Re: [PATCH] PCI: vmd: Only assign _OSC features in bare metal OS.

[Nirmal Patel <nirmal.patel@linux.intel.com>]

On Tue, 30 Jun 2026 12:10:03 -0500
Bjorn Helgaas <helgaas@kernel.org> wrote:

> On Mon, Jun 29, 2026 at 05:02:43PM +0000, Nirmal Patel wrote:
> > From: Nirmal Patel <nirmal.patel@intel.com>
> > 
> > Copy valid _OSC flags from root bridge only when OS can provide
> > correct values. In virtual machine, all of the control features are
> > disabled as hypervisor will not passthrough root bridge information
> > to VM.
> > 
> > Signed-off-by: Nirmal Patel <nirmal.patel@linux.intel.com>
> > Reviewed-by:  Andy Shevchenko <andriy.shevchenko@intel.com>
> > ---
> >  drivers/pci/controller/vmd.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/vmd.c
> > b/drivers/pci/controller/vmd.c index d4ae250d4bc6..f9e38f2f926a
> > 100644 --- a/drivers/pci/controller/vmd.c
> > +++ b/drivers/pci/controller/vmd.c
> > @@ -910,8 +910,10 @@ static int vmd_enable_domain(struct vmd_dev
> > *vmd, unsigned long features) return -ENODEV;
> >  	}
> >  
> > -
> > vmd_copy_host_bridge_flags(pci_find_host_bridge(vmd->dev->bus),
> > -
> > to_pci_host_bridge(vmd->bus->bridge));
> > +	/* Don't copy _OSC control flags in VM, it disables
> > features.*/
> > +	if (!offset[0] || !offset[1])  
> 
> Drop period in subject line.
> 
> Replace period in comment with space.
> 
> Kind of a weird way to check for VM.  I see it's already done this way
> earlier in the function, but maybe it's time to add a descriptive
> boolean based on offset[0] and offset[1].

Thanks for the response, I will add a boolean implementation.
> 
> > +
> > vmd_copy_host_bridge_flags(pci_find_host_bridge(vmd->dev->bus),
> > +
> > to_pci_host_bridge(vmd->bus->bridge)); 
> >  	vmd_attach_resources(vmd);
> >  	if (vmd->irq_domain)
> > -- 
> > 2.43.0
> >