Re: [PATCH v2] powerpc/mm: Check for _PAGE_PTE in *_devmap()
From: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Date: 2017-07-28 01:14:54
On Fri, 2017-07-28 at 01:35 +1000, Oliver O'Halloran wrote:
The ISA radix translation tree contains two different types of entry,
s/entry/entries
quoted
directories and leaves. The formats of the two entries aredifferent with the directory entries containing no spare bits for use by software.
Rather than saying the directory entries contain no spare bits, would it be better to say something like: the devmap property only relates to pte (leaf) entries and so we shouldn't perform the check on/should always return false for page directory entries?
quoted hunk ↗ jump to hunk
As a result we need to ensure that the *_devmap() family of functions check fail for everything except leaf (PTE) entries. Signed-off-by: Oliver O'Halloran <oohall@gmail.com> --- "i'll just tweak the mbox before i sent it, what's the worst that can happen" *completely breaks KVM* "..." --- arch/powerpc/include/asm/book3s/64/pgtable.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.hb/arch/powerpc/include/asm/book3s/64/pgtable.h index d1da415..6bc6248 100644--- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h@@ -610,7 +610,9 @@ static inline pte_t pte_mkdevmap(pte_t pte)static inline int pte_devmap(pte_t pte) { - return !!(pte_raw(pte) & cpu_to_be64(_PAGE_DEVMAP)); + uint64_t mask = cpu_to_be64(_PAGE_DEVMAP | _PAGE_PTE); + + return (pte_raw(pte) & mask) == mask; } static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
Reviewed-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>