From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp08.in.ibm.com (e28smtp08.in.ibm.com [122.248.162.8]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e28smtp08.in.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id C90E02C010C for ; Wed, 2 Oct 2013 05:04:25 +1000 (EST) Received: from /spool/local by e28smtp08.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 2 Oct 2013 00:34:21 +0530 Received: from d28relay02.in.ibm.com (d28relay02.in.ibm.com [9.184.220.59]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id D71F9E0055 for ; Wed, 2 Oct 2013 00:35:26 +0530 (IST) Received: from d28av02.in.ibm.com (d28av02.in.ibm.com [9.184.220.64]) by d28relay02.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r91J6iVM38273096 for ; Wed, 2 Oct 2013 00:36:44 +0530 Received: from d28av02.in.ibm.com (localhost [127.0.0.1]) by d28av02.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id r91J4FR7020277 for ; Wed, 2 Oct 2013 00:34:15 +0530 From: Madhavan Srinivasan To: benh@kernel.crashing.org Subject: [PATCH v3] powerpc/kernel/sysfs: Disable writing to PURR in guest mode Date: Wed, 2 Oct 2013 00:34:10 +0530 Message-Id: <1380654250-11526-1-git-send-email-maddy@linux.vnet.ibm.com> Cc: linuxppc-dev@lists.ozlabs.org, Madhavan Srinivasan List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , powerpc/kernel/sysfs.c exports PURR with write permission. This may be valid for kernel in phyp mode. But writing to the file in guest mode causes crash. # echo 0 > purr cpu 0x0: Vector: 700 (Program Check) at [c000000000d072b0] pc: c00000000001770c: .write_purr+0x1c/0x40 lr: c000000000017708: .write_purr+0x18/0x40 sp: c000000000d07530 msr: 8000000000049032 current = 0xc000000000c53de0 paca = 0xc00000000ec70000 softe: 0 irq_happened: 0x01 pid = 0, comm = swapper/0 enter ? for help [c000000000d075b0] c0000000000fba64 .generic_smp_call_function_single_interrupt+0x104/0x190 [c000000000d07650] c000000000037748 .smp_ipi_demux+0xa8/0xf0 [c000000000d076e0] c000000000035314 .doorbell_exception+0x74/0xb0 [c000000000d07760] c000000000002950 doorbell_super_common+0x150/0x180 --- Exception: a01 (Doorbell) at c000000000060904 .plpar_hcall_norets+0x84/0xd4 [link register ] c00000000006dbd4 .check_and_cede_processor+0x24/0x40 [c000000000d07a50] c000000001002558 (unreliable) [c000000000d07ac0] c00000000006dd0c .shared_cede_loop+0x2c/0x70 [c000000000d07b40] c0000000006ae954 .cpuidle_enter_state+0x64/0x150 [c000000000d07c00] c0000000006aeb30 .cpuidle_idle_call+0xf0/0x300 [c000000000d07cb0] c000000000062fa0 .pseries_lpar_idle+0x10/0x50 [c000000000d07d20] c000000000016d14 .arch_cpu_idle+0x64/0x150 [c000000000d07da0] c0000000000e0060 .cpu_startup_entry+0x1a0/0x2c0 [c000000000d07e80] c00000000000bca4 .rest_init+0x94/0xb0 [c000000000d07ef0] c000000000b54530 .start_kernel+0x478/0x494 [c000000000d07f90] c000000000009be0 .start_here_common+0x20/0x40 0:mon> v3 changes: 1) Changed the test for to firmware lpar feature support instead of hypervisor 2) Removed type cast 3) changed the commit to explain better. v2 changes: 1) Changed the test for to hypervisor mode instead of platform Signed-off-by: Madhavan Srinivasan --- arch/powerpc/kernel/sysfs.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c index 27a90b9..b4e6676 100644 --- a/arch/powerpc/kernel/sysfs.c +++ b/arch/powerpc/kernel/sysfs.c @@ -17,6 +17,7 @@ #include #include #include +#include #include "cacheinfo.h" @@ -179,15 +180,25 @@ SYSFS_PMCSETUP(spurr, SPRN_SPURR); SYSFS_PMCSETUP(dscr, SPRN_DSCR); SYSFS_PMCSETUP(pir, SPRN_PIR); +/* + Lets only enable read for phyp resources and + enable write when needed with a separate function. + Lets be conservative and default to pseries. +*/ static DEVICE_ATTR(mmcra, 0600, show_mmcra, store_mmcra); static DEVICE_ATTR(spurr, 0400, show_spurr, NULL); static DEVICE_ATTR(dscr, 0600, show_dscr, store_dscr); -static DEVICE_ATTR(purr, 0600, show_purr, store_purr); +static DEVICE_ATTR(purr, 0400, show_purr, store_purr); static DEVICE_ATTR(pir, 0400, show_pir, NULL); unsigned long dscr_default = 0; EXPORT_SYMBOL(dscr_default); +static void add_write_permission_dev_attr(struct device_attribute *attr) +{ + attr->attr.mode |= 0200; +} + static ssize_t show_dscr_default(struct device *dev, struct device_attribute *attr, char *buf) { @@ -394,8 +405,11 @@ static void register_cpu_online(unsigned int cpu) if (cpu_has_feature(CPU_FTR_MMCRA)) device_create_file(s, &dev_attr_mmcra); - if (cpu_has_feature(CPU_FTR_PURR)) + if (cpu_has_feature(CPU_FTR_PURR)) { + if (!firmware_has_feature(FW_FEATURE_LPAR)) + add_write_permission_dev_attr(&dev_attr_purr); device_create_file(s, &dev_attr_purr); + } if (cpu_has_feature(CPU_FTR_SPURR)) device_create_file(s, &dev_attr_spurr); -- 1.7.10.4