Re: Crash in update microcode changes - change set 18475

[Keir Fraser <keir.fraser@eu.citrix.com>]

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I¹ll take a look. Probably not hard to fix.

 -- Keir

On 15/9/08 22:34, "Ross Philipson" <Ross.Philipson@citrix.com> wrote:

> The changes for CPU microcode loading that were done recently (change set
> 18475 in unstable staging) seem to be causing a crash. I am using an Intel
> system and I get an assertion in Xen during the DOM0 boot. This is what I
> believe is going on.
>  
> In xen/arch/x86/microcode.c the routine do_microcode_update() is dispatching
> the update work to each CPU with on_each_cpu() which in turn uses an IPI to
> dispatch the callback vector on each CPU. The microcode update routine passed
> in is called in the IPI context on the target CPU (including irq_enter()
> before calling the ucode function). Within the ucode function the calls
> eventually get down to the Intel specific calls in microcode_intel.c.
> Specifically:
>  
> do_microcode_update_one()
>      microcode_update_cpu()
>             cpu_request_microcode()
>                 get_next_ucode_from_buffer()
>  
> Within the last call, vmalloc() is called and eventually _xmalloc() asserts on
> ASSERT(!in_irq()). I checked and the earlier code, though it dispatched work
> to different CPUs with IPIs, did not try to dynamically allocate memory. I am
> not sure how to fix this easily without redoing how the whole new microcode
> framework works. Also I didn¹t look closely at AMD but it may have the same
> issue. I can take a crack at fixing it but maybe someone will see a simple
> solution.
>  
> Thanks
> Ross
>  
> Ross Philipson
> Senior Software Engineer
> Citrix Systems, Inc
> 14 Crosby Drive
> Bedford, MA 01730
> 781-301-7949
> ross.philipson@citrix.com <mailto:ross.philipson@citrix.com>
>  
> 
> 
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