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From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org, virtualization@lists.osdl.org,
	xen-devel@lists.xensource.com,
	Ian Pratt <ian.pratt@xensource.com>,
	Christian Limpach <Christian.Limpach@cl.cam.ac.uk>,
	Chris Wright <chrisw@sous-sol.org>,
	"Jan Beulich" <JBeulich@novell.com>
Subject: [patch 18/20] XEN-paravirt: Add Xen driver utility functions.
Date: Fri, 12 Jan 2007 17:45:57 -0800	[thread overview]
Message-ID: <20070113014649.046041214@goop.org> (raw)
In-Reply-To: <20070113014539.408244126@goop.org>

[-- Attachment #1: xen-driver-util.patch --]
[-- Type: text/plain, Size: 3565 bytes --]

Allocate/destroy a 'vmalloc' VM area: alloc_vm_area and free_vm_area
The alloc function ensures that page tables are constructed for the
region of kernel virtual address space and mapped into init_mm.

Lock an area so that PTEs are accessible in the current address space:
lock_vm_area and unlock_vm_area
The lock function prevents context switches to a lazy mm that doesn't
have the area mapped into its page tables.  It also ensures that the
page tables are mapped into the current mm by causing the page fault
handler to copy the page directory pointers from init_mm into the
current mm.

Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: "Jan Beulich" <JBeulich@novell.com>
---

 drivers/xen/Makefile      |    2 +
 drivers/xen/util.c        |   70 ++++++++++++++++++++++++++++++++++++++++++++++
 include/xen/driver_util.h |   16 ++++++++++
 3 files changed, 88 insertions(+)

===================================================================
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -1,2 +1,4 @@ obj-y	+= core/
+obj-y	+= util.o
+
 obj-y	+= core/
 obj-y	+= console/
===================================================================
--- /dev/null
+++ b/drivers/xen/util.c
@@ -0,0 +1,69 @@
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <asm/uaccess.h>
+#include <xen/driver_util.h>
+
+static int f(pte_t *pte, struct page *pmd_page, unsigned long addr, void *data)
+{
+	/* apply_to_page_range() does all the hard work. */
+	return 0;
+}
+
+struct vm_struct *alloc_vm_area(unsigned long size)
+{
+	struct vm_struct *area;
+
+	area = get_vm_area(size, VM_IOREMAP);
+	if (area == NULL)
+		return NULL;
+
+	/*
+	 * This ensures that page tables are constructed for this region
+	 * of kernel virtual address space and mapped into init_mm.
+	 */
+	if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
+				area->size, f, NULL)) {
+		free_vm_area(area);
+		return NULL;
+	}
+
+	return area;
+}
+EXPORT_SYMBOL_GPL(alloc_vm_area);
+
+void free_vm_area(struct vm_struct *area)
+{
+	struct vm_struct *ret;
+	ret = remove_vm_area(area->addr);
+	BUG_ON(ret != area);
+	kfree(area);
+}
+EXPORT_SYMBOL_GPL(free_vm_area);
+
+void lock_vm_area(struct vm_struct *area)
+{
+	unsigned long i;
+	char c;
+
+	/*
+	 * Prevent context switch to a lazy mm that doesn't have this area
+	 * mapped into its page tables.
+	 */
+	preempt_disable();
+
+	/*
+	 * Ensure that the page tables are mapped into the current mm. The
+	 * page-fault path will copy the page directory pointers from init_mm.
+	 */
+	for (i = 0; i < area->size; i += PAGE_SIZE)
+		(void)__get_user(c, (char __user *)area->addr + i);
+}
+EXPORT_SYMBOL_GPL(lock_vm_area);
+
+void unlock_vm_area(struct vm_struct *area)
+{
+	preempt_enable();
+}
+EXPORT_SYMBOL_GPL(unlock_vm_area);
===================================================================
--- /dev/null
+++ b/include/xen/driver_util.h
@@ -0,0 +1,15 @@
+
+#ifndef __ASM_XEN_DRIVER_UTIL_H__
+#define __ASM_XEN_DRIVER_UTIL_H__
+
+#include <linux/vmalloc.h>
+
+/* Allocate/destroy a 'vmalloc' VM area. */
+extern struct vm_struct *alloc_vm_area(unsigned long size);
+extern void free_vm_area(struct vm_struct *area);
+
+/* Lock an area so that PTEs are accessible in the current address space. */
+extern void lock_vm_area(struct vm_struct *area);
+extern void unlock_vm_area(struct vm_struct *area);
+
+#endif /* __ASM_XEN_DRIVER_UTIL_H__ */

