xenbus: Support HVM backends

Add HVM implementations of xenbus_(map,unmap)_ring_v(alloc,free) so
that ring mappings can be done without using GNTMAP_contains_pte which
is not supported on HVM.  This also removes the need to use vmlist_lock
on PV by tracking the allocated xenbus rings.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
[v1: Fix compile error when XENBUS_FRONTEND is defined as module]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Daniel De Graaf 2011-12-19 14:55:14 -05:00 committed by Konrad Rzeszutek Wilk
parent cb85f123cd
commit 2c5d37d30f
3 changed files with 160 additions and 22 deletions

View File

@ -32,15 +32,39 @@
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#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/balloon.h>
#include <xen/events.h>
#include <xen/grant_table.h>
#include <xen/xenbus.h>
#include <xen/xen.h>
#include "xenbus_probe.h"
struct xenbus_map_node {
struct list_head next;
union {
struct vm_struct *area; /* PV */
struct page *page; /* HVM */
};
grant_handle_t handle;
};
static DEFINE_SPINLOCK(xenbus_valloc_lock);
static LIST_HEAD(xenbus_valloc_pages);
struct xenbus_ring_ops {
int (*map)(struct xenbus_device *dev, int gnt, void **vaddr);
int (*unmap)(struct xenbus_device *dev, void *vaddr);
};
static const struct xenbus_ring_ops *ring_ops __read_mostly;
const char *xenbus_strstate(enum xenbus_state state)
{
@ -435,21 +459,35 @@ EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
* XenbusStateClosing and the error message will be saved in XenStore.
*/
int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void **vaddr)
{
return ring_ops->map(dev, gnt_ref, vaddr);
}
EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc);
static int xenbus_map_ring_valloc_pv(struct xenbus_device *dev,
int gnt_ref, void **vaddr)
{
struct gnttab_map_grant_ref op = {
.flags = GNTMAP_host_map | GNTMAP_contains_pte,
.ref = gnt_ref,
.dom = dev->otherend_id,
};
struct xenbus_map_node *node;
struct vm_struct *area;
pte_t *pte;
*vaddr = NULL;
area = alloc_vm_area(PAGE_SIZE, &pte);
if (!area)
node = kzalloc(sizeof(*node), GFP_KERNEL);
if (!node)
return -ENOMEM;
area = alloc_vm_area(PAGE_SIZE, &pte);
if (!area) {
kfree(node);
return -ENOMEM;
}
op.host_addr = arbitrary_virt_to_machine(pte).maddr;
if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
@ -457,19 +495,59 @@ int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void **vaddr)
if (op.status != GNTST_okay) {
free_vm_area(area);
kfree(node);
xenbus_dev_fatal(dev, op.status,
"mapping in shared page %d from domain %d",
gnt_ref, dev->otherend_id);
return op.status;
}
/* Stuff the handle in an unused field */
area->phys_addr = (unsigned long)op.handle;
node->handle = op.handle;
node->area = area;
spin_lock(&xenbus_valloc_lock);
list_add(&node->next, &xenbus_valloc_pages);
spin_unlock(&xenbus_valloc_lock);
*vaddr = area->addr;
return 0;
}
EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc);
static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev,
int gnt_ref, void **vaddr)
{
struct xenbus_map_node *node;
int err;
void *addr;
*vaddr = NULL;
node = kzalloc(sizeof(*node), GFP_KERNEL);
if (!node)
return -ENOMEM;
err = alloc_xenballooned_pages(1, &node->page, false /* lowmem */);
if (err)
goto out_err;
addr = pfn_to_kaddr(page_to_pfn(node->page));
err = xenbus_map_ring(dev, gnt_ref, &node->handle, addr);
if (err)
goto out_err;
spin_lock(&xenbus_valloc_lock);
