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[92.18.20.3]) by smtp.gmail.com with ESMTPSA id c6sm20965438wma.15.2020.06.27.08.26.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 27 Jun 2020 08:26:22 -0700 (PDT) From: Beata Michalska To: qemu-devel@nongnu.org Subject: [PATCH v7 1/2] target/arm: kvm: Handle DABT with no valid ISS Date: Sat, 27 Jun 2020 16:25:55 +0100 Message-Id: <20200627152556.7391-2-beata.michalska@linaro.org> In-Reply-To: <20200627152556.7391-1-beata.michalska@linaro.org> References: <20200627152556.7391-1-beata.michalska@linaro.org> Received-SPF: pass client-ip=2a00:1450:4864:20::443; envelope-from=beata.michalska@linaro.org; helo=mail-wr1-x443.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org, drjones@redhat.com, Christoffer.Dall@arm.com, qemu-arm@nongnu.org, pbonzini@redhat.com, kvmarm@lists.cs.columbia.edu Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" On ARMv7 & ARMv8 some load/store instructions might trigger a data abort exception with no valid ISS info to be decoded. The lack of decode info makes it at least tricky to emulate those instruction which is one of the (many) reasons why KVM will not even try to do so. Add support for handling those by requesting KVM to inject external dabt into the quest. Signed-off-by: Beata Michalska --- target/arm/kvm.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 57 insertions(+), 1 deletion(-) diff --git a/target/arm/kvm.c b/target/arm/kvm.c index eef3bbd..3ea6f9a 100644 --- a/target/arm/kvm.c +++ b/target/arm/kvm.c @@ -39,6 +39,7 @@ const KVMCapabilityInfo kvm_arch_required_capabilities[] = { static bool cap_has_mp_state; static bool cap_has_inject_serror_esr; +static bool cap_has_inject_ext_dabt; static ARMHostCPUFeatures arm_host_cpu_features; @@ -245,6 +246,16 @@ int kvm_arch_init(MachineState *ms, KVMState *s) ret = -EINVAL; } + if (kvm_check_extension(s, KVM_CAP_ARM_NISV_TO_USER)) { + if (kvm_vm_enable_cap(s, KVM_CAP_ARM_NISV_TO_USER, 0)) { + error_report("Failed to enable KVM_CAP_ARM_NISV_TO_USER cap"); + } else { + /* Set status for supporting the external dabt injection */ + cap_has_inject_ext_dabt = kvm_check_extension(s, + KVM_CAP_ARM_INJECT_EXT_DABT); + } + } + return ret; } @@ -810,6 +821,46 @@ void kvm_arm_vm_state_change(void *opaque, int running, RunState state) } } +/** + * kvm_arm_handle_dabt_nisv: + * @cs: CPUState + * @esr_iss: ISS encoding (limited) for the exception from Data Abort + * ISV bit set to '0b0' -> no valid instruction syndrome + * @fault_ipa: faulting address for the synchronous data abort + * + * Returns: 0 if the exception has been handled, < 0 otherwise + */ +static int kvm_arm_handle_dabt_nisv(CPUState *cs, uint64_t esr_iss, + uint64_t fault_ipa) +{ + /* + * Request KVM to inject the external data abort into the guest + */ + if (cap_has_inject_ext_dabt) { + /* + * KVM_CAP_ARM_INJECT_EXT_DABT support implies one for + * KVM_CAP_VCPU_EVENTS + */ + struct kvm_vcpu_events events = { }; + /* + * The external data abort event will be handled immediately by KVM + * using the address fault that triggered the exit on given VCPU. + * Requesting injection of the external data abort does not rely + * on any other VCPU state. Therefore, in this particular case, the VCPU + * synchronization can be exceptionally skipped. + */ + events.exception.ext_dabt_pending = 1; + + return kvm_vcpu_ioctl(cs, KVM_SET_VCPU_EVENTS, &events); + } else { + error_report("Data abort exception triggered by guest memory access " + "at physical address: 0x" TARGET_FMT_lx, + (target_ulong)fault_ipa); + error_printf("KVM unable to emulate faulting instruction.\n"); + } + return -1; +} + int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run) { int ret = 0; @@ -820,7 +871,12 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run) ret = EXCP_DEBUG; } /* otherwise return to guest */ break; - default: + case KVM_EXIT_ARM_NISV: + /* External DABT with no valid iss to decode */ + ret = kvm_arm_handle_dabt_nisv(cs, run->arm_nisv.esr_iss, + run->arm_nisv.fault_ipa); + break; + default: qemu_log_mask(LOG_UNIMP, "%s: un-handled exit reason %d\n", __func__, run->exit_reason); break;