Re: [Xen-devel] [PATCH 0/4] fix preemption handling for XENMEM_add_to_physmap_range{, _range}

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 18/12/2013 14:29, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:

> The hypervisor isn't supposed to use the input structures for
> storing continuation information - only fields explicitly used as
> hypercall outputs should ever be updated.
> 
> Obviously this implies an ABI change, but since the previous
> behavior was not intended to be that way I don't think we should
> stick to the old behavior.
> 
> There's one caveat though - with the previous model, the caller
> could - upon failure - use the updated structure to find out how
> by progress was made. However, that wasn't intended afaict,
> largely supported by this information depending on hypervisor
> internals (i.e. the caller would have to know the order of request
> processing and the meaning of the respective size fields, which
> aren't simply saying "this much was processed").
> 
> Consequently, as a follow-up we may want to consider making
> explicit (and straight forward) this progress indication on error.
> 
> 1: move XENMEM_add_to_physmap handling framework to common code
> 2: fix XENMEM_add_to_physmap preemption handling
> 3: move XENMEM_add_to_physmap_range handling framework to common code
> 4: fix XENMEM_add_to_physmap_range preemption handling
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Nice to have this fixed!

Acked-by: Keir Fraser <keir@xxxxxxx>



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