Commit 2c5d37d3 authored by Daniel De Graaf's avatar Daniel De Graaf Committed by Konrad Rzeszutek Wilk
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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: default avatarDaniel De Graaf <dgdegra@tycho.nsa.gov>
[v1: Fix compile error when XENBUS_FRONTEND is defined as module]
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent cb85f123

drivers/xen/xenbus/xenbus_client.c

+155 −21
Original line number Diff line number Diff line
@@ -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)

{
@@ -435,20 +459,34 @@ 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;



	node = kzalloc(sizeof(*node), GFP_KERNEL);

	if (!node)

		return -ENOMEM;



	area = alloc_vm_area(PAGE_SIZE, &pte);

	if (!area)

	if (!area) {

		kfree(node);

		return -ENOMEM;

	}



	op.host_addr = arbitrary_virt_to_machine(pte).maddr;
@@ -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;

}

drivers/xen/xenbus/xenbus_probe.c

+2 −0
Original line number Diff line number Diff line
@@ -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);

drivers/xen/xenbus/xenbus_probe.h

+2 −0
Original line number Diff line number Diff line
@@ -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

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