[PATCH 0/2] Drivers: hv: vmbus: Change memory-mapped I/O management for Hyper-V paravirt

[PATCH 0/2] Drivers: hv: vmbus: Change memory-mapped I/O management for Hyper-V paravirt

[K. Y. Srinivasan]

This patch series changes the way that hv_vmbus searches for ranges of 
memory-mapped I/O space (MMIO) which can be used by its children.  The old
way just found the one and only range above 4GB.  This one makes all ranges
exposed in the VM's firmware potential candidates.  It also moves the code
which chooses ranges from hyperv_fb (the video front-end driver for Hyper-V)
to hv_vmbus.


jakeo@microsoft.com (2):
  drivers:hv: Modify hv_vmbus to search for all MMIO ranges available.
  drivers:hv: Move MMIO range picking from hyper_fb to hv_vmbus

 drivers/hv/vmbus_drv.c          |  204 +++++++++++++++++++++++++++++++++------
 drivers/video/fbdev/hyperv_fb.c |   46 ++++-----
 include/linux/hyperv.h          |    7 +-
 3 files changed, 200 insertions(+), 57 deletions(-)

-- 
1.7.4.1

[PATCH 0/2] Drivers: hv: vmbus: Change memory-mapped I/O management for Hyper-V paravirt

[K. Y. Srinivasan]

This patch series changes the way that hv_vmbus searches for ranges of 
memory-mapped I/O space (MMIO) which can be used by its children.  The old
way just found the one and only range above 4GB.  This one makes all ranges
exposed in the VM's firmware potential candidates.  It also moves the code
which chooses ranges from hyperv_fb (the video front-end driver for Hyper-V)
to hv_vmbus.


jakeo@microsoft.com (2):
  drivers:hv: Modify hv_vmbus to search for all MMIO ranges available.
  drivers:hv: Move MMIO range picking from hyper_fb to hv_vmbus

 drivers/hv/vmbus_drv.c          |  204 +++++++++++++++++++++++++++++++++------
 drivers/video/fbdev/hyperv_fb.c |   46 ++++-----
 include/linux/hyperv.h          |    7 +-
 3 files changed, 200 insertions(+), 57 deletions(-)

-- 
1.7.4.1

[PATCH 1/2] drivers:hv: Modify hv_vmbus to search for all MMIO ranges available.

[K. Y. Srinivasan]

From: jakeo@microsoft.com <jakeo@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.

It would have been possible with this patch to just use existing resource
allocation functions, rather than keep track of the entire set of Hyper-V
related MMIO regions in VMBus.  This strategy, however, is not sufficient
when the resource allocator needs to be aware of the constraints of a
Hyper-V virtual machine, which is what happens in the next patch in the series.
So this first patch exists to show the first steps in reworking the MMIO
allocation paths for Hyper-V front-end drivers.

Signed-off-by: Jake Oshins <jakeo@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@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 b6114cc..21bb287 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -102,10 +102,7 @@ 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)
@@ -1013,30 +1010,105 @@ 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;
 
@@ -1046,35 +1118,27 @@ 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.
-- 
1.7.4.1

[PATCH 1/2] drivers:hv: Modify hv_vmbus to search for all MMIO ranges available.

[K. Y. Srinivasan]

From: jakeo@microsoft.com <jakeo@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.

It would have been possible with this patch to just use existing resource
allocation functions, rather than keep track of the entire set of Hyper-V
related MMIO regions in VMBus.  This strategy, however, is not sufficient
when the resource allocator needs to be aware of the constraints of a
Hyper-V virtual machine, which is what happens in the next patch in the series.
So this first patch exists to show the first steps in reworking the MMIO
allocation paths for Hyper-V front-end drivers.

Signed-off-by: Jake Oshins <jakeo@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@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 b6114cc..21bb287 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -102,10 +102,7 @@ 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)
@@ -1013,30 +1010,105 @@ 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;
 
@@ -1046,35 +1118,27 @@ 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.
-- 
1.7.4.1

[PATCH 2/2] drivers:hv: Move MMIO range picking from hyper_fb to hv_vmbus

[K. Y. Srinivasan]

From: jakeo@microsoft.com <jakeo@microsoft.com>

This patch deletes the logic from hyperv_fb which picked a range of MMIO space
for the frame buffer and adds new logic to hv_vmbus which picks ranges for
child drivers.  The new logic isn't quite the same as the old, as it considers
more possible ranges.

