From patchwork Fri Aug 1 09:18:06 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 4661681 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 5EE2D9F319 for ; Fri, 1 Aug 2014 09:21:20 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 8CF51201DD for ; Fri, 1 Aug 2014 09:21:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 928ED2010E for ; Fri, 1 Aug 2014 09:21:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755139AbaHAJVK (ORCPT ); Fri, 1 Aug 2014 05:21:10 -0400 Received: from cantor2.suse.de ([195.135.220.15]:49860 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754744AbaHAJSr (ORCPT ); Fri, 1 Aug 2014 05:18:47 -0400 Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 3205375046; Fri, 1 Aug 2014 09:18:36 +0000 (UTC) From: Alexander Graf To: kvm-ppc@vger.kernel.org Cc: kvm@vger.kernel.org, Mihai Caraman Subject: [PULL 35/63] KVM: PPC: e500mc: Revert "add load inst fixup" Date: Fri, 1 Aug 2014 11:18:06 +0200 Message-Id: <1406884714-33099-36-git-send-email-agraf@suse.de> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1406884714-33099-1-git-send-email-agraf@suse.de> References: <1406884714-33099-1-git-send-email-agraf@suse.de> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-7.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Mihai Caraman The commit 1d628af7 "add load inst fixup" made an attempt to handle failures generated by reading the guest current instruction. The fixup code that was added works by chance hiding the real issue. Load external pid (lwepx) instruction, used by KVM to read guest instructions, is executed in a subsituted guest translation context (EPLC[EGS] = 1). In consequence lwepx's TLB error and data storage interrupts need to be handled by KVM, even though these interrupts are generated from host context (MSR[GS] = 0) where lwepx is executed. Currently, KVM hooks only interrupts generated from guest context (MSR[GS] = 1), doing minimal checks on the fast path to avoid host performance degradation. As a result, the host kernel handles lwepx faults searching the faulting guest data address (loaded in DEAR) in its own Logical Partition ID (LPID) 0 context. In case a host translation is found the execution returns to the lwepx instruction instead of the fixup, the host ending up in an infinite loop. Revert the commit "add load inst fixup". lwepx issue will be addressed in a subsequent patch without needing fixup code. Signed-off-by: Mihai Caraman Signed-off-by: Alexander Graf --- arch/powerpc/kvm/bookehv_interrupts.S | 26 +------------------------- 1 file changed, 1 insertion(+), 25 deletions(-) diff --git a/arch/powerpc/kvm/bookehv_interrupts.S b/arch/powerpc/kvm/bookehv_interrupts.S index a1712b8..6ff4480 100644 --- a/arch/powerpc/kvm/bookehv_interrupts.S +++ b/arch/powerpc/kvm/bookehv_interrupts.S @@ -29,7 +29,6 @@ #include #include #include -#include #ifdef CONFIG_64BIT #include @@ -164,32 +163,9 @@ PPC_STL r30, VCPU_GPR(R30)(r4) PPC_STL r31, VCPU_GPR(R31)(r4) mtspr SPRN_EPLC, r8 - - /* disable preemption, so we are sure we hit the fixup handler */ - CURRENT_THREAD_INFO(r8, r1) - li r7, 1 - stw r7, TI_PREEMPT(r8) - isync - - /* - * In case the read goes wrong, we catch it and write an invalid value - * in LAST_INST instead. - */ -1: lwepx r9, 0, r5 -2: -.section .fixup, "ax" -3: li r9, KVM_INST_FETCH_FAILED - b 2b -.previous -.section __ex_table,"a" - PPC_LONG_ALIGN - PPC_LONG 1b,3b -.previous - + lwepx r9, 0, r5 mtspr SPRN_EPLC, r3 - li r7, 0 - stw r7, TI_PREEMPT(r8) stw r9, VCPU_LAST_INST(r4) .endif