xen: implement XENMEM_machphys_mapping

This hypercall allows Xen to specify a non-default location for the
machine to physical mapping. This capability is used when running a 32
bit domain 0 on a 64 bit hypervisor to shrink the hypervisor hole to
exactly the size required.

[ Impact: add Xen hypercall definitions ]

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 21ed8d7f75a5..bd2713a82571 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -2034,6 +2034,20 @@ static __init void xen_map_identity_early(pmd_t *pmd, unsigned long max_pfn)
         set_page_prot(pmd, PAGE_KERNEL_RO);
 }
 
+void __init xen_setup_machphys_mapping(void)
+{
+        struct xen_machphys_mapping mapping;
+        unsigned long machine_to_phys_nr_ents;
+
+        if (HYPERVISOR_memory_op(XENMEM_machphys_mapping, &mapping) == 0) {
+                machine_to_phys_mapping = (unsigned long *)mapping.v_start;
+                machine_to_phys_nr_ents = mapping.max_mfn + 1;
+        } else {
+                machine_to_phys_nr_ents = MACH2PHYS_NR_ENTRIES;
+        }
+        machine_to_phys_order = fls(machine_to_phys_nr_ents - 1);
+}
+
 #ifdef CONFIG_X86_64
 static void convert_pfn_mfn(void *v)
 {