From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x226rveqSr40+M/zc4X+uDyAU7nLrKbVbVQ/6JXtwhaGsWrogSYI7n4wmojJ/eDqMRpIFEwZV ARC-Seal: i=1; a=rsa-sha256; t=1517986831; cv=none; d=google.com; s=arc-20160816; b=Q97copJBphzeZTOIdFiLYT0WjwGETfVPVzLgPhNdwHa/eUBBEqmsb0H4cuK2IqGYx0 v9DupNoWtmGoCxOozRt+7g/6ptPoQBb99zkET7lBXK/Xn4t/G3Cow3hYhwEY5D6Lk4eO 7P51saPRTobKt9rM0o9Ma/QutME0D+acHQTzlbbAVxBAILDfOMw6WyosbEezLBM+B78m IYQmmOps2xi5Lxd/TRTZm0oMngDilBqR+f5kKf9JBilLUZGhwM+Pdd0smi8nBoo1BIjl 0Mys0kUHM7Xl9iOcklnDmNlmOQQS13yZ7T6GFd1KgE11+A4IgDj9UqFmQunea10QCFF9 wzHA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=message-id:references:in-reply-to:date:subject:cc:to:from :arc-authentication-results; bh=Wh6PiL7lEN2S9WC5KEbfyojB/mzrrIe4mHX0XokLQnA=; b=Wi9T2iTOca6SlzbVD6ktAUVrr8ScLShqEGsC9+bhuF+ceVVXCoxmNYZWDBmtQNqrN+ PMK0/qP+5ot5JBN77Q5RMwgC0TZ9VVTGcVYfINZ/haQiGq+NGdJMapf0vVCdXo0i9dYa Bo0YKdUwOLkFjHCnp6C9/CU80OXP+gVV0s4od4pKWIaQ7sTmEqVIN0llBAGY/18FNYtl Lu6gI98ZNZ4wRUt3CtoT2CrlULrkHG4AnNs3yMPqt+GFbBEyFOpWdhof7915xfbfz/nj 63AznR3/KWxHB6wZcmT8g4oh834TMd3vx1HW7tsJYhXHxLlflwhwdpW+6c/KH9mInaY8 M/Mw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of schwidefsky@de.ibm.com designates 148.163.156.1 as permitted sender) smtp.mailfrom=schwidefsky@de.ibm.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=ibm.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of schwidefsky@de.ibm.com designates 148.163.156.1 as permitted sender) smtp.mailfrom=schwidefsky@de.ibm.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=ibm.com From: Martin Schwidefsky To: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Cc: Heiko Carstens , Christian Borntraeger , Cornelia Huck , David Hildenbrand , Greg Kroah-Hartman , Jon Masters , Marcus Meissner , Jiri Kosina , Dominik Brodowski , Alan Cox , Pavel Machek , David Woodhouse Subject: [PATCH 5/6] s390: run user space and KVM guests with modified branch prediction Date: Wed, 7 Feb 2018 08:00:10 +0100 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1517986811-27819-1-git-send-email-schwidefsky@de.ibm.com> References: <1517986811-27819-1-git-send-email-schwidefsky@de.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18020707-0020-0000-0000-000003F31BF5 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18020707-0021-0000-0000-000042859549 Message-Id: <1517986811-27819-6-git-send-email-schwidefsky@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-07_01:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1802070089 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1591724559955029227?= X-GMAIL-MSGID: =?utf-8?q?1591724559955029227?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Define TIF_ISOLATE_BP and TIF_ISOLATE_BP_GUEST and add the necessary plumbing in entry.S to be able to run user space and KVM guests with limited branch prediction. To switch a user space process to limited branch prediction the s390_isolate_bp() function has to be call, and to run a vCPU of a KVM guest associated with the current task with limited branch prediction call s390_isolate_bp_guest(). Signed-off-by: Martin Schwidefsky --- arch/s390/include/asm/processor.h | 3 +++ arch/s390/include/asm/thread_info.h | 4 +++ arch/s390/kernel/entry.S | 51 +++++++++++++++++++++++++++++++++---- arch/s390/kernel/processor.c | 18 +++++++++++++ 4 files changed, 71 insertions(+), 5 deletions(-) diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h index 5f37f9c..7f2953c 100644 --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -378,6 +378,9 @@ extern void memcpy_absolute(void *, void *, size_t); memcpy_absolute(&(dest), &__tmp, sizeof(__tmp)); \ } while (0) +extern int s390_isolate_bp(void); +extern int s390_isolate_bp_guest(void); + #endif /* __ASSEMBLY__ */ #endif /* __ASM_S390_PROCESSOR_H */ diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h index 25d6ec3..83ba575 100644 --- a/arch/s390/include/asm/thread_info.h +++ b/arch/s390/include/asm/thread_info.h @@ -58,6 +58,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); #define TIF_GUARDED_STORAGE 4 /* load guarded storage control block */ #define TIF_PATCH_PENDING 5 /* pending live patching update */ #define TIF_PGSTE 6 /* New mm's will use 4K page tables */ +#define TIF_ISOLATE_BP 8 /* Run process with isolated BP */ +#define TIF_ISOLATE_BP_GUEST 9 /* Run KVM guests with isolated BP */ #define TIF_31BIT 16 /* 32bit process */ #define TIF_MEMDIE 17 /* is terminating due to OOM killer */ @@ -78,6 +80,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); #define _TIF_UPROBE _BITUL(TIF_UPROBE) #define _TIF_GUARDED_STORAGE _BITUL(TIF_GUARDED_STORAGE) #define _TIF_PATCH_PENDING _BITUL(TIF_PATCH_PENDING) +#define _TIF_ISOLATE_BP _BITUL(TIF_ISOLATE_BP) +#define _TIF_ISOLATE_BP_GUEST _BITUL(TIF_ISOLATE_BP_GUEST) #define _TIF_31BIT _BITUL(TIF_31BIT) #define _TIF_SINGLE_STEP _BITUL(TIF_SINGLE_STEP) diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index e6d7550..53145b5 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -107,6 +107,7 @@ _PIF_WORK = (_PIF_PER_TRAP | _PIF_SYSCALL_RESTART) aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE) j 3f 1: UPDATE_VTIME %r14,%r15,\timer + BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP 2: lg %r15,__LC_ASYNC_STACK # load async stack 3: la %r11,STACK_FRAME_OVERHEAD(%r15) .endm @@ -187,6 +188,40 @@ _PIF_WORK = (_PIF_PER_TRAP | _PIF_SYSCALL_RESTART) .popsection .endm + .macro BPENTER tif_ptr,tif_mask + .pushsection .altinstr_replacement, "ax" +662: .word 0xc004, 0x0000, 0x0000 # 6 byte nop + .word 0xc004, 0x0000, 0x0000 # 6 byte nop + .popsection +664: TSTMSK \tif_ptr,\tif_mask + jz . + 8 + .long 0xb2e8d000 + .pushsection .altinstructions, "a" + .long 664b - . + .long 662b - . + .word 82 + .byte 12 + .byte 12 + .popsection + .endm + + .macro BPEXIT tif_ptr,tif_mask + TSTMSK \tif_ptr,\tif_mask + .pushsection .altinstr_replacement, "ax" +662: jnz . + 8 + .long 0xb2e8d000 + .popsection +664: jz . + 8 + .long 0xb2e8c000 + .pushsection .altinstructions, "a" + .long 664b - . + .long 662b - . + .word 82 + .byte 8 + .byte 8 + .popsection + .endm + .section .kprobes.text, "ax" .Ldummy: /* @@ -240,9 +275,11 @@ ENTRY(__switch_to) */ ENTRY(sie64a) stmg %r6,%r14,__SF_GPRS(%r15) # save kernel registers + lg %r12,__LC_CURRENT stg %r2,__SF_EMPTY(%r15) # save control block pointer stg %r3,__SF_EMPTY+8(%r15) # save guest register save area xc __SF_EMPTY+16(8,%r15),__SF_EMPTY+16(%r15) # reason code = 0 + mvc __SF_EMPTY+24(8,%r15),__TI_flags(%r12) # copy thread flags TSTMSK __LC_CPU_FLAGS,_CIF_FPU # load guest fp/vx registers ? jno .Lsie_load_guest_gprs brasl %r14,load_fpu_regs # load guest fp/vx regs @@ -259,11 +296,12 @@ ENTRY(sie64a) jnz .Lsie_skip TSTMSK __LC_CPU_FLAGS,_CIF_FPU jo .Lsie_skip # exit if fp/vx regs changed - BPON + BPEXIT __SF_EMPTY+24(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST) .Lsie_entry: sie 0(%r14) .Lsie_exit: BPOFF + BPENTER __SF_EMPTY+24(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST) .Lsie_skip: ni __SIE_PROG0C+3(%r14),0xfe # no longer in SIE lctlg %c1,%c1,__LC_USER_ASCE # load primary asce @@ -324,6 +362,7 @@ ENTRY(system_call) la %r11,STACK_FRAME_OVERHEAD(%r15) # pointer to pt_regs .Lsysc_vtime: UPDATE_VTIME %r8,%r9,__LC_SYNC_ENTER_TIMER + BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP stmg %r0,%r7,__PT_R0(%r11) # clear user controlled register to prevent speculative use xgr %r0,%r0 @@ -362,7 +401,7 @@ ENTRY(system_call) jnz .Lsysc_work # check for work TSTMSK __LC_CPU_FLAGS,_CIF_WORK jnz .Lsysc_work - BPON + BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP .Lsysc_restore: lg %r14,__LC_VDSO_PER_CPU lmg %r0,%r10,__PT_R0(%r11) @@ -597,6 +636,7 @@ ENTRY(pgm_check_handler) aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE) j 4f 2: UPDATE_VTIME %r14,%r15,__LC_SYNC_ENTER_TIMER + BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP lg %r15,__LC_KERNEL_STACK lgr %r14,%r12 aghi %r14,__TASK_thread # pointer to thread_struct @@ -729,7 +769,7 @@ ENTRY(io_int_handler) mvc __LC_RETURN_PSW(16),__PT_PSW(%r11) tm __PT_PSW+1(%r11),0x01 # returning to user ? jno .Lio_exit_kernel - BPON + BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP .Lio_exit_timer: stpt __LC_EXIT_TIMER mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER @@ -1165,7 +1205,7 @@ ENTRY(mcck_int_handler) mvc __LC_RETURN_MCCK_PSW(16),__PT_PSW(%r11) # move return PSW tm __LC_RETURN_MCCK_PSW+1,0x01 # returning to user ? jno 0f - BPON + BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP stpt __LC_EXIT_TIMER mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER 0: lmg %r11,%r15,__PT_R11(%r11) @@ -1292,7 +1332,8 @@ cleanup_critical: clg %r9,BASED(.Lsie_crit_mcck_length) jh 1f oi __LC_CPU_FLAGS+7, _CIF_MCCK_GUEST -1: lg %r9,__SF_EMPTY(%r15) # get control block pointer +1: BPENTER __SF_EMPTY+24(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST) + lg %r9,__SF_EMPTY(%r15) # get control block pointer ni __SIE_PROG0C+3(%r9),0xfe # no longer in SIE lctlg %c1,%c1,__LC_USER_ASCE # load primary asce larl %r9,sie_exit # skip forward to sie_exit diff --git a/arch/s390/kernel/processor.c b/arch/s390/kernel/processor.c index 5362fd8..6fe2e18 100644 --- a/arch/s390/kernel/processor.c +++ b/arch/s390/kernel/processor.c @@ -197,3 +197,21 @@ const struct seq_operations cpuinfo_op = { .stop = c_stop, .show = show_cpuinfo, }; + +int s390_isolate_bp(void) +{ + if (!test_facility(82)) + return -EOPNOTSUPP; + set_thread_flag(TIF_ISOLATE_BP); + return 0; +} +EXPORT_SYMBOL(s390_isolate_bp); + +int s390_isolate_bp_guest(void) +{ + if (!test_facility(82)) + return -EOPNOTSUPP; + set_thread_flag(TIF_ISOLATE_BP_GUEST); + return 0; +} +EXPORT_SYMBOL(s390_isolate_bp_guest); -- 2.7.4