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Date: Fri, 8 Aug 2014 13:37:18 -0700
From: Kamal Mostafa <kamal@...onical.com>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
kernel-team@...ts.ubuntu.com
Cc: David Vrabel <david.vrabel@...rix.com>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
Stefan Bader <stefan.bader@...onical.com>,
Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.13 015/259] x86/xen: safely map and unmap grant frames when in atomic context
3.13.11.6 -stable review patch. If anyone has any objections, please let me know.
------------------
From: David Vrabel <david.vrabel@...rix.com>
commit b7dd0e350e0bd4c0fddcc9b8958342700b00b168 upstream.
arch_gnttab_map_frames() and arch_gnttab_unmap_frames() are called in
atomic context but were calling alloc_vm_area() which might sleep.
Also, if a driver attempts to allocate a grant ref from an interrupt
and the table needs expanding, then the CPU may already by in lazy MMU
mode and apply_to_page_range() will BUG when it tries to re-enable
lazy MMU mode.
These two functions are only used in PV guests.
Introduce arch_gnttab_init() to allocates the virtual address space in
advance.
Avoid the use of apply_to_page_range() by using saving and using the
array of PTE addresses from the alloc_vm_area() call (which ensures
that the required page tables are pre-allocated).
Signed-off-by: David Vrabel <david.vrabel@...rix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
[ David Vrabel: Backported to 3.13.10. ]
Signed-off-by: David Vrabel <david.vrabel@...rix.com>
Cc: Stefan Bader <stefan.bader@...onical.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
arch/arm/xen/grant-table.c | 5 ++
arch/x86/xen/grant-table.c | 148 ++++++++++++++++++++++++++++-----------------
drivers/xen/grant-table.c | 5 ++
include/xen/grant_table.h | 1 +
4 files changed, 102 insertions(+), 57 deletions(-)
diff --git a/arch/arm/xen/grant-table.c b/arch/arm/xen/grant-table.c
index 859a9bb..91cf08b 100644
--- a/arch/arm/xen/grant-table.c
+++ b/arch/arm/xen/grant-table.c
@@ -51,3 +51,8 @@ int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
{
return -ENOSYS;
}
+
+int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status)
+{
+ return 0;
+}
diff --git a/arch/x86/xen/grant-table.c b/arch/x86/xen/grant-table.c
index 3a5f55d..4d2c9bf 100644
--- a/arch/x86/xen/grant-table.c
+++ b/arch/x86/xen/grant-table.c
@@ -36,92 +36,126 @@
#include <linux/sched.h>
#include <linux/mm.h>
+#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <xen/interface/xen.h>
#include <xen/page.h>
#include <xen/grant_table.h>
+#include <xen/xen.h>
#include <asm/pgtable.h>
-static int map_pte_fn(pte_t *pte, struct page *pmd_page,
- unsigned long addr, void *data)
-{
- unsigned long **frames = (unsigned long **)data;
-
- set_pte_at(&init_mm, addr, pte, mfn_pte((*frames)[0], PAGE_KERNEL));
- (*frames)++;
- return 0;
-}
-
-/*
- * This function is used to map shared frames to store grant status. It is
- * different from map_pte_fn above, the frames type here is uint64_t.
