Re: [XEN PATCH v5] hvmloader: Enable MMIO and I/O decode, after all resource allocation

["Shamsundara Havanur, Harsha" <havanur@xxxxxxxxxx>]

On Wed, 2020-04-15 at 16:14 +0200, Jan Beulich wrote:
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> 
> On 15.04.2020 14:27, Harsha Shamsundara Havanur wrote:
> > It was observed that PCI MMIO and/or IO BARs were programmed with
> > memory and I/O decodes (bits 0 and 1 of PCI COMMAND register)
> > enabled,
> > during PCI setup phase. This resulted in incorrect memory mapping
> > as
> > soon as the lower half of the 64 bit bar is programmed.
> > This displaced any RAM mappings under 4G. After the
> > upper half is programmed PCI memory mapping is restored to its
> > intended high mem location, but the RAM displaced is not restored.
> > The OS then continues to boot and function until it tries to access
> > the displaced RAM at which point it suffers a page fault and
> > crashes.
> > 
> > This patch address the issue by deferring enablement of memory and
> > I/O decode in command register until all the resources, like
> > interrupts
> > I/O and/or MMIO BARs for all the PCI device functions are
> > programmed,
> > in the descending order of memory requested.
> > 
> > Signed-off-by: Harsha Shamsundara Havanur <havanur@xxxxxxxxxx>
> 
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> with one further adjustment:
> 
> > @@ -120,6 +121,13 @@ void pci_setup(void)
> >       */
> >      bool allow_memory_relocate = 1;
> > 
> > +    BUILD_BUG_ON((typeof(*pci_devfn_decode_type))PCI_COMMAND_IO !=
> > +            PCI_COMMAND_IO);
> > +    BUILD_BUG_ON((typeof(*pci_devfn_decode_type))PCI_COMMAND_MEMOR
> > Y !=
> > +            PCI_COMMAND_MEMORY);
> > +    BUILD_BUG_ON((typeof(*pci_devfn_decode_type))PCI_COMMAND_MASTE
> > R !=
> > +            PCI_COMMAND_MASTER);
> 
> Indentation here still looks wrong, despite me having given you
> the precise form to use in reply to v4. This can be taken care
> of while committing (if no other need for a v6 arises), but it
> would have been nice if you had done this as indicated.
> 
This is due to my vimrc configuration. I will fix this while comitting
to align second line to begin with typeof

> Jan