Re: [Qemu-devel] [PATCH v2] spapr: Fix RTAS token numbers

[Alexander Graf <agraf@suse.de>]

On 23.06.14 15:26, Alexey Kardashevskiy wrote:
> At the moment spapr_rtas_register() allocates a new token number for every
> new RTAS callback so numbers are not fixed and depend on the number of
> supported RTAS handlers and the exact order of spapr_rtas_register() calls.
> These tokens are copied into the device tree and remain the same during
> the guest lifetime.
>
> When we start another guest to receive a migration, it calls
> spapr_rtas_register() as well. If the number of RTAS handlers or their
> order is different in QEMU on source and destination sides, the "/rtas"
> node in the device tree will differ. Since migration overwrites the device
> tree (as it overwrites the entire RAM), the actual RTAS config on
> the destination side gets broken.
>
> This defines global contant values for every RTAS token which QEMU
> is using today.
>
> This changes spapr_rtas_register() to accept a token number instead of
> allocating one. This changes all users of spapr_rtas_register().
>
> This changes XICS-KVM not to cache tokens registered with KVM as they
> constant now.
>
> This makes TOKEN_BASE global as RTAS_XXX use TOKEN_BASE as
> a base. TOKEN_MAX is moved and renamed too and its value is changed
> to the last token + 1. Boundary checks for token values are adjusted.
>
> This reserves token numbers for "os-term" handlers and PCI hotplug
> which we are working on.
>
> Cc: Michael Roth <mdroth@linux.vnet.ibm.com>
> Cc: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Very nice. I'll apply it as soon as patchworks has it ;).


Alex