x86: CPA return early when requested feature is not available
Mask out the not supported bits (e.g. NX). If the clr/set masks
are empty after the mask return without changing anything.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index a629cea5e..f60b93d 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -405,8 +405,18 @@
static int change_page_attr_set_clr(unsigned long addr, int numpages,
pgprot_t mask_set, pgprot_t mask_clr)
{
- int ret = __change_page_attr_set_clr(addr, numpages, mask_set,
- mask_clr);
+ int ret;
+
+ /*
+ * Check, if we are requested to change a not supported
+ * feature:
+ */
+ mask_set = canon_pgprot(mask_set);
+ mask_clr = canon_pgprot(mask_clr);
+ if (!pgprot_val(mask_set) && !pgprot_val(mask_clr))
+ return 0;
+
+ ret = __change_page_attr_set_clr(addr, numpages, mask_set, mask_clr);
/*
* On success we use clflush, when the CPU supports it to