1 files changed, 36 insertions, 1 deletions

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index dfc6149ccc93..eaa5c3b7fd8a 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -41,6 +41,7 @@
 #include <linux/ptrace.h>
 #include <linux/screen_info.h>
 #include <linux/kdebug.h>
+#include <linux/efi.h>
 #include "hyperv_vmbus.h"
 
 static struct acpi_device  *hv_acpi_dev;
@@ -101,6 +102,8 @@ static struct notifier_block hyperv_panic_block = {
         .notifier_call = hyperv_panic_event,
 };
 
+static const char *fb_mmio_name = "fb_range";
+static struct resource *fb_mmio;
 struct resource *hyperv_mmio;
 DEFINE_SEMAPHORE(hyperv_mmio_lock);
 
@@ -1091,6 +1094,12 @@ static int vmbus_acpi_remove(struct acpi_device *device)
         struct resource *next_res;
 
         if (hyperv_mmio) {
+                if (fb_mmio) {
+                        __release_region(hyperv_mmio, fb_mmio->start,
+                                         resource_size(fb_mmio));
+                        fb_mmio = NULL;
+                }
+
                 for (cur_res = hyperv_mmio; cur_res; cur_res = next_res) {
                         next_res = cur_res->sibling;
                         kfree(cur_res);
@@ -1100,6 +1109,30 @@ static int vmbus_acpi_remove(struct acpi_device *device)
         return 0;
 }
 
+static void vmbus_reserve_fb(void)
+{
+        int size;
+        /*
+         * Make a claim for the frame buffer in the resource tree under the
+         * first node, which will be the one below 4GB.  The length seems to
+         * be underreported, particularly in a Generation 1 VM.  So start out
+         * reserving a larger area and make it smaller until it succeeds.
+         */
+
+        if (screen_info.lfb_base) {
+                if (efi_enabled(EFI_BOOT))
+                        size = max_t(__u32, screen_info.lfb_size, 0x800000);
+                else
+                        size = max_t(__u32, screen_info.lfb_size, 0x4000000);
+
+                for (; !fb_mmio && (size >= 0x100000); size >>= 1) {
+                        fb_mmio = __request_region(hyperv_mmio,
+                                                   screen_info.lfb_base, size,
+                                                   fb_mmio_name, 0);
+                }
+        }
+}
+
 /**
  * vmbus_allocate_mmio() - Pick a memory-mapped I/O range.
  * @new:                If successful, supplied a pointer to the
@@ -1261,8 +1294,10 @@ static int vmbus_acpi_add(struct acpi_device *device)
 
                 if (ACPI_FAILURE(result))
                         continue;
-                if (hyperv_mmio)
+                if (hyperv_mmio) {
+                        vmbus_reserve_fb();
                         break;
+                }
         }
         ret_val = 0;