-- 


  parent reply	other threads:[~2007-01-13 23:15 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-13  1:45 [patch 00/20] XEN-paravirt: Xen guest implementation for paravirt_ops interface Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 01/20] XEN-paravirt: Fix typo in sync_constant_test_bit()s name Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 02/20] XEN-paravirt: Add a flag to allow the VGA console to be disabled Jeremy Fitzhardinge
2007-01-14  0:27   ` [Xen-devel] " Alan
2007-01-13  1:45 ` [patch 03/20] XEN-paravirt: paravirt: page-table accessors Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 04/20] XEN-paravirt: paravirt pagetable init Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 05/20] XEN-paravirt: paravirt: reserve fixmap slot Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 06/20] XEN-paravirt: remove pgd ctor Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 07/20] XEN-paravirt: paravirt shared kernel pmd flag Jeremy Fitzhardinge
2007-01-15  8:59   ` [Xen-devel] " Jan Beulich
2007-01-13  1:45 ` [patch 08/20] XEN-paravirt: paravirt pgd allocation alignment Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 09/20] XEN-paravirt: dont export paravirt_ops structure, do individual functions Jeremy Fitzhardinge
2007-01-14  0:57   ` Rusty Russell
2007-01-13  1:45 ` [patch 10/20] XEN-paravirt: mm lifetime hooks Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 11/20] XEN-paravirt: Add apply_to_page_range() which applies a function to a pte range Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 12/20] XEN-paravirt: Xen: Add nosegneg capability to the vsyscall page notes Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 13/20] XEN-paravirt: Xen: Add config options and disable unsupported config options Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 15/20] XEN-paravirt: Xen: core paravirt guest changes Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 16/20] XEN-paravirt: Add the Xen virtual console driver Jeremy Fitzhardinge
2007-01-14  0:37   ` Alan
2007-01-14  0:35     ` Jeremy Fitzhardinge
2007-01-15 13:03   ` Pavel Machek
2007-01-19  4:11     ` Jeremy Fitzhardinge
2007-01-13  1:45 ` [patch 17/20] XEN-paravirt: Add Xen grant table support Jeremy Fitzhardinge
2007-01-15 13:05   ` Pavel Machek
2007-01-19  4:07     ` Jeremy Fitzhardinge
2007-01-13  1:45 ` Jeremy Fitzhardinge [this message]
2007-01-14  7:41   ` [patch 18/20] XEN-paravirt: Add Xen driver utility functions Greg KH
2007-01-13  1:45 ` [patch 19/20] XEN-paravirt: Add the Xenbus sysfs and virtual device hotplug driver Jeremy Fitzhardinge
2007-01-15 13:18   ` Pavel Machek
2007-01-13  1:45 ` [patch 20/20] XEN-paravirt: Add Xen virtual block device driver Jeremy Fitzhardinge
2007-01-14  1:07   ` Arjan van de Ven
2007-01-14  7:43     ` Greg KH
2007-01-16  2:53     ` [Xen-devel] " Mark Williamson
2007-01-14 11:05   ` Jan Engelhardt
2007-01-14 11:24     ` Muli Ben-Yehuda
2007-01-14 11:35       ` Jan Engelhardt
2007-01-14 12:37     ` Keir Fraser

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