From: Jake Oshins <jakeo@microsoft.com>
Date: Tue, 15 Dec 2015 00:01:52 +0000 (-0800)
Subject: drivers:hv: Allow for MMIO claims that span ACPI _CRS records
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=40f26f3168bf7a4da490db308dc0bd9f9923f41f;p=linux.git

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 f123bca778086..328e4c3808e06 100644
--- 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)