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Violators will be prosecuted for from ; Wed, 26 Jun 2019 14:58:03 +0100 Subject: Re: [PATCH v5 2/2] s390/kvm: diagnose 318 handling References: <1561475022-18348-1-git-send-email-walling@linux.ibm.com> <1561475022-18348-3-git-send-email-walling@linux.ibm.com> From: Collin Walling Date: Wed, 26 Jun 2019 09:57:58 -0400 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Message-Id: <9a828de6-91ba-e37b-e5e7-92cc853bff0b@linux.ibm.com> Sender: linux-s390-owner@vger.kernel.org List-ID: To: David Hildenbrand , cohuck@redhat.com, pbonzini@redhat.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org On 6/26/19 5:08 AM, David Hildenbrand wrote: > On 25.06.19 17:03, Collin Walling wrote: >> DIAGNOSE 0x318 (diag318) is a privileged s390x instruction that must >> be intercepted by SIE and handled via KVM. Let's introduce some >> functions to communicate between userspace and KVM via ioctls. These >> will be used to get/set the diag318 related information, as well as >> check the system if KVM supports handling this instruction. >> >> This information can help with diagnosing the environment the VM is >> running in (Linux, z/VM, etc) if the OS calls this instruction. >> >> The get/set functions are introduced primarily for VM migration and >> reset, though no harm could be done to the system if a userspace >> program decides to alter this data (this is highly discouraged). >> >> The Control Program Name Code (CPNC) is stored in the SIE block (if >> host hardware supports it) and a copy is retained in each VCPU. The >> Control Program Version Code (CPVC) is not designed to be stored in >> the SIE block, so we retain a copy in each VCPU next to the CPNC. >> >> At this time, the CPVC is not reported during a VM_EVENT as its >> format is yet to be properly defined. >>> Signed-off-by: Collin Walling > > Only some minor comments. > > >> --- >> Documentation/virtual/kvm/devices/vm.txt | 14 ++++++ >> arch/s390/include/asm/kvm_host.h | 5 +- >> arch/s390/include/uapi/asm/kvm.h | 4 ++ >> arch/s390/kvm/diag.c | 17 +++++++ >> arch/s390/kvm/kvm-s390.c | 81 ++++++++++++++++++++++++++++++++ >> arch/s390/kvm/kvm-s390.h | 1 + >> arch/s390/kvm/vsie.c | 2 + >> 7 files changed, 123 insertions(+), 1 deletion(-) >> >> diff --git a/Documentation/virtual/kvm/devices/vm.txt b/Documentation/virtual/kvm/devices/vm.txt >> index 4ffb82b..56f7d9c 100644 >> --- a/Documentation/virtual/kvm/devices/vm.txt >> +++ b/Documentation/virtual/kvm/devices/vm.txt >> @@ -268,3 +268,17 @@ Parameters: address of a buffer in user space to store the data (u64) to; >> if it is enabled >> Returns: -EFAULT if the given address is not accessible from kernel space >> 0 in case of success. >> + >> +6. GROUP: KVM_S390_VM_MISC >> +Architectures: s390 >> + >> +6.1. KVM_S390_VM_MISC_DIAG318 (r/w) >> + >> +Allows userspace to access the DIAGNOSE 0x318 information which consists of a >> +1-byte "Control Program Name Code" and a 7-byte "Control Program Version Code". >> +This information is initialized during IPL and must be preserved during >> +migration. >> + >> +Parameters: address of a buffer in user space to store the data (u64) to >> +Returns: -EFAULT if the given address is not accessible from kernel space >> + 0 in case of success. >> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h >> index 2b00a3e..b70e8a4 100644 >> --- a/arch/s390/include/asm/kvm_host.h >> +++ b/arch/s390/include/asm/kvm_host.h >> @@ -229,7 +229,8 @@ struct kvm_s390_sie_block { >> __u32 scaol; /* 0x0064 */ >> __u8 reserved68; /* 0x0068 */ >> __u8 epdx; /* 0x0069 */ >> - __u8 reserved6a[2]; /* 0x006a */ >> + __u8 cpnc; /* 0x006a */ >> + __u8 reserved6b; /* 0x006b */ >> __u32 todpr; /* 0x006c */ >> #define GISA_FORMAT1 0x00000001 >> __u32 gd; /* 0x0070 */ >> @@ -393,6 +394,7 @@ struct kvm_vcpu_stat { >> u64 diagnose_9c; >> u64 diagnose_258; >> u64 diagnose_308; >> + u64 diagnose_318; >> u64 diagnose_500; >> u64 diagnose_other; >> }; >> @@ -868,6 +870,7 @@ struct kvm_arch{ >> DECLARE_BITMAP(cpu_feat, KVM_S390_VM_CPU_FEAT_NR_BITS); >> DECLARE_BITMAP(idle_mask, KVM_MAX_VCPUS); >> struct kvm_s390_gisa_interrupt gisa_int; >> + union diag318_info diag318_info; >> }; >> >> #define KVM_HVA_ERR_BAD (-1UL) >> diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h >> index 47104e5..e0684da 100644 >> --- a/arch/s390/include/uapi/asm/kvm.h >> +++ b/arch/s390/include/uapi/asm/kvm.h >> @@ -74,6 +74,7 @@ struct kvm_s390_io_adapter_req { >> #define KVM_S390_VM_CRYPTO 2 >> #define KVM_S390_VM_CPU_MODEL 3 >> #define KVM_S390_VM_MIGRATION 4 >> +#define KVM_S390_VM_MISC 5 >> >> /* kvm attributes for mem_ctrl */ >> #define KVM_S390_VM_MEM_ENABLE_CMMA 0 >> @@ -171,6 +172,9 @@ struct kvm_s390_vm_cpu_subfunc { >> #define KVM_S390_VM_MIGRATION_START 1 >> #define KVM_S390_VM_MIGRATION_STATUS 2 >> >> +/* kvm attributes for KVM_S390_VM_MISC */ >> +#define KVM_S390_VM_MISC_DIAG318 0 >> + >> /* for KVM_GET_REGS and KVM_SET_REGS */ >> struct kvm_regs { >> /* general purpose regs for s390 */ >> diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c >> index 45634b3d..42a8db3 100644 >> --- a/arch/s390/kvm/diag.c >> +++ b/arch/s390/kvm/diag.c >> @@ -235,6 +235,21 @@ static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu) >> return ret < 0 ? ret : 0; >> } >> >> +static int __diag_set_diag318_info(struct kvm_vcpu *vcpu) >> +{ >> + unsigned int reg = (vcpu->arch.sie_block->ipa & 0xf0) >> 4; >> + u64 info = vcpu->run->s.regs.gprs[reg]; >> + >> + vcpu->stat.diagnose_318++; >> + kvm_s390_set_diag318_info(vcpu->kvm, info); >> + >> + VCPU_EVENT(vcpu, 3, "diag 0x318 cpnc: 0x%x cpvc: 0x%llx", >> + vcpu->kvm->arch.diag318_info.cpnc, >> + (u64)vcpu->kvm->arch.diag318_info.cpvc); > > We have the event in kvm_s390_set_diag318_info(), do we really need this > one, too? > The other is a VM_EVENT, which I find more helpful than the VCPU_EVENT imho. I put this in here for consistency's sake with the rest of the __diag_* functions, but it certainly isn't needed. I'd vote to remove the VCPU event. >> + >> + return 0; >> +} >> + >> int kvm_s390_handle_diag(struct kvm_vcpu *vcpu) >> { >> int code = kvm_s390_get_base_disp_rs(vcpu, NULL) & 0xffff; >> @@ -254,6 +269,8 @@ int kvm_s390_handle_diag(struct kvm_vcpu *vcpu) >> return __diag_page_ref_service(vcpu); >> case 0x308: >> return __diag_ipl_functions(vcpu); >> + case 0x318: >> + return __diag_set_diag318_info(vcpu); >> case 0x500: >> return __diag_virtio_hypercall(vcpu); >> default: >> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >> index 28ebd64..8be9867 100644 >> --- a/arch/s390/kvm/kvm-s390.c >> +++ b/arch/s390/kvm/kvm-s390.c >> @@ -157,6 +157,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { >> { "instruction_diag_9c", VCPU_STAT(diagnose_9c) }, >> { "instruction_diag_258", VCPU_STAT(diagnose_258) }, >> { "instruction_diag_308", VCPU_STAT(diagnose_308) }, >> + { "instruction_diag_318", VCPU_STAT(diagnose_318) }, >> { "instruction_diag_500", VCPU_STAT(diagnose_500) }, >> { "instruction_diag_other", VCPU_STAT(diagnose_other) }, >> { NULL } >> @@ -1228,6 +1229,68 @@ static int kvm_s390_get_tod(struct kvm *kvm, struct kvm_device_attr *attr) >> return ret; >> } >> >> +void kvm_s390_set_diag318_info(struct kvm *kvm, u64 info) >> +{ >> + struct kvm_vcpu *vcpu; >> + int i; >> + >> + kvm->arch.diag318_info.val = info; >> + >> + VM_EVENT(kvm, 3, "SET: CPNC: 0x%x CPVC: 0x%llx", >> + kvm->arch.diag318_info.cpnc, (u64)kvm->arch.diag318_info.cpvc); >> + >> + if (sclp.has_diag318) { >> + kvm_for_each_vcpu(i, vcpu, kvm) { >> + vcpu->arch.sie_block->cpnc = kvm->arch.diag318_info.cpnc; >> + } > > If two CPUs would be executing this in parallel, we could create an > inconsistent cpnc value in the HW. Not sure if we care. > > Also, there is a possible race with CPU hotplug, depending on the > compiler optimizations if I'm not wrong. > > Sure we don't want to protect this by a mutex just to avoid having to > worry about such stuff? > > I guess, for ordinary guest