From: Gerd Hoffmann <kraxel@redhat.com>
Subject: [RHEL5.1 patch] xen, bug 219652: kill sys_{lock,unlock} dependency  on microcode driver
Date: Fri, 11 May 2007 15:22:57 +0200
Bugzilla: 219652
Message-Id: <46446E31.5080007@redhat.com>
Changelog: [misc] xen: kill sys_{lock,unlock} dependency on microcode driver


  Hi folks,

bug 219652

The attached patch fixes the xen microcode driver to not depend on 
sys_mlock and sys_munlock symbols any more.  This allows to build 
kernel-xen with a modular microcode driver.

Together with that patch the CONFIG_MICROCODE should be changed from "y" 
to "m" for xen kernels, so xen and native kernel are configured the same 
way.

Patch is backported from xen-3.1 and rediffed to apply cleanly to the 
current rhel-5 kernel.

cheers,
  Gerd

# HG changeset patch
# User kfraser@localhost.localdomain
# Date 1161189696 -3600
# Node ID 9943e06e966e24773459c654975310f36ba5daa2
# Parent  7f861cd3d0c3508612c9e5cf92ec8ff362645cb7
[LINUX] Eliminate microcode driver's dependency on sys_m{,un}lock as
well as the needless use of static variables.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

---
 arch/i386/kernel/microcode-xen.c |   37 ++++++++++++++++---------------------
 1 file changed, 16 insertions(+), 21 deletions(-)

Index: linux-2.6.18.noarch/arch/i386/kernel/microcode-xen.c
===================================================================
--- linux-2.6.18.noarch.orig/arch/i386/kernel/microcode-xen.c
+++ linux-2.6.18.noarch/arch/i386/kernel/microcode-xen.c
@@ -52,8 +52,6 @@ MODULE_LICENSE("GPL");
 /* no concurrent ->write()s are allowed on /dev/cpu/microcode */
 static DEFINE_MUTEX(microcode_mutex);
 
-static void __user *user_buffer;	/* user area microcode data buffer */
-static unsigned int user_buffer_size;	/* it's size */
 				
 static int microcode_open (struct inode *unused1, struct file *unused2)
 {
@@ -61,21 +59,26 @@ static int microcode_open (struct inode 
 }
 
 
-static int do_microcode_update (void)
+static int do_microcode_update (const void __user *ubuf, size_t len)
 {
 	int err;
-	dom0_op_t op;
+	void *kbuf;
 
-	err = sys_mlock((unsigned long)user_buffer, user_buffer_size);
-	if (err != 0)
-		return err;
+	kbuf = vmalloc(len);
+	if (!kbuf)
+		return -ENOMEM;
 
-	op.cmd = DOM0_MICROCODE;
-	set_xen_guest_handle(op.u.microcode.data, user_buffer);
-	op.u.microcode.length = user_buffer_size;
-	err = HYPERVISOR_dom0_op(&op);
+	if (copy_from_user(kbuf, ubuf, len) == 0) {
+		dom0_op_t op;
 
-	(void)sys_munlock((unsigned long)user_buffer, user_buffer_size);
+		op.cmd = DOM0_MICROCODE;
+		set_xen_guest_handle(op.u.microcode.data, kbuf);
+		op.u.microcode.length = len;
+		err = HYPERVISOR_dom0_op(&op);
+	} else
+		err = -EFAULT;
+
+	vfree(kbuf);
 
 	return err;
 }
@@ -89,17 +92,9 @@ static ssize_t microcode_write (struct f
 		return -EINVAL;
 	}
 
-	if ((len >> PAGE_SHIFT) > num_physpages) {
-		printk(KERN_ERR "microcode: too much data (max %ld pages)\n", num_physpages);
-		return -EINVAL;
-	}
-
 	mutex_lock(&microcode_mutex);
 
-	user_buffer = (void __user *) buf;
-	user_buffer_size = (int) len;
-
-	ret = do_microcode_update();
+	ret = do_microcode_update(buf, len);
 	if (!ret)
 		ret = (ssize_t)len;