[v10,4/4] PCI: Allow extend_bridge_window() to shrink resource if necessary
diff mbox series

Message ID SL2P216MB0187C1ACBE716693FD5622BD80600@SL2P216MB0187.KORP216.PROD.OUTLOOK.COM
State New
Delegated to: Bjorn Helgaas
Headers show
Series
  • Untitled series #139629
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Commit Message

Nicholas Johnson Oct. 30, 2019, 12:47 p.m. UTC
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@outlook.com.au>
---
 drivers/pci/setup-bus.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

Comments

Mika Westerberg Oct. 30, 2019, 1:25 p.m. UTC | #1
On Wed, Oct 30, 2019 at 12:47:44PM +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@outlook.com.au>

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Nicholas Johnson Oct. 30, 2019, 1:33 p.m. UTC | #2
On Wed, Oct 30, 2019 at 03:25:09PM +0200, mika.westerberg@linux.intel.com wrote:
> On Wed, Oct 30, 2019 at 12:47:44PM +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@outlook.com.au>
> 
> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Do I need to re-post with this line in it?

Cheers!
Mika Westerberg Oct. 30, 2019, 1:49 p.m. UTC | #3
On Wed, Oct 30, 2019 at 01:33:26PM +0000, Nicholas Johnson wrote:
> On Wed, Oct 30, 2019 at 03:25:09PM +0200, mika.westerberg@linux.intel.com wrote:
> > On Wed, Oct 30, 2019 at 12:47:44PM +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@outlook.com.au>
> > 
> > Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> Do I need to re-post with this line in it?

No. Typically maintainers add these when they apply the patch.
Nicholas Johnson Oct. 31, 2019, 2:34 p.m. UTC | #4
On Wed, Oct 30, 2019 at 03:49:39PM +0200, mika.westerberg@linux.intel.com wrote:
> On Wed, Oct 30, 2019 at 01:33:26PM +0000, Nicholas Johnson wrote:
> > On Wed, Oct 30, 2019 at 03:25:09PM +0200, mika.westerberg@linux.intel.com wrote:
> > > On Wed, Oct 30, 2019 at 12:47:44PM +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@outlook.com.au>
> > > 
> > > Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> > Do I need to re-post with this line in it?
> 
> No. Typically maintainers add these when they apply the patch.
Cheers, only 1/4 (the biggest one) is left to review. I will try to post 
the patch for the bugfix again soon, also.

Patch
diff mbox series

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index d83c55169..6b64bf909 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1814,22 +1814,29 @@  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)
 {
-	resource_size_t add_size;
+	resource_size_t add_size, size = resource_size(res);
 
 	if (res->parent)
 		return;
 
-	if (resource_size(res) >= new_size)
-		return;
+	if (new_size > size) {
+		add_size = new_size - size;
+		pci_dbg(bridge, "bridge window %pR extended by %pa\n", res,
+			&add_size);
+	} else if (new_size < size) {
+		add_size = size - new_size;
+		pci_dbg(bridge, "bridge window %pR shrunken by %pa\n", res,
+			&add_size);
+	}
 
-	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);
 }
 
 static void pci_bus_distribute_available_resources(struct pci_bus *bus,
@@ -1865,9 +1872,9 @@  static void pci_bus_distribute_available_resources(struct pci_bus *bus,
 	 * Update the resources to fill as much remaining resource space in the
 	 * parent bridge as possible, while considering alignment.
 	 */
-	extend_bridge_window(bridge, io_res, add_list, resource_size(&io));
-	extend_bridge_window(bridge, mmio_res, add_list, resource_size(&mmio));
-	extend_bridge_window(bridge, mmio_pref_res, add_list,
+	adjust_bridge_window(bridge, io_res, add_list, resource_size(&io));
+	adjust_bridge_window(bridge, mmio_res, add_list, resource_size(&mmio));
+	adjust_bridge_window(bridge, mmio_pref_res, add_list,
 			     resource_size(&mmio_pref));
 
 	/*