xen/grant: Implement an grant frame array struct (v3).

The 'xen_hvm_resume_frames' used to be an 'unsigned long'
and contain the virtual address of the grants. That was OK
for most architectures (PVHVM, ARM) were the grants are contiguous
in memory. That however is not the case for PVH - in which case
we will have to do a lookup for each virtual address for the PFN.

Instead of doing that, lets make it a structure which will contain
the array of PFNs, the virtual address and the count of said PFNs.

Also provide a generic functions: gnttab_setup_auto_xlat_frames and
gnttab_free_auto_xlat_frames to populate said structure with
appropriate values for PVHVM and ARM.

To round it off, change the name from 'xen_hvm_resume_frames' to
a more descriptive one - 'xen_auto_xlat_grant_frames'.

For PVH, in patch "xen/pvh: Piggyback on PVHVM for grant driver"
we will populate the 'xen_auto_xlat_grant_frames' by ourselves.

v2 moves the xen_remap in the gnttab_setup_auto_xlat_frames
and also introduces xen_unmap for gnttab_free_auto_xlat_frames.

Suggested-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[v3: Based on top of 'asm/xen/page.h: remove redundant semicolon']
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

2 files changed, 8 insertions, 2 deletions

diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h
index ac6789aad059..709c4b4d2f1d 100644
--- a/arch/arm/include/asm/xen/page.h
+++ b/arch/arm/include/asm/xen/page.h
@@ -118,5 +118,6 @@ static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 }
 
 #define xen_remap(cookie, size) ioremap_cached((cookie), (size))
+#define xen_unmap(cookie) iounmap((cookie))
 
 #endif /* _ASM_ARM_XEN_PAGE_H */
diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 85501238b425..2162172c0ddc 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -208,6 +208,7 @@ static int __init xen_guest_init(void)
         const char *version = NULL;
         const char *xen_prefix = "xen,xen-";
         struct resource res;
+        unsigned long grant_frames;
 
         node = of_find_compatible_node(NULL, NULL, "xen,xen");
         if (!node) {
@@ -224,10 +225,10 @@ static int __init xen_guest_init(void)
         }
         if (of_address_to_resource(node, GRANT_TABLE_PHYSADDR, &res))
                 return 0;
-        xen_hvm_resume_frames = res.start;
+        grant_frames = res.start;
         xen_events_irq = irq_of_parse_and_map(node, 0);
         pr_info("Xen %s support found, events_irq=%d gnttab_frame_pfn=%lx\n",
-                        version, xen_events_irq, (xen_hvm_resume_frames >> PAGE_SHIFT));
+                        version, xen_events_irq, (grant_frames >> PAGE_SHIFT));
         xen_domain_type = XEN_HVM_DOMAIN;
 
         xen_setup_features();
@@ -265,6 +266,10 @@ static int __init xen_guest_init(void)
         if (xen_vcpu_info == NULL)
                 return -ENOMEM;
 
+        if (gnttab_setup_auto_xlat_frames(grant_frames)) {
+                free_percpu(xen_vcpu_info);
+                return -ENOMEM;
+        }
         gnttab_init();
         if (!xen_initial_domain())
                 xenbus_probe(NULL);