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Mon, 16 Mar 2026 13:09:49 +0000 (GMT) From: Christian Borntraeger To: KVM Cc: Christian Borntraeger , Janosch Frank , David Hildenbrand , linux-s390 , Thomas Huth , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Alexander Gordeev Subject: [PATCH v3] KVM: s390: vsie: Avoid injecting machine check on signal Date: Mon, 16 Mar 2026 14:09:47 +0100 Message-ID: <20260316130947.40466-1-borntraeger@linux.ibm.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzE2MDA5NyBTYWx0ZWRfX7Q2QQY5BoSMw 9i2HSf3uO6yKtkZQmGX4yuoCjHjL444PiJsVKZ4HOseC1UtMTScYaO0t4WHFicaGh9iIXdrZvt1 ulmcKgWpBwHQ15vrsZvMZu9PyeFIOmnJLO4eYty37mB/c8ZMMXc5u3wWHVy1mfeWlH+Su/Pfcpd cr+tzeX0363Wwgj8ChxhCIkghDaT/iiFrk48L4tWWRtI5T4zTCa3mCu7NGPzYwkqotWSSaKOIrg k0DMuk6IL5k7w2lTa1kLOwuJRw6s+m0OSPnQ5mKvvC5F4f7fQTs1bQ3c+c8/0SrK4l9YQzzEXkA KPM9mKhPFzApmoc63akAx1nMNUXS3ljPWagOIwLeLtFJZ6bQ60mJaPhwODdAGd/OPmTKXv1nWNo mxPyym8uqU7l9/Ei2OgCDXLWu9IHStZkKtVrw47g8kfDINzi99I8QOkl0fij7sQWw1mkkx1rUsl J58bQHynqwlLWsHDgRw== X-Authority-Analysis: v=2.4 cv=GIQF0+NK c=1 sm=1 tr=0 ts=69b80121 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=q4CM764U_AQYIoPu550A:9 X-Proofpoint-ORIG-GUID: A_P1oOksFmSRs9E0OlPOGrzeV7La9sqy X-Proofpoint-GUID: A_P1oOksFmSRs9E0OlPOGrzeV7La9sqy X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-16_04,2026-03-16_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 priorityscore=1501 bulkscore=0 lowpriorityscore=0 malwarescore=0 phishscore=0 impostorscore=0 suspectscore=0 adultscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603160097 The recent XFER_TO_GUEST_WORK change resulted in a situation, where the vsie code would interpret a signal during work as a machine check during SIE as both use the EINTR return code. The exit_reason of the sie64a function has nothing to do with the kvm_run exit_reason. Rename it and define a specific code for machine checks instead of abusing -EINTR. rename exit_reason into sie_return to avoid the naming conflict and change the code flow in vsie.c to have a separate variable for rc and sie_return. Fixes: 2bd1337a1295e ("KVM: s390: Use generic VIRT_XFER_TO_GUEST_WORK functions") Signed-off-by: Christian Borntraeger --- v1->v2: instead of a band-aid, make the machine check more direct v2->v3: avoid overloading the rc variable in vsie.c arch/s390/include/asm/kvm_host.h | 3 +++ arch/s390/include/asm/stacktrace.h | 2 +- arch/s390/kernel/asm-offsets.c | 2 +- arch/s390/kernel/entry.S | 4 ++-- arch/s390/kernel/nmi.c | 4 ++-- arch/s390/kvm/kvm-s390.c | 15 ++++++++------- arch/s390/kvm/vsie.c | 7 +++++-- 7 files changed, 22 insertions(+), 15 deletions(-) diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index 64a50f0862aa..3039c88daa63 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -710,6 +710,9 @@ void kvm_arch_crypto_clear_masks(struct kvm *kvm); void kvm_arch_crypto_set_masks(struct kvm *kvm, unsigned long *apm, unsigned long *aqm, unsigned long *adm); +#define SIE64_RETURN_NORMAL 0 +#define SIE64_RETURN_MCCK 1 + int __sie64a(phys_addr_t sie_block_phys, struct kvm_s390_sie_block *sie_block, u64 *rsa, unsigned long gasce); diff --git a/arch/s390/include/asm/stacktrace.h b/arch/s390/include/asm/stacktrace.h index c9ae680a28af..ac3606c3babe 100644 --- a/arch/s390/include/asm/stacktrace.h +++ b/arch/s390/include/asm/stacktrace.h @@ -62,7 +62,7 @@ struct stack_frame { struct { unsigned long sie_control_block; unsigned long sie_savearea; - unsigned long sie_reason; + unsigned long sie_return; unsigned long sie_flags; unsigned long sie_control_block_phys; unsigned long sie_guest_asce; diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c index e1a5b5b54e4f..fbd26f3e9f96 100644 --- a/arch/s390/kernel/asm-offsets.c +++ b/arch/s390/kernel/asm-offsets.c @@ -63,7 +63,7 @@ int main(void) OFFSET(__SF_EMPTY, stack_frame, empty[0]); OFFSET(__SF_SIE_CONTROL, stack_frame, sie_control_block); OFFSET(__SF_SIE_SAVEAREA, stack_frame, sie_savearea); - OFFSET(__SF_SIE_REASON, stack_frame, sie_reason); + OFFSET(__SF_SIE_RETURN, stack_frame, sie_return); OFFSET(__SF_SIE_FLAGS, stack_frame, sie_flags); OFFSET(__SF_SIE_CONTROL_PHYS, stack_frame, sie_control_block_phys); OFFSET(__SF_SIE_GUEST_ASCE, stack_frame, sie_guest_asce); diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 4873fe9d891b..5817cb47b2d0 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -200,7 +200,7 @@ SYM_FUNC_START(__sie64a) stg %r3,__SF_SIE_CONTROL(%r15) # ...and virtual addresses stg %r4,__SF_SIE_SAVEAREA(%r15) # save guest register save area