From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rW8m65t9QzDqsT for ; Fri, 17 Jun 2016 16:02:14 +1000 (AEST) Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u5H5xVkd090527 for ; Fri, 17 Jun 2016 02:02:11 -0400 Received: from e32.co.us.ibm.com (e32.co.us.ibm.com [32.97.110.150]) by mx0b-001b2d01.pphosted.com with ESMTP id 23jswdekqf-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 17 Jun 2016 02:02:11 -0400 Received: from localhost by e32.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 17 Jun 2016 00:02:10 -0600 From: "Aneesh Kumar K.V" To: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au Cc: linuxppc-dev@lists.ozlabs.org, "Aneesh Kumar K.V" Subject: [PATCH] powerpc/mm/hash: Don't add memory coherence if cache inhibited is set Date: Fri, 17 Jun 2016 11:32:00 +0530 Message-Id: <1466143320-8203-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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") Signed-off-by: Aneesh Kumar K.V --- 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 fcf676f7f522..32bf92d2e7ff 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; } -- 2.7.4