Re: [Xen-ia64-devel] EFI Mapping Windows Install Crash Bug

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

On Thu, Jul 03, 2008 at 08:50:56PM +1000, Simon Horman wrote:
> Hi,
> 
> I have been looking over the SAL manual and looking into where
> exactly the lockup that I am seeing occurs.
> 
> What seems to happen is this.
> 
> If ia64_mca_cpe_int_caller() is called from vmx context (is that the
> right word?) then when it calls ia64_log_queue() which in turn calls
> ia64_sal_get_state_info() then as the SAL_GET_STATE_INFO call is being
> made (I'm pretty sure that it is inside the firmware)
> ia64_mca_ucmc_handler() is invoked. I presume that this is because an
> unrecoverable machine check occurs during the SAL_GET_STATE_INFO call.
> 
> The call to ia64_mca_ucmc_handler() seems to complete successfully
> (including a call to ia64_sal_get_state_info() via ia64_log_queue()).
> Just after that the hypervisor locks up, presumably because execution
> goes back to the original SAL_GET_STATE_INFO call that caused the
> unrecoverable machine check.
> 
> With regards to rr7. It is not set to EFI RR when entering
> ia64_mca_cpe_int_caller(), but it is when entering
> ia64_mca_ucmc_handler(), which makes sense, as it should be set when
> going into the first SAL_GET_STATE_INFO call.

That's great.
Table 9-2 SAL spec says that SAL_GET_STATE_INFO is NOT reentrant,
the above explains why the hypervisor locks up.

> My latest micro-hack involves having ia64_sal_get_state_info() return 0,
> without going into SAL, if VMX_DOMAIN(current) is true, which seems to
> work.
> 
> I will ponder the SAL manual some more to try and work out why
> EFI RR + VMX (+ IRQ?) + SAL_GET_STATE_INFO -> bad

Yes, now the next question is why the mca occurs and
whether it can/should be avoided.

Is it possible to determine what mca occurs?
The mca record might be in nvram, if so there should be a way
to retrieve them.
-- 
yamahata

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