Re: [PATCH v3] vpci/msix: check for BARs enabled in vpci_make_msix_hole

[Stewart Hildebrand <stewart.hildebrand@xxxxxxx>]

On 3/4/26 10:23, Roger Pau Monné wrote:
> On Wed, Feb 25, 2026 at 09:57:38PM -0500, Stewart Hildebrand wrote:
>> A hotplugged PCI device may be added uninitialized. In particular,
>> memory decoding might be disabled and the BARs might be zeroed. In this
>> case, the BARs will not be mapped in p2m. However, vpci_make_msix_hole()
>> unconditionally attempts to punch holes in p2m, leading to init_msix()
>> failing:
>>
>> (XEN) d0v0 0000:01:00.0: existing mapping (mfn: 1c1880 type: 0) at 0 
>> clobbers MSIX MMIO area
>> (XEN) d0 0000:01:00.0: init legacy cap 17 fail rc=-17, mask it
>>
>> vpci_make_msix_hole() should only attempt to punch holes if the BARs
>> containing the MSI-X/PBA tables are mapped in p2m. Introduce a helper
>> for checking if a BAR is enabled, and add a check for the situation
>> inside vpci_make_msix_hole().
>>
>> As a result of the newly introduced checks in vpci_make_msix_hole(),
>> move the call to vpci_make_msix_hole() within modify_decoding() to after
>> setting ->enabled.
>>
>> Fixes: ee2eb6849d50 ("vpci: Refactor REGISTER_VPCI_INIT")
>> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
> 
> Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> 
> Thanks.

Thanks!

I would like to point out that this now needs a rebase:
The helper vmsix_table_bar_valid() should be moved to the new private.h.
I'd be happy to send v4, assuming I can retain your R-b.