Re: [PATCH v3 1/3] hw/xen/xen_pt: Save back data only for declared registers

[Anthony PERARD <anthony.perard@vates.tech>]

On Mon, May 06, 2024 at 02:33:20AM +0200, Marek Marczykowski-Górecki wrote:
> Call pci_default_write_config() only after resolving any handlers from
> XenPTRegInfo structures, and only with a value updated with those
> handlers. This is important for two reasons:
> 1. XenPTRegInfo has ro_mask which needs to be enforced - Xen-specific
>    hooks do that on their own (especially xen_pt_*_reg_write()).
> 2. Not setting value early allows hooks to see the old value too.
>
> If it would be only about the first point, setting PCIDevice.wmask would
> probably be sufficient, but given the second point, change those
> writes.
>
> Relevant handlers already save data back to the emulated registers
> space, call the pci_default_write_config() only for its side effects.
>
> Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
> ---
> v3:
>  - use emulated register value for pci_default_write_config() call, not
>    the one for writting back to the hardware
>  - greatly simplify the patch by calling pci_default_write_config() on
>    the whole value
> v2:
>  - rewrite commit message, previous one was very misleading
>  - fix loop saving register values
>  - fix int overflow when calculating write mask

Reviewed-by: Anthony PERARD <anthony.perard@vates.tech>

Thanks,

--

Anthony Perard | Vates XCP-ng Developer

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