stg %r5,__SF_SIE_GUEST_ASCE(%r15) # save guest asce - xc __SF_SIE_REASON(8,%r15),__SF_SIE_REASON(%r15) # reason code = 0 + xc __SF_SIE_RETURN(8,%r15),__SF_SIE_RETURN(%r15) # return code = 0 mvc __SF_SIE_FLAGS(8,%r15),__TI_flags(%r14) # copy thread flags lmg %r0,%r13,0(%r4) # load guest gprs 0-13 mvi __TI_sie(%r14),1 @@ -237,7 +237,7 @@ SYM_INNER_LABEL(sie_exit, SYM_L_GLOBAL) xgr %r4,%r4 xgr %r5,%r5 lmg %r6,%r14,__SF_GPRS(%r15) # restore kernel registers - lg %r2,__SF_SIE_REASON(%r15) # return exit reason code + lg %r2,__SF_SIE_RETURN(%r15) # return sie return code BR_EX %r14 SYM_FUNC_END(__sie64a) EXPORT_SYMBOL(__sie64a) diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c index a55abbf65333..fc1f775e4517 100644 --- a/arch/s390/kernel/nmi.c +++ b/arch/s390/kernel/nmi.c @@ -487,8 +487,8 @@ void notrace s390_do_machine_check(struct pt_regs *regs) mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK); if (test_cpu_flag(CIF_MCCK_GUEST) && (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) { - /* Set exit reason code for host's later handling */ - *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR; + /* Set sie return code for host's later handling */ + *((long *)(regs->gprs[15] + __SF_SIE_RETURN)) = SIE64_RETURN_MCCK; } clear_cpu_flag(CIF_MCCK_GUEST); diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 1668580008c6..b93722b57d1c 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -4617,7 +4617,7 @@ static int vcpu_post_run_handle_fault(struct kvm_vcpu *vcpu) return 0; } -static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason) +static int vcpu_post_run(struct kvm_vcpu *vcpu, int sie_return) { struct mcck_volatile_info *mcck_info; struct sie_page *sie_page; @@ -4633,13 +4633,14 @@ static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason) vcpu->run->s.regs.gprs[14] = vcpu->arch.sie_block->gg14; vcpu->run->s.regs.gprs[15] = vcpu->arch.sie_block->gg15; - if (exit_reason == -EINTR) { + if (sie_return == SIE64_RETURN_MCCK) { sie_page = container_of(vcpu->arch.sie_block, struct sie_page, sie_block); mcck_info = &sie_page->mcck_info; kvm_s390_reinject_machine_check(vcpu, mcck_info); return 0; } + WARN_ON(sie_return != SIE64_RETURN_NORMAL); if (vcpu->arch.sie_block->icptcode > 0) { rc = kvm_handle_sie_intercept(vcpu); @@ -4678,7 +4679,7 @@ int noinstr kvm_s390_enter_exit_sie(struct kvm_s390_sie_block *scb, #define PSW_INT_MASK (PSW_MASK_EXT | PSW_MASK_IO | PSW_MASK_MCHECK) static int __vcpu_run(struct kvm_vcpu *vcpu) { - int rc, exit_reason; + int rc, sie_return; struct sie_page *sie_page = (struct sie_page *)vcpu->arch.sie_block; /* @@ -4718,9 +4719,9 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) guest_timing_enter_irqoff(); __disable_cpu_timer_accounting(vcpu); - exit_reason = kvm_s390_enter_exit_sie(vcpu->arch.sie_block, - vcpu->run->s.regs.gprs, - vcpu->arch.gmap->asce.val); + sie_return = kvm_s390_enter_exit_sie(vcpu->arch.sie_block, + vcpu->run->s.regs.gprs, + vcpu->arch.gmap->asce.val); __enable_cpu_timer_accounting(vcpu); guest_timing_exit_irqoff(); @@ -4743,7 +4744,7 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) } kvm_vcpu_srcu_read_lock(vcpu); - rc = vcpu_post_run(vcpu, exit_reason); + rc = vcpu_post_run(vcpu, sie_return); if (rc || guestdbg_exit_pending(vcpu)) { kvm_vcpu_srcu_read_unlock(vcpu); break; diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c index c0d36afd4023..42c53134e0b8 100644 --- a/arch/s390/kvm/vsie.c +++ b/arch/s390/kvm/vsie.c @@ -1123,6 +1123,7 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page, struc struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s; struct kvm_s390_sie_block *scb_o = vsie_page->scb_o; int guest_bp_isolation; + int sie_return = SIE64_RETURN_NORMAL; int rc = 0; handle_last_fault(vcpu, vsie_page, sg); @@ -1163,7 +1164,7 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page, struc goto xfer_to_guest_mode_check; } guest_timing_enter_irqoff(); - rc = kvm_s390_enter_exit_sie(scb_s, vcpu->run->s.regs.gprs, sg->asce.val); + sie_return = kvm_s390_enter_exit_sie(scb_s, vcpu->run->s.regs.gprs, sg->asce.val); guest_timing_exit_irqoff(); local_irq_enable(); } @@ -1178,11 +1179,13 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page, struc kvm_vcpu_srcu_read_lock(vcpu); - if (rc == -EINTR) { + if (sie_return == SIE64_RETURN_MCCK) { kvm_s390_reinject_machine_check(vcpu, &vsie_page->mcck_info); return 0; } + WARN_ON(sie_return != SIE64_RETURN_NORMAL); + if (rc > 0) rc = 0; /* we could still have an icpt */ else if (current->thread.gmap_int_code) -- 2.53.0