From d6e0fbb82e73a01e4cb3631b8b3dd7aae09ab14c Mon Sep 17 00:00:00 2001
From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Date: Mon, 14 May 2018 09:27:40 +0300
Subject: ALSA: xen-front: Implement handling of shared buffers

Implement shared buffer handling according to the
para-virtualized sound device protocol at xen/interface/io/sndif.h:
  - manage buffer memory
  - handle granted references
  - handle page directories

[ Fixed missing linux/kernel.h inclusion -- tiwai ]

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/xen/xen_snd_front.c | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'sound/xen/xen_snd_front.c')

diff --git a/sound/xen/xen_snd_front.c b/sound/xen/xen_snd_front.c
index 277214d4fd0a..cdf66ea516c4 100644
--- a/sound/xen/xen_snd_front.c
+++ b/sound/xen/xen_snd_front.c
@@ -11,6 +11,7 @@
 #include <linux/delay.h>
 #include <linux/module.h>
 
+#include <xen/page.h>
 #include <xen/platform_pci.h>
 #include <xen/xen.h>
 #include <xen/xenbus.h>
@@ -191,6 +192,13 @@ static int __init xen_drv_init(void)
 	if (!xen_has_pv_devices())
 		return -ENODEV;
 
+	/* At the moment we only support case with XEN_PAGE_SIZE == PAGE_SIZE */
+	if (XEN_PAGE_SIZE != PAGE_SIZE) {
+		pr_err(XENSND_DRIVER_NAME ": different kernel and Xen page sizes are not supported: XEN_PAGE_SIZE (%lu) != PAGE_SIZE (%lu)\n",
+		       XEN_PAGE_SIZE, PAGE_SIZE);
+		return -ENODEV;
+	}
+
 	pr_info("Initialising Xen " XENSND_DRIVER_NAME " frontend driver\n");
 	return xenbus_register_frontend(&xen_driver);
 }
-- 
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