On 01/27/2010 08:54 AM, Jan Kiszka wrote:
This patch originates in the mp_state writeback issue: During runtime
and even on reset, we must not write the previously saved VCPU state
back into the kernel in an uncontrolled fashion. E.g mp_state should
only written on reset or on VCPU setup. Certain clocks (e.g. the TSC)
may only be written on setup or after vmload.
By introducing additional information about the context of the planned
vcpu state manipulation, we can simply skip sensitive states like
mp_state when updating the in-kernel state. The planned modifications
are defined when calling cpu_synchronize_state. They accumulate, ie.
once a full writeback was requested, it will stick until it was
performed.
This patch already fixes existing writeback issues in upstream KVM by
only selectively writing MSR_IA32_TSC, MSR_KVM_SYSTEM_TIME,
MSR_KVM_WALL_CLOCK, the mp_state and the vcpu_events.
Signed-off-by: Jan Kiszka<jan.kis...@siemens.com>
I think the context argument makes the function very difficult to call
correctly.
I'd suggest making CPU_MODIFY_RUNTIME the behaviour of
cpu_synchronize_state. I'd suggest adding another function to handle
init like cpu_init_state(). Likewise, if an explicit reset state is
needed, I think a cpu_init_state_after_reset() makes sense.
I don't quite understand the context that NONE should be used in.
I think the key point though is to handle RUNTIME mostly transparently
since it's the most common case.
Regards,
Anthony Liguori