Signed-off-by: Jake Oshins <jakeo@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/vmbus_drv.c          |   88 +++++++++++++++++++++++++++++++++++++--
 drivers/video/fbdev/hyperv_fb.c |   46 +++++++++-----------
 include/linux/hyperv.h          |    7 ++-
 3 files changed, 110 insertions(+), 31 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 21bb287..83759c1 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -39,6 +39,7 @@
 #include <asm/mshyperv.h>
 #include <linux/notifier.h>
 #include <linux/ptrace.h>
+#include <linux/screen_info.h>
 #include <linux/kdebug.h>
 #include "hyperv_vmbus.h"
 
@@ -103,7 +104,6 @@ static struct notifier_block hyperv_panic_block = {
 };
 
 struct resource *hyperv_mmio;
-EXPORT_SYMBOL_GPL(hyperv_mmio);
 
 static int vmbus_exists(void)
 {
@@ -891,8 +891,8 @@ err_cleanup:
 }
 
 /**
- * __vmbus_child_driver_register - Register a vmbus's driver
- * @drv: Pointer to driver structure you want to register
+ * __vmbus_child_driver_register() - Register a vmbus's driver
+ * @hv_driver: Pointer to driver structure you want to register
  * @owner: owner module of the drv
  * @mod_name: module name string
  *
@@ -924,7 +924,8 @@ EXPORT_SYMBOL_GPL(__vmbus_driver_register);
 
 /**
  * vmbus_driver_unregister() - Unregister a vmbus's driver
- * @drv: Pointer to driver structure you want to un-register
+ * @hv_driver: Pointer to driver structure you want to
+ *             un-register
  *
  * Un-register the given driver that was previous registered with a call to
  * vmbus_driver_register()
@@ -1104,6 +1105,85 @@ static int vmbus_acpi_remove(struct acpi_device *device)
 	return 0;
 }
 
+/**
+ * vmbus_allocate_mmio() - Pick a memory-mapped I/O range.
+ * @new:		If successful, supplied a pointer to the
+ *			allocated MMIO space.
+ * @device_obj:		Identifies the caller
+ * @min:		Minimum guest physical address of the
+ *			allocation
+ * @max:		Maximum guest physical address
+ * @size:		Size of the range to be allocated
+ * @align:		Alignment of the range to be allocated
+ * @fb_overlap_ok:	Whether this allocation can be allowed
+ *			to overlap the video frame buffer.
+ *
+ * This function walks the resources granted to VMBus by the
+ * _CRS object in the ACPI namespace underneath the parent
+ * "bridge" whether that's a root PCI bus in the Generation 1
+ * case or a Module Device in the Generation 2 case.  It then
+ * attempts to allocate from the global MMIO pool in a way that
+ * matches the constraints supplied in these parameters and by
+ * that _CRS.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
+			resource_size_t min, resource_size_t max,
+			resource_size_t size, resource_size_t align,
+			bool fb_overlap_ok)
+{
+	struct resource *iter;
+	resource_size_t range_min, range_max, start, local_min, local_max;
+	const char *dev_n = dev_name(&device_obj->device);
+	u32 fb_end = screen_info.lfb_base + (screen_info.lfb_size << 1);
+	int i;
+
+	for (iter = hyperv_mmio; iter; iter = iter->sibling) {
+		if ((iter->start >= max) || (iter->end <= min))
+			continue;
+
+		range_min = iter->start;
+		range_max = iter->end;
+
+		/* If this range overlaps the frame buffer, split it into
+		   two tries. */
+		for (i = 0; i < 2; i++) {
+			local_min = range_min;
+			local_max = range_max;
+			if (fb_overlap_ok || (range_min >= fb_end) ||
+			    (range_max <= screen_info.lfb_base)) {
+				i++;
+			} else {
+				if ((range_min <= screen_info.lfb_base) &&
+				    (range_max >= screen_info.lfb_base)) {
+					/*
+					 * The frame buffer is in this window,
+					 * so trim this into the part that
+					 * preceeds the frame buffer.
+					 */
+					local_max = screen_info.lfb_base - 1;
+					range_min = fb_end;
+				} else {
+					range_min = fb_end;
+					continue;
+				}
+			}
+
+			start = (local_min + align - 1) & ~(align - 1);
+			for (; start + size - 1 <= local_max; start += align) {
+				*new = request_mem_region_exclusive(start, size,
+								    dev_n);
+				if (*new)
+					return 0;
+			}
+		}
+	}
+
+	return -ENXIO;
+}
+EXPORT_SYMBOL_GPL(vmbus_allocate_mmio);
+
 static int vmbus_acpi_add(struct acpi_device *device)
 {
 	acpi_status result;
diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
index b54ee1c..e2451bd 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -213,7 +213,7 @@ struct synthvid_msg {
 
