cc: Avi Kivity , Ingo Molnar , Simon Horman , Andrew Morton , Vivek Goyal , Haren Myneni , Andrey Borzenkov , mingo@redhat.com, "Rafael J. Wysocki" , kexec@lists.infradead.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 15/16] kvm: x86: set kdump virt_disable function on initialization Message-ID: <20081105175004.GI5247@blackpad> References: <1225810364-8990-1-git-send-email-ehabkost@redhat.com> <1225810364-8990-16-git-send-email-ehabkost@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Fnord: you can see the fnord User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 05, 2008 at 09:26:53AM -0800, Eric W. Biederman wrote: > Eduardo Habkost writes: > > > Finally implement the virt_disable function for kdump. It will call > > kvm_x86_ops->crash_hardware_disable(), that will disable virtualization > > extensions on the CPU if it is not disabled yet. > > > > Signed-off-by: Eduardo Habkost > > --- > > arch/x86/kvm/x86.c | 19 ++++++++++++++++++- > > 1 files changed, 18 insertions(+), 1 deletions(-) > > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index 049c6a0..9e61baf 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -40,6 +40,7 @@ > > #include > > #include > > #include > > +#include > > > > #define MAX_IO_MSRS 256 > > #define CR0_RESERVED_BITS \ > > @@ -2581,6 +2582,13 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct > > kvm_run *run, int in, > > } > > EXPORT_SYMBOL_GPL(kvm_emulate_pio_string); > > > > +/* Called at crash time, so we can disable virtualization if needed > > + */ > > +static void crash_hardware_disable(void) > > +{ > > + kvm_x86_ops->crash_hardware_disable(NULL); > > +} > > + > > int kvm_arch_init(void *opaque) > > { > > int r; > > @@ -2605,9 +2613,15 @@ int kvm_arch_init(void *opaque) > > > > kvm_x86_ops = ops; > > > > + r = set_virt_disable_func(crash_hardware_disable); > > Can we make this say: > set_virt_disable_func(kvm_x86_ops->crash_hardware_disable); > > So we can avoid going through 2 levels of function pointers? > I find that a little scary in code that might be running > at the edge of stack overflow. When I've checked this (on x86_64), gcc did tail recursion optimization and the call was just a jump to the function, so stack usage shouldn't be a problem. But I am inclined to agree with you about the excess of abstraction. -- Eduardo From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eduardo Habkost Subject: Re: [PATCH 15/16] kvm: x86: set kdump virt_disable function on initialization Date: Wed, 5 Nov 2008 15:50:05 -0200 Message-ID: <20081105175004.GI5247@blackpad> References: <1225810364-8990-1-git-send-email-ehabkost@redhat.com> <1225810364-8990-16-git-send-email-ehabkost@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Andrew Morton , kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "Rafael J. Wysocki" , Haren Myneni , Simon Horman , Avi Kivity , Ingo Molnar , Andrey Borzenkov , mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, Vivek Goyal To: "Eric W. Biederman" Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kexec-bounces-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Errors-To: kexec-bounces+glkk-kexec=m.gmane.org-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: kvm.vger.kernel.org On Wed, Nov 05, 2008 at 09:26:53AM -0800, Eric W. Biederman wrote: > Eduardo Habkost writes: > > > Finally implement the virt_disable function for kdump. It will call > > kvm_x86_ops->crash_hardware_disable(), that will disable virtualization > > extensions on the CPU if it is not disabled yet. > > > > Signed-off-by: Eduardo Habkost > > --- > > arch/x86/kvm/x86.c | 19 ++++++++++++++++++- > > 1 files changed, 18 insertions(+), 1 deletions(-) > > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index 049c6a0..9e61baf 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -40,6 +40,7 @@ > > #include > > #include > > #include > > +#include > > > > #define MAX_IO_MSRS 256 > > #define CR0_RESERVED_BITS \ > > @@ -2581,6 +2582,13 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct > > kvm_run *run, int in, > > } > > EXPORT_SYMBOL_GPL(kvm_emulate_pio_string); > > > > +/* Called at crash time, so we can disable virtualization if needed > > + */ > > +static void crash_hardware_disable(void) > > +{ > > + kvm_x86_ops->crash_hardware_disable(NULL); > > +} > > + > > int kvm_arch_init(void *opaque) > > { > > int r; > > @@ -2605,9 +2613,15 @@ int kvm_arch_init(void *opaque) > > > > kvm_x86_ops = ops; > > > > + r = set_virt_disable_func(crash_hardware_disable); > > Can we make this say: > set_virt_disable_func(kvm_x86_ops->crash_hardware_disable); > > So we can avoid going through 2 levels of function pointers? > I find that a little scary in code that might be running > at the edge of stack overflow. When I've checked this (on x86_64), gcc did tail recursion optimization and the call was just a jump to the function, so stack usage shouldn't be a problem. But I am inclined to agree with you about the excess of abstraction. -- Eduardo