From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 03C91C432C0 for ; Tue, 26 Nov 2019 20:15:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2A3C2084B for ; Tue, 26 Nov 2019 20:15:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727653AbfKZUPk (ORCPT ); Tue, 26 Nov 2019 15:15:40 -0500 Received: from mx2.suse.de ([195.135.220.15]:46726 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727318AbfKZUOY (ORCPT ); Tue, 26 Nov 2019 15:14:24 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 57A4FAE46; Tue, 26 Nov 2019 20:14:23 +0000 (UTC) From: Michal Suchanek To: linuxppc-dev@lists.ozlabs.org Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Oleg Nesterov , Alexander Viro , Christian Brauner , Nicholas Piggin , Allison Randal , "Naveen N. Rao" , Michal Suchanek , Thomas Gleixner , Breno Leitao , Christophe Leroy , Claudio Carvalho , Russell Currey , Greg Kroah-Hartman , Mahesh Salgaonkar , Arnd Bergmann , Geert Uytterhoeven , Firoz Khan , Dmitry Vyukov , Masahiro Yamada , Hari Bathini , Andrew Donnellan , Nicolai Stange , Valentin Schneider , Diana Craciun , Daniel Axtens , Michael Neuling , Gustavo Romero , Mathieu Malaterre , "Steven Rostedt" , "Eric W. Biederman" , Heiko Carstens , David Howells , Brajeswar Ghosh , Jagadeesh Pagadala , David Hildenbrand , Andrew Morton , Madhavan Srinivasan , linux-kernel@vger.kernel.org Subject: [PATCH v2 16/35] powerpc/64s/exception: hdecrementer avoid touching the stack Date: Tue, 26 Nov 2019 21:13:30 +0100 Message-Id: X-Mailer: git-send-email 2.23.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nicholas Piggin The hdec interrupt handler is reported to sometimes fire in Linux if KVM leaves it pending after a guest exists. This is harmless, so there is a no-op handler for it. The interrupt handler currently uses the regular kernel stack. Change this to avoid touching the stack entirely. This should be the last place where the regular Linux stack can be accessed with asynchronous interrupts (including PMI) soft-masked. It might be possible to take advantage of this invariant, e.g., to context switch the kernel stack SLB entry without clearing MSR[EE]. Signed-off-by: Nicholas Piggin --- arch/powerpc/include/asm/time.h | 1 - arch/powerpc/kernel/exceptions-64s.S | 25 ++++++++++++++++++++----- arch/powerpc/kernel/time.c | 9 --------- 3 files changed, 20 insertions(+), 15 deletions(-) diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h index 08dbe3e6831c..e0107495c4de 100644 --- a/arch/powerpc/include/asm/time.h +++ b/arch/powerpc/include/asm/time.h @@ -24,7 +24,6 @@ extern struct clock_event_device decrementer_clockevent; extern void generic_calibrate_decr(void); -extern void hdec_interrupt(struct pt_regs *regs); /* Some sane defaults: 125 MHz timebase, 1GHz processor */ extern unsigned long ppc_proc_freq; diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 9fa71d51ecf4..7a234e6d7bf5 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1491,6 +1491,8 @@ EXC_COMMON_BEGIN(decrementer_common) INT_DEFINE_BEGIN(hdecrementer) IVEC=0x980 IHSRR=EXC_HV + ISTACK=0 + IRECONCILE=0 IKVM_REAL=1 IKVM_VIRT=1 INT_DEFINE_END(hdecrementer) @@ -1502,11 +1504,24 @@ EXC_VIRT_BEGIN(hdecrementer, 0x4980, 0x80) GEN_INT_ENTRY hdecrementer, virt=1 EXC_VIRT_END(hdecrementer, 0x4980, 0x80) EXC_COMMON_BEGIN(hdecrementer_common) - GEN_COMMON hdecrementer - bl save_nvgprs - addi r3,r1,STACK_FRAME_OVERHEAD - bl hdec_interrupt - b ret_from_except + __GEN_COMMON_ENTRY hdecrementer + /* + * Hypervisor decrementer interrupts not caught by the KVM test + * shouldn't occur but are sometimes left pending on exit from a KVM + * guest. We don't need to do anything to clear them, as they are + * edge-triggered. + * + * Be careful to avoid touching the kernel stack. + */ + ld r10,PACA_EXGEN+EX_CTR(r13) + mtctr r10 + mtcrf 0x80,r9 + ld r9,PACA_EXGEN+EX_R9(r13) + ld r10,PACA_EXGEN+EX_R10(r13) + ld r11,PACA_EXGEN+EX_R11(r13) + ld r12,PACA_EXGEN+EX_R12(r13) + ld r13,PACA_EXGEN+EX_R13(r13) + HRFI_TO_KERNEL GEN_KVM hdecrementer diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 694522308cd5..bebc8c440289 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -663,15 +663,6 @@ void timer_broadcast_interrupt(void) } #endif -/* - * Hypervisor decrementer interrupts shouldn't occur but are sometimes - * left pending on exit from a KVM guest. We don't need to do anything - * to clear them, as they are edge-triggered. - */ -void hdec_interrupt(struct pt_regs *regs) -{ -} - #ifdef CONFIG_SUSPEND static void generic_suspend_disable_irqs(void) { -- 2.23.0 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A358C432C3 for ; Tue, 26 Nov 2019 20:50:24 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AA4792080F for ; Tue, 26 Nov 2019 20:50:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AA4792080F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 47Mwyj4P0TzDqHV for ; Wed, 27 Nov 2019 07:50:21 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=suse.de (client-ip=195.135.220.15; helo=mx1.suse.de; envelope-from=msuchanek@suse.