From: Jake Oshins <ja...@microsoft.com>

This patch changes the logic in hv_vmbus to record all of the ranges in the
VM's firmware (BIOS or UEFI) that offer regions of memory-mapped I/O space for
use by paravirtual front-end drivers.  The old logic just found one range
above 4GB and called it good.  This logic will find any ranges above 1MB.

Signed-off-by: Jake Oshins <ja...@microsoft.com>
---
 drivers/hv/vmbus_drv.c          | 116 +++++++++++++++++++++++++++++++---------
 drivers/video/fbdev/hyperv_fb.c |   2 +-
 include/linux/hyperv.h          |   2 +-
 3 files changed, 92 insertions(+), 28 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index cf20400..398edc9 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -72,10 +72,7 @@ static struct notifier_block hyperv_panic_block = {
        .notifier_call = hyperv_panic_event,
 };
 
-struct resource hyperv_mmio = {
-       .name  = "hyperv mmio",
-       .flags = IORESOURCE_MEM,
-};
+struct resource *hyperv_mmio;
 EXPORT_SYMBOL_GPL(hyperv_mmio);
 
 static int vmbus_exists(void)
@@ -982,30 +979,105 @@ void vmbus_device_unregister(struct hv_device 
*device_obj)
 
 
 /*
- * VMBUS is an acpi enumerated device. Get the the information we
+ * VMBUS is an acpi enumerated device. Get the information we
  * need from DSDT.
  */
-
+#define VTPM_BASE_ADDRESS 0xfed40000
 static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx)
 {
+       resource_size_t start = 0;
+       resource_size_t end = 0;
+       struct resource *new_res;
+       struct resource **old_res = &hyperv_mmio;
+       struct resource **prev_res = NULL;
+
        switch (res->type) {
        case ACPI_RESOURCE_TYPE_IRQ:
                irq = res->data.irq.interrupts[0];
+               return AE_OK;
+
+       /*
+        * "Address" descriptors are for bus windows. Ignore
+        * "memory" descriptors, which are for registers on
+        * devices.
+        */
+       case ACPI_RESOURCE_TYPE_ADDRESS32:
+               start = res->data.address32.address.minimum;
+               end = res->data.address32.address.maximum;
                break;
 
        case ACPI_RESOURCE_TYPE_ADDRESS64:
-               hyperv_mmio.start = res->data.address64.address.minimum;
-               hyperv_mmio.end = res->data.address64.address.maximum;
+               start = res->data.address64.address.minimum;
+               end = res->data.address64.address.maximum;
                break;
+
+       default:
+               /* Unused resource type */
+               return AE_OK;
+
        }
+       /*
+        * Ignore ranges that are below 1MB, as they're not
+        * necessary or useful here.
+        */
+       if (end < 0x100000)
+               return AE_OK;
+
+       new_res = kzalloc(sizeof(*new_res), GFP_ATOMIC);
+       if (!new_res)
+               return AE_NO_MEMORY;
+
+       /* If this range overlaps the virtual TPM, truncate it. */
+       if (end > VTPM_BASE_ADDRESS && start < VTPM_BASE_ADDRESS)
+               end = VTPM_BASE_ADDRESS;
+
+       new_res->name = "hyperv mmio";
+       new_res->flags = IORESOURCE_MEM;
+       new_res->start = start;
+       new_res->end = end;
+
+       do {
+               if (!*old_res) {
+                       *old_res = new_res;
+                       break;
+               }
+
+               if ((*old_res)->end < new_res->start) {
+                       new_res->sibling = *old_res;
+                       if (prev_res)
+                               (*prev_res)->sibling = new_res;
+                       *old_res = new_res;
+                       break;
+               }
+
+               prev_res = old_res;
+               old_res = &(*old_res)->sibling;
+
+       } while (1);
 
        return AE_OK;
 }
 
+static int vmbus_acpi_remove(struct acpi_device *device)
+{
+       struct resource *cur_res;
+       struct resource *next_res;
+
+       if (hyperv_mmio) {
+               for (cur_res = hyperv_mmio; cur_res; cur_res = next_res) {
+                       next_res = cur_res->sibling;
+                       kfree(cur_res);
+               }
+       }
+
+       return 0;
+}
+
 static int vmbus_acpi_add(struct acpi_device *device)
 {
        acpi_status result;
        int ret_val = -ENODEV;
+       struct acpi_device *ancestor;
 
        hv_acpi_dev = device;
 
@@ -1015,35 +1087,27 @@ static int vmbus_acpi_add(struct acpi_device *device)
        if (ACPI_FAILURE(result))
                goto acpi_walk_err;
        /*
-        * The parent of the vmbus acpi device (Gen2 firmware) is the VMOD that
-        * has the mmio ranges. Get that.
+        * Some ancestor of the vmbus acpi device (Gen1 or Gen2
+        * firmware) is the VMOD that has the mmio ranges. Get that.
         */
-       if (device->parent) {
-               result = acpi_walk_resources(device->parent->handle,
-                                       METHOD_NAME__CRS,
-                                       vmbus_walk_resources, NULL);
+       for (ancestor = device->parent; ancestor; ancestor = ancestor->parent) {
+               result = acpi_walk_resources(ancestor->handle, METHOD_NAME__CRS,
+                                            vmbus_walk_resources, NULL);
 
                if (ACPI_FAILURE(result))
-                       goto acpi_walk_err;
-               if (hyperv_mmio.start && hyperv_mmio.end)
-                       request_resource(&iomem_resource, &hyperv_mmio);
+                       continue;
+               if (hyperv_mmio)
+                       break;
        }
        ret_val = 0;
 
 acpi_walk_err:
        complete(&probe_event);
+       if (ret_val)
+               vmbus_acpi_remove(device);
        return ret_val;
 }
 
-static int vmbus_acpi_remove(struct acpi_device *device)
-{
-       int ret = 0;
-
-       if (hyperv_mmio.start && hyperv_mmio.end)
-               ret = release_resource(&hyperv_mmio);
-       return ret;
-}
-
 static const struct acpi_device_id vmbus_acpi_device_ids[] = {
        {"VMBUS", 0},
        {"VMBus", 0},
diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
index 807ee22..b54ee1c 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -688,7 +688,7 @@ static int hvfb_getmem(struct fb_info *info)
        par->mem.name = KBUILD_MODNAME;
        par->mem.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
        if (gen2vm) {
-               ret = allocate_resource(&hyperv_mmio, &par->mem,
+               ret = allocate_resource(hyperv_mmio, &par->mem,
                                        screen_fb_size,
                                        0, -1,
                                        screen_fb_size,
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 30d3a1f..217e14b 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1233,7 +1233,7 @@ extern bool vmbus_prep_negotiate_resp(struct icmsg_hdr *,
 
 void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid);
 
-extern struct resource hyperv_mmio;
+extern struct resource *hyperv_mmio;
 
 /*
  * Negotiated version with the Host.
-- 
1.9.1

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