> > >
> > > oookay, I queued this for 3.1 and tagged it for a 3.0.x backport. I
> > > *think* that's the outcome of this discussion, for the short-term?
> >
> > <nods> Yup. Thanks!
>
> Hey Andrew,
>
> The long term outcome is the patchset that David worked on. I've sent
> a GIT PULL to Linus to pick up the Xen related patches that switch over
> the users of the right API:
>
> (xen) stable/vmalloc-3.2 for Linux 3.2-rc0
>
> (https://lkml.org/lkml/2011/10/29/82)
And Linus picked it up.
.. snip..
>
> Also, not sure what you thought of this patch below?
Patch included as attachment for easier review..
>
> From b9acd3abc12972be0d938d7bc2466d899023e757 Mon Sep 17 00:00:00 2001
> From: David Vrabel <david.vrabel@xxxxxxxxxx>
> Date: Thu, 29 Sep 2011 16:53:32 +0100
> Subject: [PATCH] xen: map foreign pages for shared rings by updating the PTEs
> directly
>
> When mapping a foreign page with xenbus_map_ring_valloc() with the
> GNTTABOP_map_grant_ref hypercall, set the GNTMAP_contains_pte flag and
> pass a pointer to the PTE (in init_mm).
>
> After the page is mapped, the usual fault mechanism can be used to
> update additional MMs. This allows the vmalloc_sync_all() to be
> removed from alloc_vm_area().
>
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
> arch/x86/xen/grant-table.c | 2 +-
> drivers/xen/xenbus/xenbus_client.c | 11 ++++++++---
> include/linux/vmalloc.h | 2 +-
> mm/vmalloc.c | 27 +++++++++++++--------------
> 4 files changed, 23 insertions(+), 19 deletions(-)
>
> diff --git a/arch/x86/xen/grant-table.c b/arch/x86/xen/grant-table.c
> index 6bbfd7a..5a40d24 100644
> --- a/arch/x86/xen/grant-table.c
> +++ b/arch/x86/xen/grant-table.c
> @@ -71,7 +71,7 @@ int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
>
> if (shared == NULL) {
> struct vm_struct *area =
> - alloc_vm_area(PAGE_SIZE * max_nr_gframes);
> + alloc_vm_area(PAGE_SIZE * max_nr_gframes, NULL);
> BUG_ON(area == NULL);
> shared = area->addr;
> *__shared = shared;
> diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
> index 229d3ad..52bc57f 100644
> --- a/drivers/xen/xenbus/xenbus_client.c
> +++ b/drivers/xen/xenbus/xenbus_client.c
> @@ -34,6 +34,7 @@
> #include <linux/types.h>
> #include <linux/vmalloc.h>
> #include <asm/xen/hypervisor.h>
> +#include <asm/xen/page.h>
> #include <xen/interface/xen.h>
> #include <xen/interface/event_channel.h>
> #include <xen/events.h>
> @@ -435,19 +436,20 @@ EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
> int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void **vaddr)
> {
> struct gnttab_map_grant_ref op = {
> - .flags = GNTMAP_host_map,
> + .flags = GNTMAP_host_map | GNTMAP_contains_pte,
> .ref = gnt_ref,
> .dom = dev->otherend_id,
> };
> struct vm_struct *area;
> + pte_t *pte;
>
> *vaddr = NULL;
>
> - area = alloc_vm_area(PAGE_SIZE);
> + area = alloc_vm_area(PAGE_SIZE, &pte);
> if (!area)
> return -ENOMEM;
>
> - op.host_addr = (unsigned long)area->addr;
> + op.host_addr = arbitrary_virt_to_machine(pte).maddr;
>
> if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
> BUG();
> @@ -526,6 +528,7 @@ int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
> struct gnttab_unmap_grant_ref op = {
> .host_addr = (unsigned long)vaddr,
> };
> + unsigned int level;
>
> /* It'd be nice if linux/vmalloc.h provided a find_vm_area(void *addr)
> * method so that we don't have to muck with vmalloc internals here.
