From e568006b9d828403397668864d9797dc4bfefd28 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Fri, 17 Jun 2016 11:32:00 +0530 Subject: [PATCH] powerpc/mm/hash: Don't add memory coherence if cache inhibited is set H_ENTER hcall handling in qemu had assumptions that a cache inhibited hpte entry won't have memory conference set. Also older kernel mentioned that some version of pHyp required this (the code removed by the below commit says: /* Make pHyp happy */ if ((rflags & _PAGE_NO_CACHE) && !(rflags & _PAGE_WRITETHRU)) hpte_r &= ~HPTE_R_M; But with older kernel we had some inconsistent memory conherence mapping. We always enabled memory conherence in the page fault path and removed memory conherence is _PAGE_NO_CACHE was set when we mapped the page via htab_bolt_mapping. The commit mentioned below tried to consolidate that by always enabling memory conherence. But as mentioned above that breaks Qemu H_ENTER handling. This patch update this such that we enable memory conherence only if cache inhibited is not set and bring fault handling, lpar and bolt mapping in sync. Fixes: commit 30bda41aba4e("powerpc/mm: Drop WIMG in favour of new constant") Reported-by: Darrick J. Wong Signed-off-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman --- arch/powerpc/mm/hash_utils_64.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c index b2740c67e172..5b22ba0b58bc 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -201,9 +201,8 @@ unsigned long htab_convert_pte_flags(unsigned long pteflags) /* * We can't allow hardware to update hpte bits. Hence always * set 'R' bit and set 'C' if it is a write fault - * Memory coherence is always enabled */ - rflags |= HPTE_R_R | HPTE_R_M; + rflags |= HPTE_R_R; if (pteflags & _PAGE_DIRTY) rflags |= HPTE_R_C; @@ -213,10 +212,15 @@ unsigned long htab_convert_pte_flags(unsigned long pteflags) if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_TOLERANT) rflags |= HPTE_R_I; - if ((pteflags & _PAGE_CACHE_CTL ) == _PAGE_NON_IDEMPOTENT) + else if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_NON_IDEMPOTENT) rflags |= (HPTE_R_I | HPTE_R_G); - if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_SAO) - rflags |= (HPTE_R_I | HPTE_R_W); + else if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_SAO) + rflags |= (HPTE_R_W | HPTE_R_I | HPTE_R_M); + else + /* + * Add memory coherence if cache inhibited is not set + */ + rflags |= HPTE_R_M; return rflags; } -- 2.20.1