From: Avi Kivity <avi@redhat.com>
To: Eduardo Habkost <ehabkost@redhat.com>
Cc: Andrew Morton <akpm@osdl.org>,
kvm@vger.kernel.org, kexec@lists.infradead.org,
Haren Myneni <hbabu@us.ibm.com>,
Simon Horman <horms@verge.net.au>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH 1/6] kdump: crash-time virt disable function
Date: Thu, 30 Oct 2008 15:50:31 +0200 [thread overview]
Message-ID: <4909BBA7.1020307@redhat.com> (raw)
In-Reply-To: <1225373687-6960-2-git-send-email-ehabkost@redhat.com>
Eduardo Habkost wrote:
> This patch adds an interface to set a function to be called on crash time,
> on each CPU. The function will be set by code that enables virtualization
> extensions on the CPUs (i.e. KVM). It will be called once on each CPU
> by machine_crash_shutdown(), and should do the very least to disable
> virt extensions on the CPU where it is being called.
>
> The function will be used by KVM to disable virtualization before halting
> the CPUs, otherwise the booting of the kdump kernel may hang. It does
> hang, when vmx is enabled, and I wouldn't be surprised if having svm
> enabled also causes problems.
>
> The functions that set the function pointer uses RCU synchronization,
> just in case the crash NMI is triggered while KVM is unloading.
>
> We can't just use the same notifiers used at reboot time (that are used
> by non-crash-dump kexec), because at crash time some CPUs may have IRQs
> disabled, so we can't use IPIs. The crash shutdown code use NMIs to
> tell the other CPUs to be halted, so the notifier call is hooked into
> the CPU halting code that is on the crash shutdown NMI handler.
>
> +static void (*virt_disable_fn)(unsigned int cpu);
>
Since you never use the cpu argument, I suggest dropping it.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Eduardo Habkost <ehabkost-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Andrew Morton <akpm-3NddpPZAyC0@public.gmane.org>,
kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
Haren Myneni <hbabu-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>,
Simon Horman <horms-/R6kz+dDXgpPR4JQBCEnsQ@public.gmane.org>,
"Eric W. Biederman"
<ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>,
Vivek Goyal <vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH 1/6] kdump: crash-time virt disable function
Date: Thu, 30 Oct 2008 15:50:31 +0200 [thread overview]
Message-ID: <4909BBA7.1020307@redhat.com> (raw)
In-Reply-To: <1225373687-6960-2-git-send-email-ehabkost-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Eduardo Habkost wrote:
> This patch adds an interface to set a function to be called on crash time,
> on each CPU. The function will be set by code that enables virtualization
> extensions on the CPUs (i.e. KVM). It will be called once on each CPU
> by machine_crash_shutdown(), and should do the very least to disable
> virt extensions on the CPU where it is being called.
>
> The function will be used by KVM to disable virtualization before halting
> the CPUs, otherwise the booting of the kdump kernel may hang. It does
> hang, when vmx is enabled, and I wouldn't be surprised if having svm
> enabled also causes problems.
>
> The functions that set the function pointer uses RCU synchronization,
> just in case the crash NMI is triggered while KVM is unloading.
>
> We can't just use the same notifiers used at reboot time (that are used
> by non-crash-dump kexec), because at crash time some CPUs may have IRQs
> disabled, so we can't use IPIs. The crash shutdown code use NMIs to
> tell the other CPUs to be halted, so the notifier call is hooked into
> the CPU halting code that is on the crash shutdown NMI handler.
>
> +static void (*virt_disable_fn)(unsigned int cpu);
>
Since you never use the cpu argument, I suggest dropping it.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2008-10-30 13:50 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-30 13:34 [PATCH 0/6] kdump: disable virtualization extensions on crash (v2) Eduardo Habkost
2008-10-30 13:34 ` Eduardo Habkost
2008-10-30 13:34 ` [PATCH 1/6] kdump: crash-time virt disable function Eduardo Habkost
2008-10-30 13:34 ` Eduardo Habkost
2008-10-30 13:50 ` Avi Kivity [this message]
2008-10-30 13:50 ` Avi Kivity
2008-10-30 16:24 ` Eduardo Habkost
2008-10-30 16:24 ` Eduardo Habkost
2008-10-30 13:34 ` [PATCH 2/6] kvm_x86_ops: crash_hardware_disable() operation Eduardo Habkost
2008-10-30 13:34 ` Eduardo Habkost
2008-10-30 13:34 ` [PATCH 3/6] kvm: svm: set crash_hardware_disable to svm_hardware_disable Eduardo Habkost
2008-10-30 13:34 ` Eduardo Habkost
2008-10-30 13:34 ` [PATCH 4/6] kvm: vmx: crash_hardware_disable function Eduardo Habkost
2008-10-30 13:34 ` Eduardo Habkost
2008-10-30 13:34 ` [PATCH 5/6] kvmx: x86: set kvm_x86_ops earlier on kvm_arch_init() Eduardo Habkost
2008-10-30 13:34 ` Eduardo Habkost
2008-10-30 13:34 ` [PATCH 6/6] kvm: x86: set kdump virt_disable function on initialization Eduardo Habkost
2008-10-30 13:34 ` Eduardo Habkost
2008-10-30 13:52 ` [PATCH 0/6] kdump: disable virtualization extensions on crash (v2) Avi Kivity
2008-10-30 13:52 ` Avi Kivity
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