From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50800) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ct5ki-0006ZG-9j for qemu-devel@nongnu.org; Wed, 29 Mar 2017 01:02:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ct5kh-0005Os-BL for qemu-devel@nongnu.org; Wed, 29 Mar 2017 01:02:36 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:49979) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ct5kh-0005NN-1o for qemu-devel@nongnu.org; Wed, 29 Mar 2017 01:02:35 -0400 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v2T4wuOt078475 for ; Wed, 29 Mar 2017 01:02:30 -0400 Received: from e23smtp09.au.ibm.com (e23smtp09.au.ibm.com [202.81.31.142]) by mx0a-001b2d01.pphosted.com with ESMTP id 29ft0byv4u-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 29 Mar 2017 01:02:30 -0400 Received: from localhost by e23smtp09.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 29 Mar 2017 15:02:27 +1000 From: Sam Bobroff Date: Wed, 29 Mar 2017 16:01:27 +1100 Message-Id: Subject: [Qemu-devel] [PATCH 0/1] target/ppc: Improve accuracy of guest HTM availability on P8s List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-ppc@nongnu.org, david@gibson.dropbear.id.au, thuth@redhat.com Hi QEMU, See the patch itself for a description of the issue it's fixing. Additionally, I've done some investigation on the effect of the patch on older kernels. The discussion below only refers to the situation in which the existing workaround would have an effect (system is P8, KVM is HV and KVM does not indicate support for HTM): PPC_FEATURE2_HTM has existed since mid 2013 [1], and at that time it was unconditionally set for P8: nothing will change here because the new test will always be true, always allowing the workaround to activate. The patch doesn't help here. In early 2016 [2] PPC_FEATURE2_HTM was linked to the HTM bit of ibm,pa-features: the patch will help from here onwards. So the patch doesn't fix all situations but it doesn't break any either, and it fixes versions going forward. Cheers, Sam. 1: Around kernel commit cbbc6f1b1433ef553d57826eee87a84ca49645ce (v3.10-rc1) 2: Around kernel commit 4705e02498d6d5a7ab98dfee9595cd5e91db2017 (v4.6-rc1) Sam Bobroff (1): target/ppc: Improve accuracy of guest HTM availability on P8s target/ppc/kvm.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) -- 2.12.1.382.gc0f9c7058