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

[Bjorn Helgaas <helgaas@kernel.org>]

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].

> +		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
>