From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935840AbeEYNdN (ORCPT ); Fri, 25 May 2018 09:33:13 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:36528 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933214AbeEYNdM (ORCPT ); Fri, 25 May 2018 09:33:12 -0400 Date: Fri, 25 May 2018 06:33:08 -0700 From: Guenter Roeck To: Michael Neuling , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] powerpc/64s: Clear PCR on boot Message-ID: <20180525133308.GA17443@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: guenter@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: guenter@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 18, 2018 at 11:37:42AM +1000, Michael Neuling wrote: > Clear the PCR (Processor Compatibility Register) on boot to ensure we > are not running in a compatibility mode. > > We've seen this cause problems when a crash (and kdump) occurs while > running compat mode guests. The kdump kernel then runs with the PCR > set and causes problems. The symptom in the kdump kernel (also seen in > petitboot after fast-reboot) is early userspace programs taking > sigills on newer instructions (seen in libc). > Hi folks, this patch causes qemu to bail out with Trying to write privileged spr 338 (0x152) at c000000000033454 when running it with "-M powernv -cpu POWER8" and powernv_defconfig. Can you confirm that this is a bug in qemu ? Thanks, Guenter > Signed-off-by: Michael Neuling > Cc: stable@vger.kernel.org > Signed-off-by: Michael Ellerman > --- > arch/powerpc/kernel/cpu_setup_power.S | 6 ++++++ > arch/powerpc/kernel/dt_cpu_ftrs.c | 1 + > 2 files changed, 7 insertions(+) > > diff --git a/arch/powerpc/kernel/cpu_setup_power.S b/arch/powerpc/kernel/cpu_setup_power.S > index 3f30c994e931..458b928dbd84 100644 > --- a/arch/powerpc/kernel/cpu_setup_power.S > +++ b/arch/powerpc/kernel/cpu_setup_power.S > @@ -28,6 +28,7 @@ _GLOBAL(__setup_cpu_power7) > beqlr > li r0,0 > mtspr SPRN_LPID,r0 > + mtspr SPRN_PCR,r0 > mfspr r3,SPRN_LPCR > li r4,(LPCR_LPES1 >> LPCR_LPES_SH) > bl __init_LPCR_ISA206 > @@ -41,6 +42,7 @@ _GLOBAL(__restore_cpu_power7) > beqlr > li r0,0 > mtspr SPRN_LPID,r0 > + mtspr SPRN_PCR,r0 > mfspr r3,SPRN_LPCR > li r4,(LPCR_LPES1 >> LPCR_LPES_SH) > bl __init_LPCR_ISA206 > @@ -57,6 +59,7 @@ _GLOBAL(__setup_cpu_power8) > beqlr > li r0,0 > mtspr SPRN_LPID,r0 > + mtspr SPRN_PCR,r0 > mfspr r3,SPRN_LPCR > ori r3, r3, LPCR_PECEDH > li r4,0 /* LPES = 0 */ > @@ -78,6 +81,7 @@ _GLOBAL(__restore_cpu_power8) > beqlr > li r0,0 > mtspr SPRN_LPID,r0 > + mtspr SPRN_PCR,r0 > mfspr r3,SPRN_LPCR > ori r3, r3, LPCR_PECEDH > li r4,0 /* LPES = 0 */ > @@ -99,6 +103,7 @@ _GLOBAL(__setup_cpu_power9) > mtspr SPRN_PSSCR,r0 > mtspr SPRN_LPID,r0 > mtspr SPRN_PID,r0 > + mtspr SPRN_PCR,r0 > mfspr r3,SPRN_LPCR > LOAD_REG_IMMEDIATE(r4, LPCR_PECEDH | LPCR_PECE_HVEE | LPCR_HVICE | LPCR_HEIC) > or r3, r3, r4 > @@ -123,6 +128,7 @@ _GLOBAL(__restore_cpu_power9) > mtspr SPRN_PSSCR,r0 > mtspr SPRN_LPID,r0 > mtspr SPRN_PID,r0 > + mtspr SPRN_PCR,r0 > mfspr r3,SPRN_LPCR > LOAD_REG_IMMEDIATE(r4, LPCR_PECEDH | LPCR_PECE_HVEE | LPCR_HVICE | LPCR_HEIC) > or r3, r3, r4 > diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c > index 8ab51f6ca03a..c904477abaf3 100644 > --- a/arch/powerpc/kernel/dt_cpu_ftrs.c > +++ b/arch/powerpc/kernel/dt_cpu_ftrs.c > @@ -101,6 +101,7 @@ static void __restore_cpu_cpufeatures(void) > if (hv_mode) { > mtspr(SPRN_LPID, 0); > mtspr(SPRN_HFSCR, system_registers.hfscr); > + mtspr(SPRN_PCR, 0); > } > mtspr(SPRN_FSCR, system_registers.fscr); > > -- > 2.7.4