On Wed, 24 Feb, at 08:39:56AM, Andy Lutomirski wrote:
>
> OK, although a comment might be nice.
Something like this?
---
>From ac40fc0269d4d8cc9051982c177ee140d6e1b761 Mon Sep 17 00:00:00 2001
From: Matt Fleming <m...@codeblueprint.co.uk>
Date: Thu, 25 Feb 2016 15:54:50 +0000
Subject: [PATCH] x86/mm/pat: Document the (currently) EFI-only code path
It's not at all obvious that populate_pgd() and friends are only
executed when mapping EFI virtual memory regions or that no other
pageattr callers pass a ->pgd value.
Reported-by: Andy Lutomirski <l...@amacapital.net>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Sai Praneeth Prakhya <sai.praneeth.prak...@intel.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Matt Fleming <m...@codeblueprint.co.uk>
---
arch/x86/mm/pageattr.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 14c38ae80409..8fee5b6f8f66 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -1125,8 +1125,14 @@ static int populate_pgd(struct cpa_data *cpa, unsigned
long addr)
static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr,
int primary)
{
- if (cpa->pgd)
+ if (cpa->pgd) {
+ /*
+ * Right now, we only execute this code path when mapping
+ * the EFI virtual memory map regions, no other users
+ * provide a ->pgd value. This may change in the future.
+ */
return populate_pgd(cpa, vaddr);
+ }
/*
* Ignore all non primary paths.
--
2.6.2
