Re: [Xen-devel] [PATCH 2/2] x86/microcode: enable boot time (pre-Dom0) loading

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 30.11.11 at 10:05, Keir Fraser <keir.xen@xxxxxxxxx> wrote:
> On 30/11/2011 16:27, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> 
>> 
>> In order to not convert the spin_lock() in microcode_update_cpu() (and
>> then obviously also all other uses on microcode_mutex) to
>> spin_lock_irqsave() (which would be undesirable for the hypercall
>> context in which the function also runs), the boot time handling gets
>> done using a tasklet (instead of using on_selected_cpus()).
> 
> Can you explain this some more? Why would the conversion to
> spin_lock_irqsave be required when spin_lock is sufficient for current usage
> from dom0 hypercall?

Because check_lock() wants locks to be acquired consistently?

Jan


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