>From 21396dbbb3f976c8b4deb9f696994458dbe00db0 Mon Sep 17 00:00:00 2001 From: David Vrabel 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 Cc: Andrew Morton Cc: Jeremy Fitzhardinge Signed-off-by: Konrad Rzeszutek Wilk --- 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 #include #include +#include #include #include #include @@ -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