 struct hvfb_par {
 	struct fb_info *info;
-	struct resource mem;
+	struct resource *mem;
 	bool fb_ready; /* fb device is ready */
 	struct completion wait;
 	u32 synthvid_version;
@@ -677,26 +677,18 @@ static void hvfb_get_option(struct fb_info *info)
 
 
 /* Get framebuffer memory from Hyper-V video pci space */
-static int hvfb_getmem(struct fb_info *info)
+static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
 {
 	struct hvfb_par *par = info->par;
 	struct pci_dev *pdev  = NULL;
 	void __iomem *fb_virt;
 	int gen2vm = efi_enabled(EFI_BOOT);
+	resource_size_t pot_start, pot_end;
 	int ret;
 
-	par->mem.name = KBUILD_MODNAME;
-	par->mem.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 	if (gen2vm) {
-		ret = allocate_resource(hyperv_mmio, &par->mem,
-					screen_fb_size,
-					0, -1,
-					screen_fb_size,
-					NULL, NULL);
-		if (ret != 0) {
-			pr_err("Unable to allocate framebuffer memory\n");
-			return -ENODEV;
-		}
+		pot_start = 0;
+		pot_end = -1;
 	} else {
 		pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
 			      PCI_DEVICE_ID_HYPERV_VIDEO, NULL);
@@ -709,16 +701,18 @@ static int hvfb_getmem(struct fb_info *info)
 		    pci_resource_len(pdev, 0) < screen_fb_size)
 			goto err1;
 
-		par->mem.end = pci_resource_end(pdev, 0);
-		par->mem.start = par->mem.end - screen_fb_size + 1;
-		ret = request_resource(&pdev->resource[0], &par->mem);
-		if (ret != 0) {
-			pr_err("Unable to request framebuffer memory\n");
-			goto err1;
-		}
+		pot_end = pci_resource_end(pdev, 0);
+		pot_start = pot_end - screen_fb_size + 1;
+	}
+
+	ret = vmbus_allocate_mmio(&par->mem, hdev, pot_start, pot_end,
+				  screen_fb_size, 0x100000, true);
+	if (ret != 0) {
+		pr_err("Unable to allocate framebuffer memory\n");
+		goto err1;
 	}
 
-	fb_virt = ioremap(par->mem.start, screen_fb_size);
+	fb_virt = ioremap(par->mem->start, screen_fb_size);
 	if (!fb_virt)
 		goto err2;
 
@@ -736,7 +730,7 @@ static int hvfb_getmem(struct fb_info *info)
 		info->apertures->ranges[0].size = pci_resource_len(pdev, 0);
 	}
 
-	info->fix.smem_start = par->mem.start;
+	info->fix.smem_start = par->mem->start;
 	info->fix.smem_len = screen_fb_size;
 	info->screen_base = fb_virt;
 	info->screen_size = screen_fb_size;
@@ -749,7 +743,8 @@ static int hvfb_getmem(struct fb_info *info)
 err3:
 	iounmap(fb_virt);
 err2:
-	release_resource(&par->mem);
+	release_mem_region(par->mem->start, screen_fb_size);
+	par->mem = NULL;
 err1:
 	if (!gen2vm)
 		pci_dev_put(pdev);
@@ -763,7 +758,8 @@ static void hvfb_putmem(struct fb_info *info)
 	struct hvfb_par *par = info->par;
 
 	iounmap(info->screen_base);
-	release_resource(&par->mem);
+	release_mem_region(par->mem->start, screen_fb_size);
+	par->mem = NULL;
 }
 
