Re: [PATCH v2] x86/vpci: fix handling of BAR overlaps with non-hole regions

["Roger Pau Monné" <roger.pau@citrix.com>]

On Wed, May 21, 2025 at 10:29:26AM +0200, Jan Beulich wrote:
> On 16.05.2025 10:31, Roger Pau Monne wrote:
> > For once the message printed when a BAR overlaps with a non-hole regions is
> > not accurate on x86.  While the BAR won't be mapped by the vPCI logic, it
> > is quite likely overlapping with a reserved region in the memory map, and
> > already mapped as by default all reserved regions are identity mapped in
> > the p2m.  Fix the message so it just warns about the overlap, without
> > mentioning that the BAR won't be mapped, as this has caused confusion in
> > the past.
> 
> I was trying to get back to this, but my attempt to use this "fixed
> message" as an anchor failed: You don't modify any existing message, and
> hence I was unable to determine which other message you refer to here.
> None of the ones I looked at appear to fit this description.

OK, it's a bit tricky.  Note how the new implementation of
pci_check_bar() unconditionally returns true, which means the message
in modify_bars() will never be printed on x86.  Instead a slightly
different warning message is printed in the x86 implementation of
pci_check_bar().

That's what the above paragraph attempts to explain.

Maybe I need to adjust the last sentence so it's:

"Avoiding printing the warning message in modify_bars(), and instead
print a more lax message in the x86 implementation of pci_check_bar()
to note the current BAR position overlaps with non-hole region(s)."

Does the above make it a bit clearer?

Thanks, Roger.