From: Avi Kivity <avi@redhat.com>
To: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: x86@kernel.org, "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
linux-doc@vger.kernel.org, mtosatti@redhat.com,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/3] x86: clear vmcss on all cpus when doing kdump if necessary
Date: Mon, 15 Oct 2012 17:43:20 +0200 [thread overview]
Message-ID: <507C2F18.8080904@redhat.com> (raw)
In-Reply-To: <5077BB7B.4030203@cn.fujitsu.com>
On 10/12/2012 08:40 AM, Zhang Yanfei wrote:
> Currently, kdump just makes all the logical processors leave VMX operation by
> executing VMXOFF instruction, so any VMCSs active on the logical processors may
> be corrupted. But, sometimes, we need the VMCSs to debug guest images contained
> in the host vmcore. To prevent the corruption, we should VMCLEAR the VMCSs before
> executing the VMXOFF instruction.
How have you verified that VMXOFF doesn't flush cached VMCSs already?
>
> The patch set provides an alternative way to clear VMCSs related to guests
> on all cpus when host is doing kdump.
>
I'm not sure the sysctl is really necessary. The only reason to turn if
off is if the corruption is so severe that the loaded vmcs list itself
causes a crash. I think it should be rare enough that we can do it
unconditionally.
--
error compiling committee.c: too many arguments to function
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WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Zhang Yanfei <zhangyanfei-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
Cc: x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
"kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
mtosatti-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 0/3] x86: clear vmcss on all cpus when doing kdump if necessary
Date: Mon, 15 Oct 2012 17:43:20 +0200 [thread overview]
Message-ID: <507C2F18.8080904@redhat.com> (raw)
In-Reply-To: <5077BB7B.4030203-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
On 10/12/2012 08:40 AM, Zhang Yanfei wrote:
> Currently, kdump just makes all the logical processors leave VMX operation by
> executing VMXOFF instruction, so any VMCSs active on the logical processors may
> be corrupted. But, sometimes, we need the VMCSs to debug guest images contained
> in the host vmcore. To prevent the corruption, we should VMCLEAR the VMCSs before
> executing the VMXOFF instruction.
How have you verified that VMXOFF doesn't flush cached VMCSs already?
>
> The patch set provides an alternative way to clear VMCSs related to guests
> on all cpus when host is doing kdump.
>
I'm not sure the sysctl is really necessary. The only reason to turn if
off is if the corruption is so severe that the loaded vmcs list itself
causes a crash. I think it should be rare enough that we can do it
unconditionally.
--
error compiling committee.c: too many arguments to function
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@redhat.com>
To: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: x86@kernel.org, kexec@lists.infradead.org,
linux-doc@vger.kernel.org, mtosatti@redhat.com,
linux-kernel@vger.kernel.org,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH 0/3] x86: clear vmcss on all cpus when doing kdump if necessary
Date: Mon, 15 Oct 2012 17:43:20 +0200 [thread overview]
Message-ID: <507C2F18.8080904@redhat.com> (raw)
In-Reply-To: <5077BB7B.4030203@cn.fujitsu.com>
On 10/12/2012 08:40 AM, Zhang Yanfei wrote:
> Currently, kdump just makes all the logical processors leave VMX operation by
> executing VMXOFF instruction, so any VMCSs active on the logical processors may
> be corrupted. But, sometimes, we need the VMCSs to debug guest images contained
> in the host vmcore. To prevent the corruption, we should VMCLEAR the VMCSs before
> executing the VMXOFF instruction.
How have you verified that VMXOFF doesn't flush cached VMCSs already?
>
> The patch set provides an alternative way to clear VMCSs related to guests
> on all cpus when host is doing kdump.
>
I'm not sure the sysctl is really necessary. The only reason to turn if
off is if the corruption is so severe that the loaded vmcs list itself
causes a crash. I think it should be rare enough that we can do it
unconditionally.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2012-10-15 15:43 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-12 6:40 [PATCH 0/3] x86: clear vmcss on all cpus when doing kdump if necessary Zhang Yanfei
2012-10-12 6:40 ` Zhang Yanfei
2012-10-12 6:43 ` [PATCH 1/3] x86/kexec: clear vmcss on all cpus " Zhang Yanfei
2012-10-12 6:43 ` Zhang Yanfei
2012-10-12 6:44 ` [PATCH 2/3] KVM: make crash_clear_loaded_vmcss valid when kvm_intel is loaded Zhang Yanfei
2012-10-12 6:44 ` Zhang Yanfei
2012-10-12 6:45 ` [PATCH 3/3] sysctl: introduce a new interface to control kdump-vmcs-clear behaviour Zhang Yanfei
2012-10-12 6:45 ` Zhang Yanfei
2012-10-15 15:43 ` Avi Kivity [this message]
2012-10-15 15:43 ` [PATCH 0/3] x86: clear vmcss on all cpus when doing kdump if necessary Avi Kivity
2012-10-15 15:43 ` Avi Kivity
2012-10-17 2:28 ` Zhang Yanfei
2012-10-17 2:28 ` Zhang Yanfei
2012-10-17 10:16 ` Avi Kivity
2012-10-17 10:16 ` Avi Kivity
2012-10-18 1:12 ` Zhang Yanfei
2012-10-18 1:12 ` Zhang Yanfei
2012-10-18 10:55 ` Avi Kivity
2012-10-18 10:55 ` Avi Kivity
2012-10-19 4:51 ` Zhang Yanfei
2012-10-19 4:51 ` Zhang Yanfei
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