 
@@ -794,7 +790,7 @@ static int hvfb_probe(struct hv_device *hdev,
 		goto error1;
 	}
 
-	ret = hvfb_getmem(info);
+	ret = hvfb_getmem(hdev, info);
 	if (ret) {
 		pr_err("No memory for framebuffer\n");
 		goto error2;
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 217e14b..54733d5 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -977,6 +977,11 @@ int __must_check __vmbus_driver_register(struct hv_driver *hv_driver,
 					 const char *mod_name);
 void vmbus_driver_unregister(struct hv_driver *hv_driver);
 
+int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
+			resource_size_t min, resource_size_t max,
+			resource_size_t size, resource_size_t align,
+			bool fb_overlap_ok);
+
 /**
  * VMBUS_DEVICE - macro used to describe a specific hyperv vmbus device
  *
@@ -1233,8 +1238,6 @@ 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;
-
 /*
  * Negotiated version with the Host.
  */
-- 
1.7.4.1

[PATCH 2/2] drivers:hv: Move MMIO range picking from hyper_fb to hv_vmbus

[K. Y. Srinivasan]

From: jakeo@microsoft.com <jakeo@microsoft.com>

This patch deletes the logic from hyperv_fb which picked a range of MMIO space
for the frame buffer and adds new logic to hv_vmbus which picks ranges for
child drivers.  The new logic isn't quite the same as the old, as it considers
more possible ranges.

Signed-off-by: Jake Oshins <jakeo@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/vmbus_drv.c          |   88 +++++++++++++++++++++++++++++++++++++--
 drivers/video/fbdev/hyperv_fb.c |   46 +++++++++-----------
 include/linux/hyperv.h          |    7 ++-
 3 files changed, 110 insertions(+), 31 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 21bb287..83759c1 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -39,6 +39,7 @@
 #include <asm/mshyperv.h>
 #include <linux/notifier.h>
 #include <linux/ptrace.h>
+#include <linux/screen_info.h>
 #include <linux/kdebug.h>
 #include "hyperv_vmbus.h"
 
@@ -103,7 +104,6 @@ static struct notifier_block hyperv_panic_block = {
 };
 
 struct resource *hyperv_mmio;
-EXPORT_SYMBOL_GPL(hyperv_mmio);
 
 static int vmbus_exists(void)
 {
@@ -891,8 +891,8 @@ err_cleanup:
 }
 
 /**
- * __vmbus_child_driver_register - Register a vmbus's driver
- * @drv: Pointer to driver structure you want to register
+ * __vmbus_child_driver_register() - Register a vmbus's driver
+ * @hv_driver: Pointer to driver structure you want to register
  * @owner: owner module of the drv
  * @mod_name: module name string
  *
@@ -924,7 +924,8 @@ EXPORT_SYMBOL_GPL(__vmbus_driver_register);
 
 /**
  * vmbus_driver_unregister() - Unregister a vmbus's driver
- * @drv: Pointer to driver structure you want to un-register
+ * @hv_driver: Pointer to driver structure you want to
+ *             un-register
  *
  * Un-register the given driver that was previous registered with a call to
  * vmbus_driver_register()
@@ -1104,6 +1105,85 @@ static int vmbus_acpi_remove(struct acpi_device *device)
 	return 0;
 }
 
