Marcelo Tosatti <mtosatti@xxxxxxxxxx> writes:
> 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.
Yes, it was an another option to fix this. As note, the wrong percpu
usage (use it before initialization) is still true even if merged
KVM_CLOCK.
Thanks.
--
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
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