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Mon, 31 Aug 2026 14:48:12 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 31 Aug 2026 14:48:12 +0000 (GMT) From: Steffen Eiden To: kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Cc: Alexander Gordeev , Andreas Grapentin , Arnd Bergmann , Catalin Marinas , Christian Borntraeger , Claudio Imbrenda , David Hildenbrand , Friedrich Welter , Fuad Tabba , Gautam Gala , Hariharan Mari , Heiko Carstens , Hendrik Brueckner , Ilya Leoshkevich , Janosch Frank , Joey Gouly , Marc Zyngier , Nico Boehr , Nina Schoetterl-Glausch , Oliver Upton , Paolo Bonzini , Sean Christopherson , Suzuki K Poulose , Sven Schnelle , Ulrich Weigand , Vasily Gorbik , Will Deacon , Zenghui Yu Subject: [PATCH v7 22/23] KVM: s390: arm64: Implement basic page fault handler Date: Mon, 31 Aug 2026 16:47:59 +0200 Message-ID: <20260831144802.834315-23-seiden@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260831144802.834315-1-seiden@linux.ibm.com> References: <20260831144802.834315-1-seiden@linux.ibm.com> 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-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: k3mp160bxF5mgXhnXzzAI8he8oSHMBSp X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODMxMDEyNSBTYWx0ZWRfX03j3MJppJwi/ 9bplz1+lRky/WMexRWjhNj960TnAlyNhKb/Z2wa4SQGamqEhR2ZShQgMMbsbaHwMxbeEEmrXwHs dgJEdiinXsyPkvz852LruPqfvUcbNNB4Vi/eDI3JPf2fqScSPukbdMOP8RRbrEqOJplaiu4MXwX Acph3Bivy9as3LUqiXibTmPrY7tUoTRUAhwQCXhf2crVaGrkiVXf2rUiVbr9wauxCwg2m6GSs0x 5MTkdJ3Mm+OAyHXgRDGIikH1sPulnKEwwIrGP/GB0wd18Y4zF1Neve6Aq/dYDPEP7zmb+Nyfmo5 w/HHe8mqdnurQmxVoyITJpxUUgv/k5E1yFknN/3AzXFXWPwuXXVgJxiSQPfmYCiDDu8ctMz6GfO EUcKLR42Vl8vP2Ek+BkKl2xL7yon+MvKJZxVPU77euu3rrx8oWIJpEz1N4AnOif3osMavQNFtPJ fmBNkhBXJgsZ3QFB+IA== X-Authority-Analysis: v=2.4 cv=Osl/DS/t c=1 sm=1 tr=0 ts=6a959432 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=SwCwYoEPLhOQ47qcL8QA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwODMxMDEyNSBTYWx0ZWRfX0vOhS1Hf8j9o OLcFWKMPySU8IMqN0iSDukJc4FTPvPu80na1LNpvh01ooT2K2T6SEVsfA7O1YG76ecpA52hZ4HK XObclX3Wd9vD3Q53BORusiuMPQBoG68= X-Proofpoint-ORIG-GUID: sMJGdYUULO5uzMjDZzkXE8XdTypL0FcA X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-31_05,2026-08-27_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 malwarescore=0 suspectscore=0 bulkscore=0 lowpriorityscore=0 adultscore=0 impostorscore=0 phishscore=0 clxscore=1015 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608310125 Add host functionality to page in guest memory. If the guest does something unexpected or illegal exit to userspace abort guest execution. This behaviour will be changed to guest error injects once all sysregs are accessible for the host. Co-developed-by: Nina Schoetterl-Glausch Signed-off-by: Nina Schoetterl-Glausch Signed-off-by: Steffen Eiden --- arch/s390/kvm/arm64/handle_exit.c | 2 + arch/s390/kvm/arm64/mmio.c | 15 +++ arch/s390/kvm/arm64/mmu.c | 177 ++++++++++++++++++++++++++++++ arch/s390/kvm/arm64/trace.h | 24 ++++ 4 files changed, 218 insertions(+) create mode 100644 arch/s390/kvm/arm64/mmio.c create mode 100644 arch/s390/kvm/arm64/mmu.c diff --git a/arch/s390/kvm/arm64/handle_exit.c b/arch/s390/kvm/arm64/handle_exit.c index 1286a64783e0..8b03e8ee5acf 100644 --- a/arch/s390/kvm/arm64/handle_exit.c +++ b/arch/s390/kvm/arm64/handle_exit.c @@ -55,6 +55,8 @@ static int handle_hvc(struct kvm_vcpu *vcpu) static exit_handle_fn arm_exit_handlers[] = { [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec, [ESR_ELx_EC_HVC64] = handle_hvc, + [ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort, + [ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort, }; /* diff --git a/arch/s390/kvm/arm64/mmio.c b/arch/s390/kvm/arm64/mmio.c new file mode 100644 index 000000000000..908a6b43ddf7 --- /dev/null +++ b/arch/s390/kvm/arm64/mmio.c @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include + +#include + +#include +#include + +#include "trace.h" + +#define __INCL_GEN_ARM_FILE +#include "generated/mmio.inc" +#undef __INCL_GEN_ARM_FILE diff --git a/arch/s390/kvm/arm64/mmu.c b/arch/s390/kvm/arm64/mmu.c new file mode 100644 index 000000000000..bf3442d3609b --- /dev/null +++ b/arch/s390/kvm/arm64/mmu.c @@ -0,0 +1,177 @@ +// SPDX-License-Identifier: GPL-2.0 +#include + +#include + +#include + +static inline bool kvm_s390_cur_gmap_fault_is_write(struct kvm_vcpu *vcpu) +{ + return vcpu->arch.sae_block.hai.pic == PGM_PROTECTION || + vcpu->arch.sae_block.hai.teid.fsi == TEID_FSI_STORE; +} + +/* + * user_mem_abort() - handle a dat fault for the gmap of a vcpu + * + * Return: 0 on success, < 0 in case of error. + * Context: The mm lock must not be held before calling. May sleep. + */ +static int user_mem_abort(struct kvm_vcpu *vcpu, gpa_t fault_ipa, + struct kvm_memory_slot *slot, hva_t hva) +{ + struct guest_fault f = { }; + int ret; + + if (kvm_s390_cur_gmap_fault_is_write(vcpu)) + f.write_attempt = FOLL_WRITE; + f.gfn = gpa_to_gfn(fault_ipa); + + ret = kvm_s390_faultin_gfn(vcpu, NULL, &f); + if (ret <= 0) + return ret; + if (ret == PGM_ADDRESSING) + /* + * Without the relevant sysregs we cannot do anything for now. + * Go back to userspace with an error. TODO sysreg handling + */ + return -ENOEXEC; + KVM_BUG_ON(ret, vcpu->kvm); + return -EINVAL; +} + +static int kvm_handle_pic(struct kvm_vcpu *vcpu, bool *translation) +{ + switch (kvm_vcpu_fault_pic(vcpu)) { + /* expected cases: */ + case PGM_ASCE_TYPE: + case PGM_REGION_FIRST_TRANS: + case PGM_REGION_SECOND_TRANS: + case PGM_REGION_THIRD_TRANS: + case PGM_SEGMENT_TRANSLATION: + case PGM_PAGE_TRANSLATION: + *translation = true; + break; + case PGM_PROTECTION: + break; + /* unexpected cases: */ + case 0: + KVM_BUG(1, vcpu->kvm, "On MMU fault path but no fault occurred"); + return -EFAULT; + default: + KVM_BUG(1, vcpu->kvm, "Unexpected program interrupt 0x%x, TEID 0x%016lx", + vcpu->arch.sae_block.hai.pic, vcpu->arch.sae_block.hai.teid.val); + send_sig(SIGSEGV, current, 0); + return -EFAULT; + } + + return 0; +} + +int kvm_handle_guest_abort(struct kvm_vcpu *vcpu) +{ + struct kvm_memory_slot *memslot; + bool translation = false; + phys_addr_t fault_ipa; + unsigned long esr; + unsigned long hva; + bool write_fault; + bool guest_size_err; + bool writable; + bool is_iabt; + int ret; + gfn_t gfn; + int idx; + + esr = kvm_vcpu_get_esr(vcpu); + fault_ipa = kvm_vcpu_get_fault_ipa(vcpu); + is_iabt = kvm_vcpu_trap_is_iabt(vcpu); + guest_size_err = vcpu->arch.sae_block.icptr == SAE_ICPTR_GUEST_ADDRESS_SIZE; + + if (guest_size_err) { + translation = true; + } else { + ret = kvm_handle_pic(vcpu, &translation); + if (ret) + return ret; + } + + if (translation) { + /* + * For both cases: + * Without the relevant sysregs we cannot do anything for now. + * Go back to userspace with an error. TODO sysreg handling + */ + if (fault_ipa >= BIT_ULL(get_kvm_ipa_limit())) + return -ENOEXEC; + + if (fault_ipa >= vcpu->kvm->arch.guest_phys_size) + return -ENOEXEC; + } + + idx = srcu_read_lock(&vcpu->kvm->srcu); + + gfn = fault_ipa >> PAGE_SHIFT; + + memslot = gfn_to_memslot(vcpu->kvm, gfn); + hva = gfn_to_hva_memslot_prot(memslot, gfn, &writable); + write_fault = kvm_is_write_fault(vcpu); + if (kvm_is_error_hva(hva) || (write_fault && !writable)) { + ret = -ENOEXEC; + /* + * The guest has put either its instructions or its page-tables + * somewhere it shouldn't have. Userspace won't be able to do + * anything about this (there's no syndrome for a start). + * + * Without the relevant sysregs we cannot do anything for now. + * Go back to userspace with an error. TODO sysreg handling + */ + if (is_iabt) + goto out_unlock; + + if (kvm_vcpu_abt_iss1tw(vcpu)) { + /* + * Without the relevant sysregs we cannot do anything for now. + * Go back to userspace with an error. TODO sysreg handling + */ + goto out_unlock; + } + + /* + * Check for a cache maintenance operation. Assume the guest is + * cautious and skip instruction + */ + if (kvm_is_error_hva(hva) && kvm_vcpu_dabt_is_cm(vcpu)) { + kvm_incr_pc(vcpu); + ret = 1; + goto out_unlock; + } + + /* + * The IPA is reported as [MAX:12], so we need to + * complement it with the bottom 12 bits from the + * faulting VA. This is always 12 bits, irrespective + * of the page size. + */ + fault_ipa |= kvm_vcpu_get_hfar(vcpu) & ((1 << 12) - 1); + ret = io_mem_abort(vcpu, fault_ipa); + goto out_unlock; + } + + /* Userspace should not be able to register out-of-bounds IPAs */ + VM_BUG_ON(fault_ipa >= vcpu->kvm->arch.guest_phys_size); + /* + * Proper guest size faults have been injected. + * In theory it's fine to have device memory higher than MSL, + * even if not currently possible, but that would have been handled above. + * So if we get here with a guest size intercept, we have a bug somewhere. + */ + VM_BUG_ON(guest_size_err); + + ret = user_mem_abort(vcpu, fault_ipa, memslot, hva); + if (!ret) + ret = 1; +out_unlock: + srcu_read_unlock(&vcpu->kvm->srcu, idx); + return ret; +} diff --git a/arch/s390/kvm/arm64/trace.h b/arch/s390/kvm/arm64/trace.h index 1e3cb6108196..2a205ba0165c 100644 --- a/arch/s390/kvm/arm64/trace.h +++ b/arch/s390/kvm/arm64/trace.h @@ -7,6 +7,30 @@ #undef TRACE_SYSTEM #define TRACE_SYSTEM kvm_arm64 +TRACE_EVENT(kvm_mmio_nisv, + TP_PROTO(unsigned long vcpu_pc, unsigned long esr, + unsigned long far, unsigned long ipa), + TP_ARGS(vcpu_pc, esr, far, ipa), + + TP_STRUCT__entry( + __field( unsigned long, vcpu_pc ) + __field( unsigned long, esr ) + __field( unsigned long, far ) + __field( unsigned long, ipa ) + ), + + TP_fast_assign( + __entry->vcpu_pc = vcpu_pc; + __entry->esr = esr; + __entry->far = far; + __entry->ipa = ipa; + ), + + TP_printk("ipa %#016lx, esr %#016lx, far %#016lx, pc %#016lx", + __entry->ipa, __entry->esr, + __entry->far, __entry->vcpu_pc) +); + #endif /* KVM_ARM64_TRACE_KVM_H */ #undef TRACE_INCLUDE_PATH -- 2.53.0