+/**
+ * vmbus_allocate_mmio() - Pick a memory-mapped I/O range.
+ * @new:		If successful, supplied a pointer to the
+ *			allocated MMIO space.
+ * @device_obj:		Identifies the caller
+ * @min:		Minimum guest physical address of the
+ *			allocation
+ * @max:		Maximum guest physical address
+ * @size:		Size of the range to be allocated
+ * @align:		Alignment of the range to be allocated
+ * @fb_overlap_ok:	Whether this allocation can be allowed
+ *			to overlap the video frame buffer.
+ *
+ * This function walks the resources granted to VMBus by the
+ * _CRS object in the ACPI namespace underneath the parent
+ * "bridge" whether that's a root PCI bus in the Generation 1
+ * case or a Module Device in the Generation 2 case.  It then
+ * attempts to allocate from the global MMIO pool in a way that
+ * matches the constraints supplied in these parameters and by
+ * that _CRS.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
+			resource_size_t min, resource_size_t max,
+			resource_size_t size, resource_size_t align,
+			bool fb_overlap_ok)
+{
+	struct resource *iter;
+	resource_size_t range_min, range_max, start, local_min, local_max;
+	const char *dev_n = dev_name(&device_obj->device);
+	u32 fb_end = screen_info.lfb_base + (screen_info.lfb_size << 1);
+	int i;
+
+	for (iter = hyperv_mmio; iter; iter = iter->sibling) {
+		if ((iter->start >= max) || (iter->end <= min))
+			continue;
+
+		range_min = iter->start;
+		range_max = iter->end;
+
+		/* If this range overlaps the frame buffer, split it into
+		   two tries. */
+		for (i = 0; i < 2; i++) {
+			local_min = range_min;
+			local_max = range_max;
+			if (fb_overlap_ok || (range_min >= fb_end) ||
+			    (range_max <= screen_info.lfb_base)) {
+				i++;
+			} else {
+				if ((range_min <= screen_info.lfb_base) &&
+				    (range_max >= screen_info.lfb_base)) {
+					/*
+					 * The frame buffer is in this window,
+					 * so trim this into the part that
+					 * preceeds the frame buffer.
+					 */
+					local_max = screen_info.lfb_base - 1;
+					range_min = fb_end;
+				} else {
+					range_min = fb_end;
+					continue;
+				}
+			}
+
+			start = (local_min + align - 1) & ~(align - 1);
+			for (; start + size - 1 <= local_max; start += align) {
+				*new = request_mem_region_exclusive(start, size,
+								    dev_n);
+				if (*new)
+					return 0;
+			}
+		}
+	}
+
+	return -ENXIO;
+}
+EXPORT_SYMBOL_GPL(vmbus_allocate_mmio);
+
 static int vmbus_acpi_add(struct acpi_device *device)
 {
 	acpi_status result;
diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
index b54ee1c..e2451bd 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -213,7 +213,7 @@ struct synthvid_msg {
 
 struct hvfb_par {
 	struct fb_info *info;
-	struct resource mem;
+	struct resource *mem;
 	bool fb_ready; /* fb device is ready */
 	struct completion wait;
 	u32 synthvid_version;
@@ -677,26 +677,18 @@ static void hvfb_get_option(struct fb_info *info)
 
 
 /* Get framebuffer memory from Hyper-V video pci space */
-static int hvfb_getmem(struct fb_info *info)
+static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
 {
 	struct hvfb_par *par = info->par;
 	struct pci_dev *pdev  = NULL;
 	void __iomem *fb_virt;
 	int gen2vm = efi_enabled(EFI_BOOT);
+	resource_size_t pot_start, pot_end;
 	int ret;
 
-	par->mem.name = KBUILD_MODNAME;
-	par->mem.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 	if (gen2vm) {
-		ret = allocate_resource(hyperv_mmio, &par->mem,
-					screen_fb_size,
-					0, -1,
-					screen_fb_size,
-					NULL, NULL);
-		if (ret != 0) {
-			pr_err("Unable to allocate framebuffer memory\n");
-			return -ENODEV;
-		}
+		pot_start = 0;
+		pot_end = -1;
 	} else {
 		pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
 			      PCI_DEVICE_ID_HYPERV_VIDEO, NULL);
@@ -709,16 +701,18 @@ static int hvfb_getmem(struct fb_info *info)
 		    pci_resource_len(pdev, 0) < screen_fb_size)
 			goto err1;
 
-		par->mem.end = pci_resource_end(pdev, 0);
-		par->mem.start = par->mem.end - screen_fb_size + 1;
-		ret = request_resource(&pdev->resource[0], &par->mem);
-		if (ret != 0) {
-			pr_err("Unable to request framebuffer memory\n");
-			goto err1;
-		}
+		pot_end = pci_resource_end(pdev, 0);
+		pot_start = pot_end - screen_fb_size + 1;
+	}
+
+	ret = vmbus_allocate_mmio(&par->mem, hdev, pot_start, pot_end,
+				  screen_fb_size, 0x100000, true);
+	if (ret != 0) {
+		pr_err("Unable to allocate framebuffer memory\n");
+		goto err1;
 	}
 
-	fb_virt = ioremap(par->mem.start, screen_fb_size);
+	fb_virt = ioremap(par->mem->start, screen_fb_size);
 	if (!fb_virt)
 		goto err2;
 
