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From: Marcelo Tosatti <mtosatti@redhat.com>
To: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Avi Kivity <avi@redhat.com>, kvm@vger.kernel.org
Subject: Re: [PATCH] kvm: Fix kvmclock initialization on !CONFIG_KVM_GUEST
Date: Thu, 16 Aug 2012 16:57:47 -0300	[thread overview]
Message-ID: <20120816195747.GA10759@amt.cnet> (raw)
In-Reply-To: <87393o1c8q.fsf@devron.myhome.or.jp>

On Wed, Aug 15, 2012 at 11:05:57PM +0900, OGAWA Hirofumi wrote:
> 
> If !CONFIG_KVM_GUEST, kvm_smp_prepare_boot_cpu() is not defined. So,
> kvm_register_clock("primary cpu clock") in kvm_smp_prepare_boot_cpu()
> is not called.
> 
> The detail of problem is hv_clock percpu usage. hv_clock is percpu
> variable, but kvmclock_init() is called _before_ initializing percpu
> area, and doesn't update address after initialized percpu area.
> 
> So, host kvm modify the memory area _before_ initializing percpu. This
> became the cause of strange memory corruption on guest OS.
> 
> 
> This fixes it by adding kvm_smp_prepare_boot_cpu().  [we might be
> better to kill the usage before percpu initialization.]
> 
> Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

The distinction between CONFIG_KVM_CLOCK and CONFIG_KVM_GUEST is 
not so clear anymore, as this bug demonstrates.

There is no point in having a separate config option, therefore i
propose to merge the two (see other reply) instead.


  reply	other threads:[~2012-08-16 20:00 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-08-15 14:05 [PATCH] kvm: Fix kvmclock initialization on !CONFIG_KVM_GUEST OGAWA Hirofumi
2012-08-16 19:57 ` Marcelo Tosatti [this message]
2012-08-17  0:10   ` OGAWA Hirofumi
2012-08-17 17:54     ` Marcelo Tosatti
2012-08-18  0:17       ` OGAWA Hirofumi
2012-08-16 20:00 ` [PATCH] x86: KVM guest: merge CONFIG_KVM_CLOCK into CONFIG_KVM_GUEST Marcelo Tosatti

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