Re: [Xen-devel] [PATCH] C6 state with EOI issue fix for some Intel processors

[Sheng Yang <sheng@xxxxxxxxxxxxxxx>]

On Wednesday 15 September 2010 15:10:43 Sheng Yang wrote:
> There is an errata in some of Intel processors.
> 
> AAJ72. EOI Transaction May Not be Sent if Software Enters Core C6 During
> an Interrupt Service Routine
> 
> If core C6 is entered after the start of an interrupt service routine but
> before a write to the APIC EOI register, the core may not send an EOI
> transaction (if needed) and further interrupts from the same priority
> level or lower may be blocked.
> 
> This patch fix this issue, by checking if ISR is pending before enter deep
> Cx state. If so, it would use power->safe_state instead of deep Cx state
> to prevent the above issue happen.

Signed-off-by: Sheng Yang <sheng@xxxxxxxxxxxxxxx>

--
regards
Yang, Sheng

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