@@ -5049,6 +5049,48 @@ static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev)
return align;
}
+static void pci_request_resource_alignment(struct pci_dev *dev, int bar,
+ resource_size_t align)
+{
+ struct resource *r = &dev->resource[bar];
+ resource_size_t size;
+
+ if (!(r->flags & IORESOURCE_MEM))
+ return;
+
+ if (r->flags & IORESOURCE_PCI_FIXED) {
+ dev_info(&dev->dev, "BAR%d %pR: ignoring requested alignment %#llx\n",
+ bar, r, (unsigned long long)align);
+ return;
+ }
+
+ size = resource_size(r);
+ if (size < align) {
+
+ /*
+ * Increase the size of the resource. BARs are aligned on
+ * their size, so when we reallocate space for this
+ * resource, we'll allocate it with the larger alignment.
+ * It also prevents assignment of any other BARs inside the
+ * size. If we're requesting page alignment, this means no
+ * other BARs will share the page.
+ *
+ * This makes the resource larger than the hardware BAR,
+ * which may break drivers that compute things based on the
+ * resource size, e.g., to find registers at a fixed offset
+ * before the end of the BAR. We hope users don't request
+ * alignment for such devices.
+ */
+ size = align;
+ dev_info(&dev->dev, "BAR%d %pR: requesting alignment to %#llx\n",
+ bar, r, (unsigned long long)align);
+
+ }
+ r->flags |= IORESOURCE_UNSET;
+ r->end = size - 1;
+ r->start = 0;
+}
+
/*
* This function disables memory decoding and releases memory resources
* of the device specified by kernel's boot parameter 'pci=resource_alignment='.
@@ -5090,28 +5132,11 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev)
command &= ~PCI_COMMAND_MEMORY;
pci_write_config_word(dev, PCI_COMMAND, command);
- for (i = 0; i <= PCI_ROM_RESOURCE; i++) {
- r = &dev->resource[i];
- if (!(r->flags & IORESOURCE_MEM))
- continue;
- if (r->flags & IORESOURCE_PCI_FIXED) {
- dev_info(&dev->dev, "Ignoring requested alignment for BAR%d: %pR\n",
- i, r);
- continue;
- }
+ for (i = 0; i <= PCI_ROM_RESOURCE; i++)
+ pci_request_resource_alignment(dev, i, align);
- size = resource_size(r);
- if (size < align) {
- size = align;
- dev_info(&dev->dev,
- "Rounding up size of resource #%d to %#llx.\n",
- i, (unsigned long long)size);
- }
- r->flags |= IORESOURCE_UNSET;
- r->end = size - 1;
- r->start = 0;
- }
- /* Need to disable bridge's resource window,
+ /*
+ * Need to disable bridge's resource window,
* to enable the kernel to reassign new resource
* window later on.
*/
Pull the BAR size adjustment out into a new function, pci_request_resource_alignment(), and add a comment about how and why we increase the resource size and alignment. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> --- drivers/pci/pci.c | 67 ++++++++++++++++++++++++++++++++++++----------------- 1 file changed, 46 insertions(+), 21 deletions(-)