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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id w81sm3831106wmg.19.2020.03.18.06.08.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2020 06:08:27 -0700 (PDT) From: Vitaly Kuznetsov To: Jon Doron , kvm@vger.kernel.org, linux-hyperv@vger.kernel.org Cc: Jon Doron Subject: Re: [PATCH v6 3/5] x86/kvm/hyper-v: Add support for synthetic debugger capability In-Reply-To: <20200317034804.112538-4-arilou@gmail.com> References: <20200317034804.112538-1-arilou@gmail.com> <20200317034804.112538-4-arilou@gmail.com> Date: Wed, 18 Mar 2020 14:08:26 +0100 Message-ID: <87o8st3j5h.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-hyperv-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org Jon Doron writes: > Add support for Hyper-V synthetic debugger (syndbg) interface. > The syndbg interface is using MSRs to emulate a way to send/recv packets > data. > > The debug transport dll (kdvm/kdnet) will identify if Hyper-V is enabled > and if it supports the synthetic debugger interface it will attempt to > use it, instead of trying to initialize a network adapter. > > Signed-off-by: Jon Doron > --- > Documentation/virt/kvm/api.rst | 16 ++++ > arch/x86/include/asm/kvm_host.h | 13 +++ > arch/x86/kvm/hyperv.c | 135 +++++++++++++++++++++++++++++++- > arch/x86/kvm/hyperv.h | 5 ++ > arch/x86/kvm/trace.h | 51 ++++++++++++ > arch/x86/kvm/x86.c | 9 +++ > include/uapi/linux/kvm.h | 11 +++ > 7 files changed, 239 insertions(+), 1 deletion(-) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index 4872c47bbcff..fe992dcf4f93 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -5024,6 +5024,7 @@ EOI was received. > struct kvm_hyperv_exit { > #define KVM_EXIT_HYPERV_SYNIC 1 > #define KVM_EXIT_HYPERV_HCALL 2 > + #define KVM_EXIT_HYPERV_SYNDBG 3 > __u32 type; > __u32 pad1; > union { > @@ -5039,6 +5040,15 @@ EOI was received. > __u64 result; > __u64 params[2]; > } hcall; > + struct { > + __u32 msr; > + __u32 pad2; > + __u64 control; > + __u64 status; > + __u64 send_page; > + __u64 recv_page; > + __u64 pending_page; > + } syndbg; > } u; > }; > /* KVM_EXIT_HYPERV */ > @@ -5055,6 +5065,12 @@ Hyper-V SynIC state change. Notification is used to remap SynIC > event/message pages and to enable/disable SynIC messages/events processing > in userspace. > > + - KVM_EXIT_HYPERV_SYNDBG -- synchronously notify user-space about > + > +Hyper-V Synthetic debugger state change. Notification is used to either update > +the pending_page location or to send a control command (send the buffer located > +in send_page or recv a buffer to recv_page). > + > :: > > /* KVM_EXIT_ARM_NISV */ > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 98959e8cd448..f8e58e8866bb 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -854,6 +854,18 @@ struct kvm_apic_map { > struct kvm_lapic *phys_map[]; > }; > > +/* Hyper-V synthetic debugger (SynDbg)*/ > +struct kvm_hv_syndbg { > + struct { > + u64 control; > + u64 status; > + u64 send_page; > + u64 recv_page; > + u64 pending_page; > + } control; > + u64 