- */
-static int map_pte_fn_status(pte_t *pte, struct page *pmd_page,
- unsigned long addr, void *data)
-{
- uint64_t **frames = (uint64_t **)data;
-
- set_pte_at(&init_mm, addr, pte, mfn_pte((*frames)[0], PAGE_KERNEL));
- (*frames)++;
- return 0;
-}
-
-static int unmap_pte_fn(pte_t *pte, struct page *pmd_page,
- unsigned long addr, void *data)
-{
-
- set_pte_at(&init_mm, addr, pte, __pte(0));
- return 0;
-}
+static struct gnttab_vm_area {
+ struct vm_struct *area;
+ pte_t **ptes;
+} gnttab_shared_vm_area, gnttab_status_vm_area;
int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
unsigned long max_nr_gframes,
void **__shared)
{
- int rc;
void *shared = *__shared;
+ unsigned long addr;
+ unsigned long i;
+
+ if (shared == NULL)
+ *__shared = shared = gnttab_shared_vm_area.area->addr;
- if (shared == NULL) {
- struct vm_struct *area =
- alloc_vm_area(PAGE_SIZE * max_nr_gframes, NULL);
- BUG_ON(area == NULL);
- shared = area->addr;
- *__shared = shared;
+ addr = (unsigned long)shared;
+
+ for (i = 0; i < nr_gframes; i++) {
+ set_pte_at(&init_mm, addr, gnttab_shared_vm_area.ptes[i],
+ mfn_pte(frames[i], PAGE_KERNEL));
+ addr += PAGE_SIZE;
}
- rc = apply_to_page_range(&init_mm, (unsigned long)shared,
- PAGE_SIZE * nr_gframes,
- map_pte_fn, &frames);
- return rc;
+ return 0;
}
int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
unsigned long max_nr_gframes,
grant_status_t **__shared)
{
- int rc;
grant_status_t *shared = *__shared;
+ unsigned long addr;
+ unsigned long i;
+
+ if (shared == NULL)
+ *__shared = shared = gnttab_status_vm_area.area->addr;
- if (shared == NULL) {
- /* No need to pass in PTE as we are going to do it
- * in apply_to_page_range anyhow. */
- struct vm_struct *area =
- alloc_vm_area(PAGE_SIZE * max_nr_gframes, NULL);
- BUG_ON(area == NULL);
- shared = area->addr;
- *__shared = shared;
+ addr = (unsigned long)shared;
+
+ for (i = 0; i < nr_gframes; i++) {
+ set_pte_at(&init_mm, addr, gnttab_status_vm_area.ptes[i],
+ mfn_pte(frames[i], PAGE_KERNEL));
+ addr += PAGE_SIZE;
}
- rc = apply_to_page_range(&init_mm, (unsigned long)shared,
- PAGE_SIZE * nr_gframes,
- map_pte_fn_status, &frames);
- return rc;
+ return 0;
}
void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
{
- apply_to_page_range(&init_mm, (unsigned long)shared,
- PAGE_SIZE * nr_gframes, unmap_pte_fn, NULL);
+ pte_t **ptes;
+ unsigned long addr;
+ unsigned long i;
+
+ if (shared == gnttab_status_vm_area.area->addr)
+ ptes = gnttab_status_vm_area.ptes;
+ else
+ ptes = gnttab_shared_vm_area.ptes;
+
+ addr = (unsigned long)shared;
+
+ for (i = 0; i < nr_gframes; i++) {
+ set_pte_at(&init_mm, addr, ptes[i], __pte(0));
+ addr += PAGE_SIZE;
+ }
+}
+
+static int arch_gnttab_valloc(struct gnttab_vm_area *area, unsigned nr_frames)
+{
+ area->ptes = kmalloc(sizeof(pte_t *) * nr_frames, GFP_KERNEL);
+ if (area->ptes == NULL)
+ return -ENOMEM;
+
+ area->area = alloc_vm_area(PAGE_SIZE * nr_frames, area->ptes);
+ if (area->area == NULL) {
+ kfree(area->ptes);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static void arch_gnttab_vfree(struct gnttab_vm_area *area)
+{
+ free_vm_area(area->area);
+ kfree(area->ptes);
+}
+
+int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status)
+{
+ int ret;
+
+ if (!xen_pv_domain())
+ return 0;
+
+ ret = arch_gnttab_valloc(&gnttab_shared_vm_area, nr_shared);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * Always allocate the space for the status frames in case
+ * we're migrated to a host with V2 support.
+ */
+ ret = arch_gnttab_valloc(&gnttab_status_vm_area, nr_status);
+ if (ret < 0)
+ goto err;
+
+ return 0;
+ err:
+ arch_gnttab_vfree(&gnttab_shared_vm_area);
+ return -ENOMEM;
}
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index aa846a4..b983a99 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -1250,6 +1250,11 @@ int gnttab_init(void)
}
}
+ ret = arch_gnttab_init(boot_max_nr_grant_frames,
+ nr_status_frames(boot_max_nr_grant_frames));
+ if (ret < 0)
+ goto ini_nomem;
+
if (gnttab_setup() < 0) {
ret = -ENODEV;
goto ini_nomem;
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index 694dcaf..bbb6c50 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -170,6 +170,7 @@ gnttab_set_unmap_op(struct gnttab_unmap_grant_ref *unmap, phys_addr_t addr,
unmap->dev_bus_addr = 0;
}
+int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status);
int arch_gnttab_map_shared(xen_pfn_t *frames, unsigned long nr_gframes,
unsigned long max_nr_gframes,
void **__shared);
--
1.9.1
--
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