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


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