x86/execmem: fix ROX cache usage in Xen PV guests

The recently introduced ROX cache for modules is assuming large page
support in 64-bit mode without testing the related feature bit.  This
results in breakage when running as a Xen PV guest, as in this mode large
pages are not supported.

Fix that by testing the X86_FEATURE_PSE capability when deciding whether
to enable the ROX cache.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 2e45474 ("execmem: add support for cache of large ROX pages")
Signed-off-by: Juergen Gross <[email protected]>
Reported-by: Marek Marczykowski-Górecki <[email protected]>
Tested-by: Marek Marczykowski-Górecki <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Mike Rapoport (Microsoft) <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: jgross1

arch/x86/mm/init.c

@@ -1080,7 +1080,8 @@ struct execmem_info __init *execmem_arch_setup(void)
 
 	start = MODULES_VADDR + offset;
 
-	if (IS_ENABLED(CONFIG_ARCH_HAS_EXECMEM_ROX)) {
+	if (IS_ENABLED(CONFIG_ARCH_HAS_EXECMEM_ROX) &&
+	    cpu_feature_enabled(X86_FEATURE_PSE)) {
 		pgprot = PAGE_KERNEL_ROX;
 		flags = EXECMEM_KASAN_SHADOW | EXECMEM_ROX_CACHE;
 	} else {