list_add(&node->next, &xenbus_valloc_pages);
spin_unlock(&xenbus_valloc_lock);
*vaddr = addr;
return 0;
out_err:
free_xenballooned_pages(1, &node->page);
kfree(node);
return err;
}
/**
@ -525,32 +603,36 @@ EXPORT_SYMBOL_GPL(xenbus_map_ring);
*/
int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
{
struct vm_struct *area;
return ring_ops->unmap(dev, vaddr);
}
EXPORT_SYMBOL_GPL(xenbus_unmap_ring_vfree);
static int xenbus_unmap_ring_vfree_pv(struct xenbus_device *dev, void *vaddr)
{
struct xenbus_map_node *node;
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.
* We could force the user to hang on to their struct vm_struct from
* xenbus_map_ring_valloc, but these 6 lines considerably simplify
* this API.
*/
read_lock(&vmlist_lock);
for (area = vmlist; area != NULL; area = area->next) {
if (area->addr == vaddr)
break;
spin_lock(&xenbus_valloc_lock);
list_for_each_entry(node, &xenbus_valloc_pages, next) {
if (node->area->addr == vaddr) {
list_del(&node->next);
goto found;
}
}
read_unlock(&vmlist_lock);
node = NULL;
found:
spin_unlock(&xenbus_valloc_lock);
if (!area) {
if (!node) {
xenbus_dev_error(dev, -ENOENT,
"can't find mapped virtual address %p", vaddr);
return GNTST_bad_virt_addr;
}
op.handle = (grant_handle_t)area->phys_addr;
op.handle = node->handle;
op.host_addr = arbitrary_virt_to_machine(
lookup_address((unsigned long)vaddr, &level)).maddr;
@ -558,16 +640,50 @@ int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
BUG();
if (op.status == GNTST_okay)
free_vm_area(area);
free_vm_area(node->area);
else
xenbus_dev_error(dev, op.status,
"unmapping page at handle %d error %d",
(int16_t)area->phys_addr, op.status);
node->handle, op.status);
kfree(node);
return op.status;
}
EXPORT_SYMBOL_GPL(xenbus_unmap_ring_vfree);
static int xenbus_unmap_ring_vfree_hvm(struct xenbus_device *dev, void *vaddr)
{
int rv;
struct xenbus_map_node *node;
void *addr;
spin_lock(&xenbus_valloc_lock);
list_for_each_entry(node, &xenbus_valloc_pages, next) {
addr = pfn_to_kaddr(page_to_pfn(node->page));
if (addr == vaddr) {
list_del(&node->next);
goto found;
}
}
node = NULL;
found:
spin_unlock(&xenbus_valloc_lock);
if (!node) {
xenbus_dev_error(dev, -ENOENT,
"can't find mapped virtual address %p", vaddr);
return GNTST_bad_virt_addr;
}
rv = xenbus_unmap_ring(dev, node->handle, addr);
if (!rv)
free_xenballooned_pages(1, &node->page);
else
WARN(1, "Leaking %p\n", vaddr);
kfree(node);
return rv;
}
/**
* xenbus_unmap_ring
@ -617,3 +733,21 @@ enum xenbus_state xenbus_read_driver_state(const char *path)
return result;
}
EXPORT_SYMBOL_GPL(xenbus_read_driver_state);
static const struct xenbus_ring_ops ring_ops_pv = {
.map = xenbus_map_ring_valloc_pv,
.unmap = xenbus_unmap_ring_vfree_pv,
};
static const struct xenbus_ring_ops ring_ops_hvm = {
.map = xenbus_map_ring_valloc_hvm,
.unmap = xenbus_unmap_ring_vfree_hvm,
};
void __init xenbus_ring_ops_init(void)
{
if (xen_pv_domain())
ring_ops = &ring_ops_pv;
else
ring_ops = &ring_ops_hvm;
}

View File

@ -730,6 +730,8 @@ static int __init xenbus_init(void)
if (!xen_domain())
return -ENODEV;
xenbus_ring_ops_init();
if (xen_hvm_domain()) {
uint64_t v = 0;
err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);

View File

@ -76,4 +76,6 @@ extern void xenbus_otherend_changed(struct xenbus_watch *watch,
extern int xenbus_read_otherend_details(struct xenbus_device *xendev,
char *id_node, char *path_node);
void xenbus_ring_ops_init(void);
#endif