On Thu, Aug 16, 2018 at 1:47 PM Sean Christopherson
<sean.j.christopher...@intel.com> wrote:
>
> Fixes: 6b28baca9b1f ("x86/speculation/l1tf: Protect PROT_NONE PTEs against
> speculation")
This seems wrong.
That commit doesn't invert a cleared page table entry, because that
commit still required _PAGE_PROTNONE being set for a pte to be
inverted.
I'm assuming the real culprit is commit f22cc87f6c1f
("x86/speculation/l1tf: Invert all not present mappings") which made
it look at _just_ the present bit.
And yeah, that was wrong.
So I really think a much better patch would be the appended one-liner.
Note - it's whitespace-damaged by cut-and-paste, but it should be
obvious enough to apply by hand.
Can you test this one instead?
Linus
---
arch/x86/include/asm/pgtable-invert.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/pgtable-invert.h
b/arch/x86/include/asm/pgtable-invert.h
index 44b1203ece12..821438e91b77 100644
--- a/arch/x86/include/asm/pgtable-invert.h
+++ b/arch/x86/include/asm/pgtable-invert.h
@@ -6,7 +6,7 @@
static inline bool __pte_needs_invert(u64 val)
{
- return !(val & _PAGE_PRESENT);
+ return val && !(val & _PAGE_PRESENT);
}
/* Get a mask to xor with the page table entry to get the correct pfn. */