@@ -736,7 +730,7 @@ static int hvfb_getmem(struct fb_info *info)
 		info->apertures->ranges[0].size = pci_resource_len(pdev, 0);
 	}
 
-	info->fix.smem_start = par->mem.start;
+	info->fix.smem_start = par->mem->start;
 	info->fix.smem_len = screen_fb_size;
 	info->screen_base = fb_virt;
 	info->screen_size = screen_fb_size;
@@ -749,7 +743,8 @@ static int hvfb_getmem(struct fb_info *info)
 err3:
 	iounmap(fb_virt);
 err2:
-	release_resource(&par->mem);
+	release_mem_region(par->mem->start, screen_fb_size);
+	par->mem = NULL;
 err1:
 	if (!gen2vm)
 		pci_dev_put(pdev);
@@ -763,7 +758,8 @@ static void hvfb_putmem(struct fb_info *info)
 	struct hvfb_par *par = info->par;
 
 	iounmap(info->screen_base);
-	release_resource(&par->mem);
+	release_mem_region(par->mem->start, screen_fb_size);
+	par->mem = NULL;
 }
 
 
@@ -794,7 +790,7 @@ static int hvfb_probe(struct hv_device *hdev,
 		goto error1;
 	}
 
-	ret = hvfb_getmem(info);
+	ret = hvfb_getmem(hdev, info);
 	if (ret) {
 		pr_err("No memory for framebuffer\n");
 		goto error2;
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 217e14b..54733d5 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -977,6 +977,11 @@ int __must_check __vmbus_driver_register(struct hv_driver *hv_driver,
 					 const char *mod_name);
 void vmbus_driver_unregister(struct hv_driver *hv_driver);
 
+int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
+			resource_size_t min, resource_size_t max,
+			resource_size_t size, resource_size_t align,
+			bool fb_overlap_ok);
+
 /**
  * VMBUS_DEVICE - macro used to describe a specific hyperv vmbus device
  *
@@ -1233,8 +1238,6 @@ 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;
-
 /*
  * Negotiated version with the Host.
  */
-- 
1.7.4.1

Re: [PATCH 1/2] drivers:hv: Modify hv_vmbus to search for all MMIO ranges available.

[Dan Carpenter]

On Tue, Jun 30, 2015 at 03:35:01PM -0700, K. Y. Srinivasan wrote:
> From: jakeo@microsoft.com <jakeo@microsoft.com>

Jake, fix your git config.

regards,
dan carpenter

Re: [PATCH 1/2] drivers:hv: Modify hv_vmbus to search for all MMIO ranges available.

[Dan Carpenter]

On Tue, Jun 30, 2015 at 03:35:01PM -0700, K. Y. Srinivasan wrote:
> From: jakeo@microsoft.com <jakeo@microsoft.com>

Jake, fix your git config.

regards,
dan carpenter

[PATCH 0/2] Change memory-mapped I/O management for Hyper-V paravirt

[jakeo]

From: Jake Oshins <jakeo@microsoft.com>

This patch series changes the way that hv_vmbus searches for ranges of 
memory-mapped I/O space (MMIO) which can be used by its children.  The old
way just found the one and only range above 4GB.  This one makes all ranges
exposed in the VM's firmware potential candidates.  It also moves the code
which chooses ranges from hyperv_fb (the video front-end driver for Hyper-V)
to hv_vmbus.

KY Srinivasan asked me to split this off from the previously submitted patch
series which introduced another front-end driver which needs this, because this
part stands on its own and constitutes a useful change in behavior.

Jake Oshins (2):
  drivers:hv: Modify hv_vmbus to search for all MMIO ranges available.
  drivers:hv: Move MMIO range picking from hyper_fb to hv_vmbus

 drivers/hv/vmbus_drv.c          | 204 ++++++++++++++++++++++++++++++++++------
 drivers/video/fbdev/hyperv_fb.c |  46 +++++----
 include/linux/hyperv.h          |   7 +-
 3 files changed, 200 insertions(+), 57 deletions(-)

-- 
1.9.1

[PATCH 1/2] drivers:hv: Modify hv_vmbus to search for all MMIO ranges available.

[jakeo]

From: Jake Oshins <jakeo@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 <jakeo@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