x86/mm: Split read_cr3() into read_cr3_pa() and __read_cr3()

The kernel has several code paths that read CR3.  Most of them assume that
CR3 contains the PGD's physical address, whereas some of them awkwardly
use PHYSICAL_PAGE_MASK to mask off low bits.

Add explicit mask macros for CR3 and convert all of the CR3 readers.
This will keep them from breaking when PCID is enabled.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: xen-devel <xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/883f8fb121f4616c1c1427ad87350bb2f5ffeca1.1497288170.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/power/cpu.c

@@ -129,7 +129,7 @@ static void __save_processor_state(struct saved_context *ctxt)
 	 */
 	ctxt->cr0 = read_cr0();
 	ctxt->cr2 = read_cr2();
-	ctxt->cr3 = read_cr3();
+	ctxt->cr3 = __read_cr3();
 	ctxt->cr4 = __read_cr4();
 #ifdef CONFIG_X86_64
 	ctxt->cr8 = read_cr8();

arch/x86/power/hibernate_64.c

@@ -150,7 +150,8 @@ static int relocate_restore_code(void)
 	memcpy((void *)relocated_restore_code, &core_restore_code, PAGE_SIZE);
 
 	/* Make the page containing the relocated code executable */
-	pgd = (pgd_t *)__va(read_cr3()) + pgd_index(relocated_restore_code);
+	pgd = (pgd_t *)__va(read_cr3_pa()) +
+		pgd_index(relocated_restore_code);
 	p4d = p4d_offset(pgd, relocated_restore_code);
 	if (p4d_large(*p4d)) {
 		set_p4d(p4d, __p4d(p4d_val(*p4d) & ~_PAGE_NX));