options; > +}; > + > /* Hyper-V emulation context */ > struct kvm_hv { > struct mutex hv_lock; > @@ -877,6 +889,7 @@ struct kvm_hv { > atomic_t num_mismatched_vp_indexes; > > struct hv_partition_assist_pg *hv_pa_pg; > + struct kvm_hv_syndbg hv_syndbg; > }; > > enum kvm_irqchip_mode { > diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c > index a86fda7a1d03..b6a97abe2bc9 100644 > --- a/arch/x86/kvm/hyperv.c > +++ b/arch/x86/kvm/hyperv.c > @@ -266,6 +266,107 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic, > return ret; > } > > +static int kvm_hv_syndbg_complete_userspace(struct kvm_vcpu *vcpu) > +{ > + struct kvm *kvm = vcpu->kvm; > + struct kvm_hv *hv = &kvm->arch.hyperv; > + > + if (vcpu->run->hyperv.u.syndbg.msr == HV_X64_MSR_SYNDBG_CONTROL) > + hv->hv_syndbg.control.status = > + vcpu->run->hyperv.u.syndbg.status; > + return 1; > +} > + > +static void syndbg_exit(struct kvm_vcpu *vcpu, u32 msr) > +{ > + struct kvm_hv_syndbg *syndbg = vcpu_to_hv_syndbg(vcpu); > + struct kvm_vcpu_hv *hv_vcpu = &vcpu->arch.hyperv; > + > + hv_vcpu->exit.type = KVM_EXIT_HYPERV_SYNDBG; > + hv_vcpu->exit.u.syndbg.msr = msr; > + hv_vcpu->exit.u.syndbg.control = syndbg->control.control; > + hv_vcpu->exit.u.syndbg.send_page = syndbg->control.send_page; > + hv_vcpu->exit.u.syndbg.recv_page = syndbg->control.recv_page; > + hv_vcpu->exit.u.syndbg.pending_page = syndbg->control.pending_page; > + vcpu->arch.complete_userspace_io = > + kvm_hv_syndbg_complete_userspace; > + > + kvm_make_request(KVM_REQ_HV_EXIT, vcpu); > +} > + > +static int syndbg_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data) > +{ > + struct kvm_hv_syndbg *syndbg = vcpu_to_hv_syndbg(vcpu); > + int ret; Minor nitpick: you could've initialized 'ret' to '0' here. But actually, looking at the code, you don't really need the return value as 'default' case can just BUG(): this can never happen. The whole function can be 'void'. > + > + trace_kvm_hv_syndbg_set_msr(vcpu->vcpu_id, > + vcpu_to_hv_vcpu(vcpu)->vp_index, msr, data); > + ret = 0; > + switch (msr) { > + case HV_X64_MSR_SYNDBG_CONTROL: > + syndbg->control.control = data; > + syndbg_exit(vcpu, msr); > + break; > + case HV_X64_MSR_SYNDBG_STATUS: > + syndbg->control.status = data; > + break; > + case HV_X64_MSR_SYNDBG_SEND_BUFFER: > + syndbg->control.send_page = data; > + break; > + case HV_X64_MSR_SYNDBG_RECV_BUFFER: > + syndbg->control.recv_page = data; > + break; > + case HV_X64_MSR_SYNDBG_PENDING_BUFFER: > + syndbg->control.pending_page = data; > + syndbg_exit(vcpu, msr); > + break; > + case HV_X64_MSR_SYNDBG_OPTIONS: > + syndbg->options = data; > + break; > + default: > + ret = 1; > + break; > + } > + > + return ret; > +} > + > +static int syndbg_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) > +{ > + struct kvm_hv_syndbg *syndbg = vcpu_to_hv_syndbg(vcpu); > + int ret; > + > + ret = 0; Same comment as the above. > + switch (msr) { > + case HV_X64_MSR_SYNDBG_CONTROL: > + *pdata = syndbg->control.control; > + break; > + case HV_X64_MSR_SYNDBG_STATUS: > + *pdata = syndbg->control.status; > + break; > + case HV_X64_MSR_SYNDBG_SEND_BUFFER: > + *pdata = syndbg->control.send_page; > + break; > + case HV_X64_MSR_SYNDBG_RECV_BUFFER: > + *pdata = syndbg->control.recv_page; > + break; > + case HV_X64_MSR_SYNDBG_PENDING_BUFFER: > + *pdata = syndbg->control.pending_page; > + break; > + case HV_X64_MSR_SYNDBG_OPTIONS: > + *pdata = syndbg->options; > + break; > + default: > + ret = 1; > + break; > + } > + > + trace_kvm_hv_syndbg_get_msr(vcpu->vcpu_id, > + vcpu_to_hv_vcpu(vcpu)->vp_index, msr, > + *pdata); > + return ret; > +} > + > static int synic_get_msr(struct kvm_vcpu_hv_synic *synic, u32 msr, u64 *pdata, > bool host) > { > @@ -800,6 +901,8 @@ static bool kvm_hv_msr_partition_wide(u32 msr) > case HV_X64_MSR_REENLIGHTENMENT_CONTROL: > case HV_X64_MSR_TSC_EMULATION_CONTROL: > case HV_X64_MSR_TSC_EMULATION_STATUS: > + case HV_X64_MSR_SYNDBG_OPTIONS: > + case HV_X64_MSR_SYNDBG_CONTROL ... HV_X64_MSR_SYNDBG_PENDING_BUFFER: > r = true; > break; > } > @@ -1061,6 +1164,9 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data, > if (!host) > return 1; > break; > + case HV_X64_MSR_SYNDBG_OPTIONS: > + case HV_X64_MSR_SYNDBG_CONTROL ... HV_X64_MSR_SYNDBG_PENDING_BUFFER: > + return syndbg_set_msr(vcpu, msr, data); > default: > vcpu_unimpl(vcpu, "Hyper-V unhandled wrmsr: 0x%x data 0x%llx\n", > msr, data); > @@ -1227,6 +1333,9 @@ static int kvm_hv_get_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) > case HV_X64_MSR_TSC_EMULATION_STATUS: > data = hv->hv_tsc_emulation_status; > break; > + case HV_X64_MSR_SYNDBG_OPTIONS: > + case HV_X64_MSR_SYNDBG_CONTROL ... HV_X64_MSR_SYNDBG_PENDING_BUFFER: > + return syndbg_get_msr(vcpu, msr, pdata); > default: > vcpu_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr); > return 1; > @@ -1797,6 +1906,9 @@ int kvm_vcpu_ioctl_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid, > { .function = HYPERV_CPUID_ENLIGHTMENT_INFO }, > { .function = HYPERV_CPUID_IMPLEMENT_LIMITS }, > { .function = HYPERV_CPUID_NESTED_FEATURES }, > + { .function = HYPERV_CPUID_SYNDBG_VENDOR_AND_MAX_FUNCTIONS }, > + { .function = HYPERV_CPUID_SYNDBG_INTERFACE }, > + { .function = HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES }, > }; > int i, nent = ARRAY_SIZE(cpuid_entries); > > @@ -1821,7 +1933,7 @@ int kvm_vcpu_ioctl_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid, > case HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS: > memcpy(signature, "Linux KVM Hv", 12); > > - ent->eax = HYPERV_CPUID_NESTED_FEATURES; > + ent->eax = HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES; This should depend on KVM_CAP_HYPERV_DEBUGGING being enabled (see below). > ent->ebx = signature[0]; > ent->ecx = signature[1]; > ent->edx = signature[2]; > @@ -1856,9 +1968,12 @@ int kvm_vcpu_ioctl_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid, > > ent->ebx |= HV_X64_POST_MESSAGES; > ent->ebx |= HV_X64_SIGNAL_EVENTS; > + ent->ebx |= HV_X64_DEBUGGING; > > ent->edx |= HV_FEATURE_FREQUENCY_MSRS_AVAILABLE; > ent->edx |= HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE; > + ent->edx |= HV_X64_GUEST_DEBUGGING_AVAILABLE; > + ent->edx |= HV_FEATURE_DEBUG_MSRS_AVAILABLE; > > /* > * Direct Synthetic timers only make sense with in-kernel > @@ -1903,6 +2018,24 @@ int kvm_vcpu_ioctl_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid, > > break; > > + case HYPERV_CPUID_SYNDBG_VENDOR_AND_MAX_FUNCTIONS: > + memcpy(signature, "Linux KVM Hv", 12); > + > + ent->eax = 0; > + ent->ebx = signature[0]; > + ent->ecx = signature[1]; > + ent->edx = signature[2]; > + break; > + > + case HYPERV_CPUID_SYNDBG_INTERFACE: > + memcpy(signature, "VS#1\0\0\0\0\0\0\0\0", 12); > + ent->eax = signature[0]; > + break; > + > + case HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES: > + ent->eax |= HV_X64_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING; > + break; > + > default: > break; > } > diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h > index 5e4780bf6dd7..29729258fa49 100644 > --- a/arch/x86/kvm/hyperv.h > +++ b/arch/x86/kvm/hyperv.h > @@ -73,6 +73,11 @@ static inline struct kvm_vcpu *synic_to_vcpu(struct kvm_vcpu_hv_synic *synic) > return hv_vcpu_to_vcpu(container_of(synic, struct kvm_vcpu_hv, synic)); > } > > +static inline struct kvm_hv_syndbg *vcpu_to_hv_syndbg(struct kvm_vcpu *vcpu) > +{ > + return &vcpu->kvm->arch.hyperv.hv_syndbg; > +} > + > int kvm_hv_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host); > int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host); > > diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h > index f194dd058470..bf6c3852868d 100644 > --- a/arch/x86/kvm/trace.h > +++ b/arch/x86/kvm/trace.h > @@ -1515,6 +1515,57 @@ TRACE_EVENT(kvm_nested_vmenter_failed, > __print_symbolic(__entry->err, VMX_VMENTER_INSTRUCTION_ERRORS)) > ); > > +/* > + * Tracepoint for syndbg_set_msr. > + */ > +TRACE_EVENT(kvm_hv_syndbg_set_msr, > + TP_PROTO(int vcpu_id, u32 vp_index, u32 msr, u64 data), > + TP_ARGS(vcpu_id, vp_index, msr, data), > + > + TP_STRUCT__entry( > + __field(int, vcpu_id) > + __field(u32, vp_index) > + __field(u32, msr) > + __field(u64, data) > + ), > + > + TP_fast_assign( > + __entry->vcpu_id = vcpu_id; > + __entry->vp_index = vp_index; > + __entry->msr = msr; > + __entry->data = data; > + ), > + > + TP_printk("vcpu_id %d vp_index %u msr 0x%x data 0x%llx", > + __entry->vcpu_id, __entry->vp_index, __entry->msr, > + __entry->data) > +); > + > +/* > + * Tracepoint for syndbg_get_msr. > + */ > +TRACE_EVENT(kvm_hv_syndbg_get_msr, > + TP_PROTO(int vcpu_id, u32 vp_index, u32 msr, u64 data), > + TP_ARGS(vcpu_id, vp_index, msr, data), > + > + TP_STRUCT__entry( > + __field(int, vcpu_id) > + __field(u32, vp_index) > + __field(u32, msr) > + __field(u64, data) > + ), > + > + TP_fast_assign( > + __entry->vcpu_id = vcpu_id; > + __entry->vp_index = vp_index; > + __entry->msr = msr; > + __entry->data = data; > + ), > + > + TP_printk("vcpu_id %d vp_index %u msr 0x%x data 0x%llx", > + __entry->vcpu_id, __entry->vp_index, __entry->msr, > + __entry->data) > +); > #endif /* _TRACE_KVM_H */ > > #undef TRACE_INCLUDE_PATH > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 5de200663f51..619c24bac79e 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1214,6 +1214,10 @@ static const u32 emulated_msrs_all[] = { > HV_X64_MSR_VP_ASSIST_PAGE, > HV_X64_MSR_REENLIGHTENMENT_CONTROL, HV_X64_MSR_TSC_EMULATION_CONTROL, > HV_X64_MSR_TSC_EMULATION_STATUS, > + HV_X64_MSR_SYNDBG_OPTIONS, > + HV_X64_MSR_SYNDBG_CONTROL, HV_X64_MSR_SYNDBG_STATUS, > + HV_X64_MSR_SYNDBG_SEND_BUFFER, HV_X64_MSR_SYNDBG_RECV_BUFFER, > + HV_X64_MSR_SYNDBG_PENDING_BUFFER, > > MSR_KVM_ASYNC_PF_EN, MSR_KVM_STEAL_TIME, > MSR_KVM_PV_EOI_EN, > @@ -2906,6 +2910,8 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > */ > break; > case HV_X64_MSR_GUEST_OS_ID ... HV_X64_MSR_SINT15: > + case HV_X64_MSR_SYNDBG_CONTROL ... HV_X64_MSR_SYNDBG_PENDING_BUFFER: > + case HV_X64_MSR_SYNDBG_OPTIONS: > case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4: > case HV_X64_MSR_CRASH_CTL: > case HV_X64_MSR_STIMER0_CONFIG ... HV_X64_MSR_STIMER3_COUNT: > @@ -3151,6 +3157,8 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > msr_info->data = 0x20000000; > break; > case HV_X64_MSR_GUEST_OS_ID ... HV_X64_MSR_SINT15: > + case HV_X64_MSR_SYNDBG_CONTROL ... HV_X64_MSR_SYNDBG_PENDING_BUFFER: > + case HV_X64_MSR_SYNDBG_OPTIONS: > case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4: > case HV_X64_MSR_CRASH_CTL: > case HV_X64_MSR_STIMER0_CONFIG ... HV_X64_MSR_STIMER3_COUNT: > @@ -3323,6 +3331,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > case KVM_CAP_HYPERV_TLBFLUSH: > case KVM_CAP_HYPERV_SEND_IPI: > case KVM_CAP_HYPERV_CPUID: > + case KVM_CAP_HYPERV_DEBUGGING: This is not enough: the userspace actually need to enable KVM_CAP_HYPERV_DEBUGGING to start receiving KVM_EXIT_HYPERV_SYNDBG. (see kvm_vcpu_ioctl_enable_cap()) Whem the capability is disabled, we should likely forbid writing to these debug MSRs. The problem here is: what if an unprepared userspace receives KVM_EXIT_HYPERV_SYNDBG? It will likely crash or misbehave (and this is guest triggerable!) so we need to prevent this. > case KVM_CAP_PCI_SEGMENT: > case KVM_CAP_DEBUGREGS: > case KVM_CAP_X86_ROBUST_SINGLESTEP: > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 7ee0ddc4c457..f20b81894f23 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -188,6 +188,7 @@ struct kvm_s390_cmma_log { > struct kvm_hyperv_exit { > #define KVM_EXIT_HYPERV_SYNIC 1 > #define KVM_EXIT_HYPERV_HCALL 2 > +#define KVM_EXIT_HYPERV_SYNDBG 3 > __u32 type; > __u32 pad1; > union { > @@ -203,6 +204,15 @@ struct kvm_hyperv_exit { > __u64 result; > __u64 params[2]; > } hcall; > + struct { > + __u32 msr; > + __u32 pad2; > + __u64 control; > + __u64 status; > + __u64 send_page; > + __u64 recv_page; > + __u64 pending_page; > + } syndbg; > } u; > }; > > @@ -1012,6 +1022,7 @@ struct kvm_ppc_resize_hpt { > #define KVM_CAP_ARM_NISV_TO_USER 177 > #define KVM_CAP_ARM_INJECT_EXT_DABT 178 > #define KVM_CAP_S390_VCPU_RESETS 179 > +#define KVM_CAP_HYPERV_DEBUGGING 180 I'd name this KVM_CAP_HYPERV_SYNDBG to not cause confusion. > > #ifdef KVM_CAP_IRQ_ROUTING -- Vitaly