From patchwork Wed Jan 7 10:32:06 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 426133 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 1994314007F; Wed, 7 Jan 2015 21:37:26 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Y8nzO-0001rx-7X; Wed, 07 Jan 2015 10:37:22 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Y8nu2-0006nz-2u for kernel-team@lists.ubuntu.com; Wed, 07 Jan 2015 10:31:50 +0000 Received: from av-217-129-142-138.netvisao.pt ([217.129.142.138] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1Y8nty-0004IZ-Vr; Wed, 07 Jan 2015 10:31:47 +0000 From: Luis Henriques To: Paul Mackerras Subject: [3.16.y-ckt stable] Patch "powerpc/powernv: Switch off MMU before entering nap/sleep/rvwinkle mode" has been added to staging queue Date: Wed, 7 Jan 2015 10:32:06 +0000 Message-Id: <1420626726-29545-1-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 X-Extended-Stable: 3.16 Cc: Benjamin Herrenschmidt , "Shreyas B. Prabhu" , kernel-team@lists.ubuntu.com, linuxppc-dev@lists.ozlabs.org X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 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-3.16.y-queue branch of the 3.16.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-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt4. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 8a4ec5805ab7292f0c05d9b052aa343af57e7015 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: Luis Henriques --- arch/powerpc/include/asm/reg.h | 2 ++ arch/powerpc/kernel/idle_power7.S | 18 +++++++++++++++++- 2 files changed, 19 insertions(+), 1 deletion(-) -- 2.1.4 diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index bffd89d27301..e73cdadab785 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 5cf3d367190d..a29f5b0f9d3e 100644 --- a/arch/powerpc/kernel/idle_power7.S +++ b/arch/powerpc/kernel/idle_power7.S @@ -101,7 +101,23 @@ _GLOBAL(power7_powersave_common) std r9,_MSR(r1) std r1,PACAR1(r13) -_GLOBAL(power7_enter_nap_mode) + /* + * 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