drivers:hv: Allow for MMIO claims that span ACPI _CRS records

This patch makes 16GB GPUs work in Hyper-V VMs, since, for
compatibility reasons, the Hyper-V BIOS lists MMIO ranges in 2GB
chunks in its root bus's _CRS object.

Signed-off-by: Jake Oshins <jakeo@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index f123bca..328e4c3 100644 (file)
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1063,12 +1063,28 @@ static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx)
        new_res->start = start;
        new_res->end = end;
 
+       /*
+        * Stick ranges from higher in address space at the front of the list.
+        * If two ranges are adjacent, merge them.
+        */
        do {
                if (!*old_res) {
                        *old_res = new_res;
                        break;
                }
 
+               if (((*old_res)->end + 1) == new_res->start) {
+                       (*old_res)->end = new_res->end;
+                       kfree(new_res);
+                       break;
+               }
+
+               if ((*old_res)->start == new_res->end + 1) {
+                       (*old_res)->start = new_res->start;
+                       kfree(new_res);
+                       break;
+               }
+
                if ((*old_res)->end < new_res->start) {
                        new_res->sibling = *old_res;
                        if (prev_res)