staging: unisys: visorbus: fix s-Par to boot with option CONFIG_VMAP_STACK set to y

The root issue is that we are not allowed to have items on the
stack being passed to "DMA" like operations. In this case we have
vmcall operation that was using parameters from the stack.

This patch fixes the issue by moving the variables on stack in
issue_vmcall_io_controlvm_addr() to vmcall_controlvm_addr struct.
Signed-off-by: Sameer Wadgaonkar <sameer.wadgaonkar@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/unisys/visorbus/visorchipset.c

@@ -57,6 +57,12 @@ struct parser_context {
 	char data[0];
 };
 
+struct vmcall_controlvm_addr {
+	struct vmcall_io_controlvm_addr_params params;
+	int err;
+	u64 physaddr;
+};
+
 struct visorchipset_device {
 	struct acpi_device *acpi_device;
 	unsigned long poll_jiffies;
@@ -74,6 +80,7 @@ struct visorchipset_device {
 	 */
 	struct controlvm_message controlvm_pending_msg;
 	bool controlvm_pending_msg_valid;
+	struct vmcall_controlvm_addr controlvm_addr;
 };
 
 static struct visorchipset_device *chipset_dev;
@@ -1338,17 +1345,15 @@ static int unisys_vmcall(unsigned long tuple, unsigned long param)
 static unsigned int
 issue_vmcall_io_controlvm_addr(u64 *control_addr, u32 *control_bytes)
 {
-	struct vmcall_io_controlvm_addr_params params;
-	int err;
-	u64 physaddr;
+	chipset_dev->controlvm_addr.physaddr = virt_to_phys(
+					   &chipset_dev->controlvm_addr.params);
+	chipset_dev->controlvm_addr.err = unisys_vmcall(VMCALL_CONTROLVM_ADDR,
+					  chipset_dev->controlvm_addr.physaddr);
+	if (chipset_dev->controlvm_addr.err)
+		return chipset_dev->controlvm_addr.err;
 
-	physaddr = virt_to_phys(&params);
-	err = unisys_vmcall(VMCALL_CONTROLVM_ADDR, physaddr);
-	if (err)
-		return err;
-
-	*control_addr = params.address;
-	*control_bytes = params.channel_bytes;
+	*control_addr = chipset_dev->controlvm_addr.params.address;
+	*control_bytes = chipset_dev->controlvm_addr.params.channel_bytes;
 
 	return 0;
 }
@@ -1819,14 +1824,14 @@ visorchipset_init(struct acpi_device *acpi_device)
 	uuid_le uuid = SPAR_CONTROLVM_CHANNEL_PROTOCOL_UUID;
 	struct visorchannel *controlvm_channel;
 
-	addr = controlvm_get_channel_address();
-	if (!addr)
-		goto error;
-
 	chipset_dev = kzalloc(sizeof(*chipset_dev), GFP_KERNEL);
 	if (!chipset_dev)
 		goto error;
 
+	addr = controlvm_get_channel_address();
+	if (!addr)
+		goto error;
+
 	acpi_device->driver_data = chipset_dev;
 
 	chipset_dev->acpi_device = acpi_device;