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

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Mar 04, 2026 at 10:39:56AM -0500, Stewart Hildebrand wrote:
> 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.

Sure, please keep the RB.

Thanks, Roger.