On Tue, Oct 29, 2019 at 03:29:21PM +0000, Nicholas Johnson wrote:
> Remove checks for resource size in extend_bridge_window(). This is
> necessary to allow the pci_bus_distribute_available_resources() to
> function when the kernel parameter pci=hpmemsize=nn[KMG] is used to
> allocate resources. Because the kernel parameter sets the size of all
> hotplug bridges to be the same, there are problems when nested hotplug
> bridges are encountered. Fitting a downstream hotplug bridge with size X
> and normal bridges with non-zero size Y into parent hotplug bridge with
> size X is impossible, and hence the downstream hotplug bridge needs to
> shrink to fit into its parent.
>
> Add check for if bridge is extended or shrunken and adjust pci_dbg to
> reflect this.
>
> Reset the resource if its new size is zero (if we have run out of a
> bridge window resource) to prevent the PCI resource assignment code from
> attempting to assign a zero-sized resource.
>
> Rename extend_bridge_window() to adjust_bridge_window() to reflect the
> fact that the window can now shrink.
>
> Signed-off-by: Nicholas Johnson <nicholas.johnson-opensource@xxxxxxxxxxxxxx>
> ---
> drivers/pci/setup-bus.c | 23 +++++++++++++++--------
> 1 file changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index fe8b2c715..f8cd54584 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -1814,7 +1814,7 @@ void __init pci_assign_unassigned_resources(void)
> }
> }
>
> -static void extend_bridge_window(struct pci_dev *bridge, struct resource *res,
> +static void adjust_bridge_window(struct pci_dev *bridge, struct resource *res,
> struct list_head *add_list,
> resource_size_t new_size)
> {
> @@ -1823,13 +1823,20 @@ static void extend_bridge_window(struct pci_dev *bridge, struct resource *res,
> if (res->parent)
> return;
>
> - if (resource_size(res) >= new_size)
> - return;
> + if (new_size > resource_size(res)) {
> + add_size = new_size - resource_size(res);
> + pci_dbg(bridge, "bridge window %pR extended by %pa\n", res,
> + &add_size);
> + } else if (new_size < resource_size(res)) {
> + add_size = resource_size(res) - new_size;
> + pci_dbg(bridge, "bridge window %pR shrunken by %pa\n", res,
> + &add_size);
> + }
Do we need to care about new_size == resource_size(res)?
Also there are several calls of resource_size(res) above so probably
worth storing it into a helper variable.
> - add_size = new_size - resource_size(res);
> - pci_dbg(bridge, "bridge window %pR extended by %pa\n", res, &add_size);
> res->end = res->start + new_size - 1;
> remove_from_list(add_list, res);
> + if (!new_size)
> + reset_resource(res);
> }
