Re: [Xen-devel] [PATCH v2] x86/PV: fix unintended dependency of m2p-strict mode on migration-v2

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 02/02/16 15:14, Jan Beulich wrote:
> This went unnoticed until a backport of this to an older Xen got used,
> causing migration of guests enabling this VM assist to fail, because
> page table pinning there precedes vCPU context loading, and hence L4
> tables get initialized for the wrong mode. Fix this by post-processing
> L4 tables when setting the intended VM assist flags for the guest.
>
> Note that this leaves in place a dependency on vCPU 0 getting its guest
> context restored first, but afaict the logic here is not the only thing
> depending on that.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> v2: Avoid entering the loop when strict mode was already before, which
>     in turn requires deferring the assignment to d->vm_assist until
>     after the loop.

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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