From patchwork Wed Jan 28 22:20:14 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 434009 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [103.22.144.68]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 1FFB61402A4 for ; Thu, 29 Jan 2015 09:21:13 +1100 (AEDT) Received: from ozlabs.org (ozlabs.org [103.22.144.67]) by lists.ozlabs.org (Postfix) with ESMTP id 0E0AE1A0B5B for ; Thu, 29 Jan 2015 09:21:12 +1100 (AEDT) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from youngberry.canonical.com (youngberry.canonical.com [91.189.89.112]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id D22A11A09D4 for ; Thu, 29 Jan 2015 09:20:24 +1100 (AEDT) Received: from c-76-102-4-12.hsd1.ca.comcast.net ([76.102.4.12] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1YGay7-0003BQ-Ow; Wed, 28 Jan 2015 22:20:16 +0000 Received: from kamal by fourier with local (Exim 4.82) (envelope-from ) id 1YGay6-0003of-10; Wed, 28 Jan 2015 14:20:14 -0800 From: Kamal Mostafa To: Paul Mackerras Subject: [3.13.y-ckt stable] Patch "powerpc/powernv: Switch off MMU before entering nap/sleep/rvwinkle mode" has been added to staging queue Date: Wed, 28 Jan 2015 14:20:14 -0800 Message-Id: <1422483614-14638-1-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 X-Extended-Stable: 3.13 Cc: "Shreyas B. Prabhu" , Kamal Mostafa , kernel-team@lists.ubuntu.com, linuxppc-dev@lists.ozlabs.org X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" This is a note to let you know that I have just added a patch titled powerpc/powernv: Switch off MMU before entering nap/sleep/rvwinkle mode to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt15. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From eb5b1395c50d3eb178e31f229ef888172844e9a9 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Wed, 10 Dec 2014 00:26:50 +0530 Subject: powerpc/powernv: Switch off MMU before entering nap/sleep/rvwinkle mode commit 8117ac6a6c2fa0f847ff6a21a1f32c8d2c8501d0 upstream. Currently, when going idle, we set the flag indicating that we are in nap mode (paca->kvm_hstate.hwthread_state) and then execute the nap (or sleep or rvwinkle) instruction, all with the MMU on. This is bad for two reasons: (a) the architecture specifies that those instructions must be executed with the MMU off, and in fact with only the SF, HV, ME and possibly RI bits set, and (b) this introduces a race, because as soon as we set the flag, another thread can switch the MMU to a guest context. If the race is lost, this thread will typically start looping on relocation-on ISIs at 0xc...4400. This fixes it by setting the MSR as required by the architecture before setting the flag or executing the nap/sleep/rvwinkle instruction. [ shreyas@linux.vnet.ibm.com: Edited to handle LE ] Signed-off-by: Paul Mackerras Signed-off-by: Shreyas B. Prabhu Cc: Benjamin Herrenschmidt Cc: Michael Ellerman Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Michael Ellerman Signed-off-by: Kamal Mostafa --- arch/powerpc/include/asm/reg.h | 2 ++ arch/powerpc/kernel/idle_power7.S | 17 +++++++++++++++++ 2 files changed, 19 insertions(+) -- 1.9.1 diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index 637f513..663e5c2 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -118,8 +118,10 @@ #define __MSR (MSR_ME | MSR_RI | MSR_IR | MSR_DR | MSR_ISF |MSR_HV) #ifdef __BIG_ENDIAN__ #define MSR_ __MSR +#define MSR_IDLE (MSR_ME | MSR_SF | MSR_HV) #else #define MSR_ (__MSR | MSR_LE) +#define MSR_IDLE (MSR_ME | MSR_SF | MSR_HV | MSR_LE) #endif #define MSR_KERNEL (MSR_ | MSR_64BIT) #define MSR_USER32 (MSR_ | MSR_PR | MSR_EE) diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S index 847e40e..1fb7fee 100644 --- a/arch/powerpc/kernel/idle_power7.S +++ b/arch/powerpc/kernel/idle_power7.S @@ -84,6 +84,23 @@ _GLOBAL(power7_nap) std r9,_MSR(r1) std r1,PACAR1(r13) + /* + * Go to real mode to do the nap, as required by the architecture. + * Also, we need to be in real mode before setting hwthread_state, + * because as soon as we do that, another thread can switch + * the MMU context to the guest. + */ + LOAD_REG_IMMEDIATE(r5, MSR_IDLE) + li r6, MSR_RI + andc r6, r9, r6 + LOAD_REG_ADDR(r7, power7_enter_nap_mode) + mtmsrd r6, 1 /* clear RI before setting SRR0/1 */ + mtspr SPRN_SRR0, r7 + mtspr SPRN_SRR1, r5 + rfid + + .globl power7_enter_nap_mode +power7_enter_nap_mode: #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE /* Tell KVM we're napping */ li r4,KVM_HWTHREAD_IN_NAP