operations, these races shouldn't matter. > The CPNC is harmless, but if we have the opportunity to protect ourselves from unwanted behavior, why not take it? I'll put the mutexes back in for the set operation. >> + } >> +} >> + >> +static int kvm_s390_set_misc(struct kvm *kvm, struct kvm_device_attr *attr) >> +{ >> + int ret; >> + u64 diag318_info; > > nit: reorder both > Noted. >> + >> + switch (attr->attr) { >> + case KVM_S390_VM_MISC_DIAG318: >> + ret = -EFAULT; >> + if (get_user(diag318_info, (u64 __user *)attr->addr)) >> + break; >> + kvm_s390_set_diag318_info(kvm, diag318_info); >> + ret = 0; >> + break; >> + default: >> + ret = -ENXIO; >> + break; >> + } >> + return ret; >> +} >> + >> +static int kvm_s390_get_diag318_info(struct kvm *kvm, struct kvm_device_attr *attr) >> +{ >> + if (put_user(kvm->arch.diag318_info.val, (u64 __user *)attr->addr)) >> + return -EFAULT; >> + >> + VM_EVENT(kvm, 3, "QUERY: CPNC: 0x%x, CPVC: 0x%llx", >> + kvm->arch.diag318_info.cpnc, (u64)kvm->arch.diag318_info.cpvc); > > Sure we need that cast / can't avoid it? > Compiler says we don't need it :) >> + return 0; >> +} >> + >> +static int kvm_s390_get_misc(struct kvm *kvm, struct kvm_device_attr *attr) >> +{ >> + int ret; >> + >> + switch (attr->attr) { >> + case KVM_S390_VM_MISC_DIAG318: >> + ret = kvm_s390_get_diag318_info(kvm, attr); >> + break; >> + default: >> + ret = -ENXIO; >> + break; >> + } >> + return ret; >> +} >> + >> static int kvm_s390_set_processor(struct kvm *kvm, struct kvm_device_attr *attr) >> { >> struct kvm_s390_vm_cpu_processor *proc; >> @@ -1674,6 +1737,9 @@ static int kvm_s390_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr) >> case KVM_S390_VM_MIGRATION: >> ret = kvm_s390_vm_set_migration(kvm, attr); >> break; >> + case KVM_S390_VM_MISC: >> + ret = kvm_s390_set_misc(kvm, attr); >> + break; >> default: >> ret = -ENXIO; >> break; >> @@ -1699,6 +1765,9 @@ static int kvm_s390_vm_get_attr(struct kvm *kvm, struct kvm_device_attr *attr) >> case KVM_S390_VM_MIGRATION: >> ret = kvm_s390_vm_get_migration(kvm, attr); >> break; >> + case KVM_S390_VM_MISC: >> + ret = kvm_s390_get_misc(kvm, attr); >> + break; >> default: >> ret = -ENXIO; >> break; >> @@ -1772,6 +1841,16 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr) >> case KVM_S390_VM_MIGRATION: >> ret = 0; >> break; >> + case KVM_S390_VM_MISC: >> + switch (attr->attr) { >> + case KVM_S390_VM_MISC_DIAG318: >> + ret = 0; >> + break; >> + default: >> + ret = -ENXIO; >> + break; >> + } >> + break; >> default: >> ret = -ENXIO; >> break; >> @@ -2892,6 +2971,8 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu) >> vcpu->arch.sie_block->ictl |= ICTL_OPEREXC; >> /* make vcpu_load load the right gmap on the first trigger */ >> vcpu->arch.enabled_gmap = vcpu->arch.gmap; >> + if (sclp.has_diag318) >> + vcpu->arch.sie_block->cpnc = vcpu->kvm->arch.diag318_info.cpnc; >> } >> >> static bool kvm_has_pckmo_subfunc(struct kvm *kvm, unsigned long nr) >> diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h >> index 6d9448d..70a21b4 100644 >> --- a/arch/s390/kvm/kvm-s390.h >> +++ b/arch/s390/kvm/kvm-s390.h >> @@ -281,6 +281,7 @@ int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu); >> int kvm_s390_handle_sigp_pei(struct kvm_vcpu *vcpu); >> >> /* implemented in kvm-s390.c */ >> +void kvm_s390_set_diag318_info(struct kvm *kvm, u64 info); >> void kvm_s390_set_tod_clock(struct kvm *kvm, >> const struct kvm_s390_vm_tod_clock *gtod); >> long kvm_arch_fault_in_page(struct kvm_vcpu *vcpu, gpa_t gpa, int writable); >> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c >> index 076090f..50e522e0 100644 >> --- a/arch/s390/kvm/vsie.c >> +++ b/arch/s390/kvm/vsie.c >> @@ -548,6 +548,8 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) >> scb_s->ecd |= scb_o->ecd & ECD_ETOKENF; >> >> scb_s->hpid = HPID_VSIE; >> + if (sclp.has_diag318) >> + scb_s->cpnc = scb_o->cpnc; >> >> prepare_ibc(vcpu, vsie_page); >> rc = shadow_crycb(vcpu, vsie_page); >> > > Thanks for the review!