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@xxxxxxxxxxxxxxxxxx>
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.
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