xen: Use correctly the Xen memory terminologies

Based on include/xen/mm.h [1], Linux is mistakenly using MFN when GFN
is meant, I suspect this is because the first support for Xen was for
PV. This resulted in some misimplementation of helpers on ARM and
confused developers about the expected behavior.

For instance, with pfn_to_mfn, we expect to get an MFN based on the name.
Although, if we look at the implementation on x86, it's returning a GFN.

For clarity and avoid new confusion, replace any reference to mfn with
gfn in any helpers used by PV drivers. The x86 code will still keep some
reference of pfn_to_mfn which may be used by all kind of guests
No changes as been made in the hypercall field, even
though they may be invalid, in order to keep the same as the defintion
in xen repo.

Note that page_to_mfn has been renamed to xen_page_to_gfn to avoid a
name to close to the KVM function gfn_to_page.

Take also the opportunity to simplify simple construction such
as pfn_to_mfn(page_to_pfn(page)) into xen_page_to_gfn. More complex clean up
will come in follow-up patches.

[1] http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=e758ed14f390342513405dd766e874934573e6cb

Signed-off-by: Julien Grall <julien.grall@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

9 files changed, 14 insertions, 15 deletions

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 1fa633b2d556..c79329fcfa78 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -441,7 +441,7 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 	/* Update direct mapping, invalidate P2M, and add to balloon. */
 	for (i = 0; i < nr_pages; i++) {
 		pfn = frame_list[i];
-		frame_list[i] = pfn_to_mfn(pfn);
+		frame_list[i] = pfn_to_gfn(pfn);
 		page = pfn_to_page(pfn);
 
 #ifdef CONFIG_XEN_HAVE_PVMMU
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index ed620e5857a1..c49bb7a5be8f 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1688,7 +1688,7 @@ void __init xen_init_IRQ(void)
 		struct physdev_pirq_eoi_gmfn eoi_gmfn;
 
 		pirq_eoi_map = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
-		eoi_gmfn.gmfn = virt_to_mfn(pirq_eoi_map);
+		eoi_gmfn.gmfn = virt_to_gfn(pirq_eoi_map);
 		rc = HYPERVISOR_physdev_op(PHYSDEVOP_pirq_eoi_gmfn_v2, &eoi_gmfn);
 		/* TODO: No PVH support for PIRQ EOI */
 		if (rc != 0) {
diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c
index ed673e1acd61..1d4baf56c36b 100644
--- a/drivers/xen/events/events_fifo.c
+++ b/drivers/xen/events/events_fifo.c
@@ -111,7 +111,7 @@ static int init_control_block(int cpu,
 	for (i = 0; i < EVTCHN_FIFO_MAX_QUEUES; i++)
 		q->head[i] = 0;
 
-	init_control.control_gfn = virt_to_mfn(control_block);
+	init_control.control_gfn = virt_to_gfn(control_block);
 	init_control.offset      = 0;
 	init_control.vcpu        = cpu;
 
@@ -167,7 +167,7 @@ static int evtchn_fifo_setup(struct irq_info *info)
 		/* Mask all events in this page before adding it. */
 		init_array_page(array_page);
 
-		expand_array.array_gfn = virt_to_mfn(array_page);
+		expand_array.array_gfn = virt_to_gfn(array_page);
 
 		ret = HYPERVISOR_event_channel_op(EVTCHNOP_expand_array, &expand_array);
 		if (ret < 0)
diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c
index e53fe191738c..14370df9ac1c 100644
--- a/drivers/xen/gntalloc.c
+++ b/drivers/xen/gntalloc.c
@@ -142,7 +142,8 @@ static int add_grefs(struct ioctl_gntalloc_alloc_gref *op,
 
