x86/paravirt: add a pgd_alloc/free hooks

Add hooks which are called at pgd_alloc/free time.  The pgd_alloc hook
may return an error code, which if non-zero, causes the pgd allocation
to be failed.  The hooks may be used to allocate/free auxillary
per-pgd information.

also fix:

> * Ingo Molnar <mingo@elte.hu> wrote:
>
>  include/asm/pgalloc.h: In function ‘paravirt_pgd_free':
>  include/asm/pgalloc.h:14: error: parameter name omitted
>  arch/x86/kernel/entry_64.S: In file included from
>  arch/x86/kernel/traps_64.c:51:include/asm/pgalloc.h: In function ‘paravirt_pgd_free':
>  include/asm/pgalloc.h:14: error: parameter name omitted

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index e9b504537212..78c9a1b9e6b0 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -30,6 +30,7 @@
 #include <asm/setup.h>
 #include <asm/arch_hooks.h>
 #include <asm/time.h>
+#include <asm/pgalloc.h>
 #include <asm/irq.h>
 #include <asm/delay.h>
 #include <asm/fixmap.h>
@@ -366,6 +367,9 @@ struct pv_mmu_ops pv_mmu_ops = {
         .flush_tlb_single = native_flush_tlb_single,
         .flush_tlb_others = native_flush_tlb_others,
 
+        .pgd_alloc = __paravirt_pgd_alloc,
+        .pgd_free = paravirt_nop,
+
         .alloc_pte = paravirt_nop,
         .alloc_pmd = paravirt_nop,
         .alloc_pmd_clone = paravirt_nop,