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=suse.de Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) (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 47Mw9H08Z3zDqYJ for ; Wed, 27 Nov 2019 07:14:27 +1100 (AEDT) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 57A4FAE46; Tue, 26 Nov 2019 20:14:23 +0000 (UTC) From: Michal Suchanek To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v2 16/35] powerpc/64s/exception: hdecrementer avoid touching the stack Date: Tue, 26 Nov 2019 21:13:30 +0100 Message-Id: X-Mailer: git-send-email 2.23.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Madhavan Srinivasan , David Hildenbrand , Heiko Carstens , Claudio Carvalho , David Howells , Masahiro Yamada , Paul Mackerras , Christian Brauner , Breno Leitao , Michael Neuling , Nicolai Stange , Diana Craciun , Firoz Khan , Allison Randal , Mahesh Salgaonkar , Geert Uytterhoeven , "Naveen N. Rao" , Michal Suchanek , Valentin Schneider , Jagadeesh Pagadala , Arnd Bergmann , Nicholas Piggin , Alexander Viro , Steven Rostedt , Thomas Gleixner , Dmitry Vyukov , Daniel Axtens , Gustavo Romero , Mathieu Malaterre , Greg Kroah-Hartman , Oleg Nesterov , linux-kernel@vger.kernel.org, "Eric W. Biederman" , Andrew Donnellan , Brajeswar Ghosh , Hari Bathini , Andrew Morton Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Nicholas Piggin The hdec interrupt handler is reported to sometimes fire in Linux if KVM leaves it pending after a guest exists. This is harmless, so there is a no-op handler for it. The interrupt handler currently uses the regular kernel stack. Change this to avoid touching the stack entirely. This should be the last place where the regular Linux stack can be accessed with asynchronous interrupts (including PMI) soft-masked. It might be possible to take advantage of this invariant, e.g., to context switch the kernel stack SLB entry without clearing MSR[EE]. Signed-off-by: Nicholas Piggin --- arch/powerpc/include/asm/time.h | 1 - arch/powerpc/kernel/exceptions-64s.S | 25 ++++++++++++++++++++----- arch/powerpc/kernel/time.c | 9 --------- 3 files changed, 20 insertions(+), 15 deletions(-) diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h index 08dbe3e6831c..e0107495c4de 100644 --- a/arch/powerpc/include/asm/time.h +++ b/arch/powerpc/include/asm/time.h @@ -24,7 +24,6 @@ extern struct clock_event_device decrementer_clockevent; extern void generic_calibrate_decr(void); -extern void hdec_interrupt(struct pt_regs *regs); /* Some sane defaults: 125 MHz timebase, 1GHz processor */ extern unsigned long ppc_proc_freq; diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 9fa71d51ecf4..7a234e6d7bf5 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1491,6 +1491,8 @@ EXC_COMMON_BEGIN(decrementer_common) INT_DEFINE_BEGIN(hdecrementer) IVEC=0x980 IHSRR=EXC_HV + ISTACK=0 + IRECONCILE=0 IKVM_REAL=1 IKVM_VIRT=1 INT_DEFINE_END(hdecrementer) @@ -1502,11 +1504,24 @@ EXC_VIRT_BEGIN(hdecrementer, 0x4980, 0x80) GEN_INT_ENTRY hdecrementer, virt=1 EXC_VIRT_END(hdecrementer, 0x4980, 0x80) EXC_COMMON_BEGIN(hdecrementer_common) - GEN_COMMON hdecrementer - bl save_nvgprs - addi r3,r1,STACK_FRAME_OVERHEAD - bl hdec_interrupt - b ret_from_except + __GEN_COMMON_ENTRY hdecrementer + /* + * Hypervisor decrementer interrupts not caught by the KVM test + * shouldn't occur but are sometimes left pending on exit from a KVM + * guest. We don't need to do anything to clear them, as they are + * edge-triggered. + * + * Be careful to avoid touching the kernel stack. + */ + ld r10,PACA_EXGEN+EX_CTR(r13) + mtctr r10 + mtcrf 0x80,r9 + ld r9,PACA_EXGEN+EX_R9(r13) + ld r10,PACA_EXGEN+EX_R10(r13) + ld r11,PACA_EXGEN+EX_R11(r13) + ld r12,PACA_EXGEN+EX_R12(r13) + ld r13,PACA_EXGEN+EX_R13(r13) + HRFI_TO_KERNEL GEN_KVM hdecrementer diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 694522308cd5..bebc8c440289 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -663,15 +663,6 @@ void timer_broadcast_interrupt(void) } #endif -/* - * Hypervisor decrementer interrupts shouldn't occur but are sometimes - * left pending on exit from a KVM guest. We don't need to do anything - * to clear them, as they are edge-triggered. - */ -void hdec_interrupt(struct pt_regs *regs) -{ -} - #ifdef CONFIG_SUSPEND static void generic_suspend_disable_irqs(void) { -- 2.23.0