> @@ -547,6 +550,8 @@ int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
> }
>
> op.handle = (grant_handle_t)area->phys_addr;
> + op.host_addr = arbitrary_virt_to_machine(
> + lookup_address((unsigned long)vaddr, &level)).maddr;
>
> if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
> BUG();
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 9332e52..1a77252 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -118,7 +118,7 @@ unmap_kernel_range(unsigned long addr, unsigned long size)
> #endif
>
> /* Allocate/destroy a 'vmalloc' VM area. */
> -extern struct vm_struct *alloc_vm_area(size_t size);
> +extern struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes);
> extern void free_vm_area(struct vm_struct *area);
>
> /* for /dev/kmem */
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 5016f19..b5deec6 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -2105,23 +2105,30 @@ void __attribute__((weak)) vmalloc_sync_all(void)
>
> static int f(pte_t *pte, pgtable_t table, unsigned long addr, void *data)
> {
> - /* apply_to_page_range() does all the hard work. */
> + pte_t ***p = data;
> +
> + if (p) {
> + *(*p) = pte;
> + (*p)++;
> + }
> return 0;
> }
>
> /**
> * alloc_vm_area - allocate a range of kernel address space
> * @size: size of the area
> + * @ptes: returns the PTEs for the address space
> *
> * Returns: NULL on failure, vm_struct on success
> *
> * This function reserves a range of kernel address space, and
> * allocates pagetables to map that range. No actual mappings
> - * are created. If the kernel address space is not shared
> - * between processes, it syncs the pagetable across all
> - * processes.
> + * are created.
> + *
> + * If @ptes is non-NULL, pointers to the PTEs (in init_mm)
> + * allocated for the VM area are returned.
> */
> -struct vm_struct *alloc_vm_area(size_t size)
> +struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
> {
> struct vm_struct *area;
>
> @@ -2135,19 +2142,11 @@ struct vm_struct *alloc_vm_area(size_t size)
> * 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)) {
> + size, f, ptes ? &ptes : NULL)) {
> free_vm_area(area);
> return NULL;
> }
>
> - /*
> - * If the allocated address space is passed to a hypercall
> - * before being used then we cannot rely on a page fault to
> - * trigger an update of the page tables. So sync all the page
> - * tables here.
> - */
> - vmalloc_sync_all();
> -
> return area;
> }
> EXPORT_SYMBOL_GPL(alloc_vm_area);
> --
> 1.7.7.1
>
>From 21396dbbb3f976c8b4deb9f696994458dbe00db0 Mon Sep 17 00:00:00 2001
From: David Vrabel <david.vrabel@xxxxxxxxxx>
Date: Thu, 29 Sep 2011 16:53:32 +0100
Subject: [PATCH] xen: map foreign pages for shared rings by updating the PTEs
directly
When mapping a foreign page with xenbus_map_ring_valloc() with the
GNTTABOP_map_grant_ref hypercall, set the GNTMAP_contains_pte flag and
pass a pointer to the PTE (in init_mm).
After the page is mapped, the usual fault mechanism can be used to
update additional MMs. This allows the vmalloc_sync_all() to be
removed from alloc_vm_area().
Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
arch/x86/xen/grant-table.c | 2 +-
drivers/xen/xenbus/xenbus_client.c | 11 ++++++++---
include/linux/vmalloc.h | 2 +-
mm/vmalloc.c | 27 +++++++++++++--------------
4 files changed, 23 insertions(+), 19 deletions(-)
diff --git a/arch/x86/xen/grant-table.c b/arch/x86/xen/grant-table.c
index 6bbfd7a..5a40d24 100644
--- a/arch/x86/xen/grant-table.c
+++ b/arch/x86/xen/grant-table.c
@@ -71,7 +71,7 @@ int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
if (shared == NULL) {
struct vm_struct *area =
- alloc_vm_area(PAGE_SIZE * max_nr_gframes);
+ alloc_vm_area(PAGE_SIZE * max_nr_gframes, NULL);
BUG_ON(area == NULL);
shared = area->addr;
*__shared = shared;
diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index 81c3ce6..1906125 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -35,6 +35,7 @@
#include <linux/vmalloc.h>
#include <linux/export.h>
#include <asm/xen/hypervisor.h>
+#include <asm/xen/page.h>
#include <xen/interface/xen.h>
#include <xen/interface/event_channel.h>
#include <xen/events.h>
@@ -436,19 +437,20 @@ EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void **vaddr)
{
struct gnttab_map_grant_ref op = {
- .flags = GNTMAP_host_map,
+ .flags = GNTMAP_host_map | GNTMAP_contains_pte,
.ref = gnt_ref,
.dom = dev->otherend_id,
};
struct vm_struct *area;
+ pte_t *pte;
*vaddr = NULL;
- area = alloc_vm_area(PAGE_SIZE);
+ area = alloc_vm_area(PAGE_SIZE, &pte);
if (!area)
return -ENOMEM;
- op.host_addr = (unsigned long)area->addr;
+ op.host_addr = arbitrary_virt_to_machine(pte).maddr;
if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
BUG();
@@ -527,6 +529,7 @@ int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
struct gnttab_unmap_grant_ref op = {
.host_addr = (unsigned long)vaddr,
};
+ unsigned int level;
/* It'd be nice if linux/vmalloc.h provided a find_vm_area(void *addr)
* method so that we don't have to muck with vmalloc internals here.
@@ -548,6 +551,8 @@ int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
}
op.handle = (grant_handle_t)area->phys_addr;
+ op.host_addr = arbitrary_virt_to_machine(
+ lookup_address((unsigned long)vaddr, &level)).maddr;
if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
BUG();
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 687fb11..4bde182 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -119,7 +119,7 @@ unmap_kernel_range(unsigned long addr, unsigned long size)
#endif
/* Allocate/destroy a 'vmalloc' VM area. */
-extern struct vm_struct *alloc_vm_area(size_t size);
+extern struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes);
extern void free_vm_area(struct vm_struct *area);
/* for /dev/kmem */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index b669aa6..3231bf3 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2141,23 +2141,30 @@ void __attribute__((weak)) vmalloc_sync_all(void)
static int f(pte_t *pte, pgtable_t table, unsigned long addr, void *data)
{
- /* apply_to_page_range() does all the hard work. */
+ pte_t ***p = data;
+
+ if (p) {
+ *(*p) = pte;
+ (*p)++;
+ }
return 0;
}
/**
* alloc_vm_area - allocate a range of kernel address space
* @size: size of the area
+ * @ptes: returns the PTEs for the address space
*
* Returns: NULL on failure, vm_struct on success
*
* This function reserves a range of kernel address space, and
* allocates pagetables to map that range. No actual mappings
- * are created. If the kernel address space is not shared
- * between processes, it syncs the pagetable across all
- * processes.
+ * are created.
+ *
+ * If @ptes is non-NULL, pointers to the PTEs (in init_mm)
+ * allocated for the VM area are returned.
*/
-struct vm_struct *alloc_vm_area(size_t size)
+struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
{
struct vm_struct *area;
@@ -2171,19 +2178,11 @@ struct vm_struct *alloc_vm_area(size_t size)
* 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)) {
+ size, f, ptes ? &ptes : NULL)) {
free_vm_area(area);
return NULL;
}
- /*
- * If the allocated address space is passed to a hypercall
- * before being used then we cannot rely on a page fault to
- * trigger an update of the page tables. So sync all the page
- * tables here.
- */
- vmalloc_sync_all();
-
return area;
}
EXPORT_SYMBOL_GPL(alloc_vm_area);
--
1.7.7.1