On Sat, Jan 09, 2021 at 10:53:53AM +0100, Ard Biesheuvel wrote:
> The _DSM #5 method in the ACPI host bridge object tells us whether the
> OS is permitted to deviate from the resource assignment configured by
> the firmware. If this is not the case, we should not permit drivers to
> resize BARs on the fly. So make pci_resize_resource() take this into
> account.
>
> Cc: <stable@xxxxxxxxxxxxxxx> # v5.4+
> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Capitalized subject to match convention and applied to pci/resource
for v5.11, thanks!
Is there an email, bug report, etc that prompted this change?
> ---
> drivers/pci/setup-res.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
> index 43eda101fcf4..3b38be081e93 100644
> --- a/drivers/pci/setup-res.c
> +++ b/drivers/pci/setup-res.c
> @@ -410,10 +410,16 @@ EXPORT_SYMBOL(pci_release_resource);
> int pci_resize_resource(struct pci_dev *dev, int resno, int size)
> {
> struct resource *res = dev->resource + resno;
> + struct pci_host_bridge *host;
> int old, ret;
> u32 sizes;
> u16 cmd;
>
> + /* Check if we must preserve the firmware's resource assignment */
> + host = pci_find_host_bridge(dev->bus);
> + if (host->preserve_config)
> + return -ENOTSUPP;
> +
> /* Make sure the resource isn't assigned before resizing it. */
> if (!(res->flags & IORESOURCE_UNSET))
> return -EBUSY;
> --
> 2.17.1
>