 		/* Grant foreign access to the page. */
 		rc = gnttab_grant_foreign_access(op->domid,
-			pfn_to_mfn(page_to_pfn(gref->page)), readonly);
+						 xen_page_to_gfn(gref->page),
+						 readonly);
 		if (rc < 0)
 			goto undo;
 		gref_ids[i] = gref->gref_id = rc;
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index d10effee9b9e..e12bd3635f83 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -80,7 +80,7 @@ static int xen_suspend(void *data)
 	 * is resuming in a new domain.
 	 */
 	si->cancelled = HYPERVISOR_suspend(xen_pv_domain()
-                                           ? virt_to_mfn(xen_start_info)
+                                           ? virt_to_gfn(xen_start_info)
                                            : 0);
 
 	xen_arch_post_suspend(si->cancelled);
diff --git a/drivers/xen/tmem.c b/drivers/xen/tmem.c
index 239738f944ba..28c97ff606f4 100644
--- a/drivers/xen/tmem.c
+++ b/drivers/xen/tmem.c
@@ -131,7 +131,7 @@ static int xen_tmem_new_pool(struct tmem_pool_uuid uuid,
 static int xen_tmem_put_page(u32 pool_id, struct tmem_oid oid,
 			     u32 index, unsigned long pfn)
 {
-	unsigned long gmfn = xen_pv_domain() ? pfn_to_mfn(pfn) : pfn;
+	unsigned long gmfn = pfn_to_gfn(pfn);
 
 	return xen_tmem_op(TMEM_PUT_PAGE, pool_id, oid, index,
 		gmfn, 0, 0, 0);
@@ -140,7 +140,7 @@ static int xen_tmem_put_page(u32 pool_id, struct tmem_oid oid,
 static int xen_tmem_get_page(u32 pool_id, struct tmem_oid oid,
 			     u32 index, unsigned long pfn)
 {
-	unsigned long gmfn = xen_pv_domain() ? pfn_to_mfn(pfn) : pfn;
+	unsigned long gmfn = pfn_to_gfn(pfn);
 
 	return xen_tmem_op(TMEM_GET_PAGE, pool_id, oid, index,
 		gmfn, 0, 0, 0);
diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index e30353575d5d..2ba09c1195c8 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -380,7 +380,7 @@ int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr,
 
 	for (i = 0; i < nr_pages; i++) {
 		err = gnttab_grant_foreign_access(dev->otherend_id,
-						  virt_to_mfn(vaddr), 0);
+						  virt_to_gfn(vaddr), 0);
 		if (err < 0) {
 			xenbus_dev_fatal(dev, err,
 					 "granting access to ring page");
diff --git a/drivers/xen/xenbus/xenbus_dev_backend.c b/drivers/xen/xenbus/xenbus_dev_backend.c
index b17707ee07d4..ee6d9efd7b76 100644
--- a/drivers/xen/xenbus/xenbus_dev_backend.c
+++ b/drivers/xen/xenbus/xenbus_dev_backend.c
@@ -49,7 +49,7 @@ static long xenbus_alloc(domid_t domid)
 		goto out_err;
 
 	gnttab_grant_foreign_access_ref(GNTTAB_RESERVED_XENSTORE, domid,
-			virt_to_mfn(xen_store_interface), 0 /* writable */);
+			virt_to_gfn(xen_store_interface), 0 /* writable */);
 
 	arg.dom = DOMID_SELF;
 	arg.remote_dom = domid;
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index 4308fb3cf7c2..b3870f4ca1d0 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -711,9 +711,7 @@ static int __init xenstored_local_init(void)
 	if (!page)
 		goto out_err;
 
-	xen_store_mfn = xen_start_info->store_mfn =
-		pfn_to_mfn(virt_to_phys((void *)page) >>
-			   PAGE_SHIFT);
+	xen_store_mfn = xen_start_info->store_mfn = virt_to_gfn((void *)page);
 
 	/* Next allocate a local port which xenstored can bind to */
 	alloc_unbound.dom        = DOMID_SELF;
@@ -787,12 +785,12 @@ static int __init xenbus_init(void)
 		err = xenstored_local_init();
 		if (err)
 			goto out_error;
-		xen_store_interface = mfn_to_virt(xen_store_mfn);
+		xen_store_interface = gfn_to_virt(xen_store_mfn);
 		break;
 	case XS_PV:
 		xen_store_evtchn = xen_start_info->store_evtchn;
 		xen_store_mfn = xen_start_info->store_mfn;
-		xen_store_interface = mfn_to_virt(xen_store_mfn);
+		xen_store_interface = gfn_to_virt(xen_store_mfn);
 		break;
 	case XS_HVM:
 		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);