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>

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/xen/platform-pci.c b/drivers/xen/platform-pci.c
index 2f3528e93cb9..f1947ac218d9 100644
--- a/drivers/xen/platform-pci.c
+++ b/drivers/xen/platform-pci.c
@@ -108,6 +108,7 @@ static int platform_pci_init(struct pci_dev *pdev,
         long ioaddr;
         long mmio_addr, mmio_len;
         unsigned int max_nr_gframes;
+        unsigned long grant_frames;
 
         if (!xen_domain())
                 return -ENODEV;
@@ -154,13 +155,16 @@ static int platform_pci_init(struct pci_dev *pdev,
         }
 
         max_nr_gframes = gnttab_max_grant_frames();
-        xen_hvm_resume_frames = alloc_xen_mmio(PAGE_SIZE * max_nr_gframes);
+        grant_frames = alloc_xen_mmio(PAGE_SIZE * max_nr_gframes);
+        if (gnttab_setup_auto_xlat_frames(grant_frames))
+                goto out;
         ret = gnttab_init();
         if (ret)
-                goto out;
+                goto grant_out;
         xenbus_probe(NULL);
         return 0;
-
+grant_out:
+        gnttab_free_auto_xlat_frames();
 out:
         pci_release_region(pdev, 0);
 mem_out: