From 2444b352c3acf54897b0e2803a7c4e66699f9f43 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 9 Oct 2014 14:10:13 +0200 Subject: [PATCH] KVM: s390: forward most SIGP orders to user space Most SIGP orders are handled partially in kernel and partially in user space. In order to: - Get a correct SIGP SET PREFIX handler that informs user space - Avoid race conditions between concurrently executed SIGP orders - Serialize SIGP orders per VCPU We need to handle all "slow" SIGP orders in user space. The remaining ones to be handled completely in kernel are: - SENSE - SENSE RUNNING - EXTERNAL CALL - EMERGENCY SIGNAL - CONDITIONAL EMERGENCY SIGNAL According to the PoP, they have to be fast. They can be executed without conflicting to the actions of other pending/concurrently executing orders (e.g. STOP vs. START). This patch introduces a new capability that will - when enabled - forward all but the mentioned SIGP orders to user space. The instruction counters in the kernel are still updated. Reviewed-by: Cornelia Huck Signed-off-by: David Hildenbrand Signed-off-by: Christian Borntraeger --- Documentation/virtual/kvm/api.txt | 20 +++++++++++++ arch/s390/include/asm/kvm_host.h | 1 + arch/s390/kvm/kvm-s390.c | 5 ++++ arch/s390/kvm/sigp.c | 49 +++++++++++++++++++++++++++++++ include/uapi/linux/kvm.h | 1 + 5 files changed, 76 insertions(+) diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 3ca6e0e9a769..df19837e94d4 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -3225,3 +3225,23 @@ userspace from doing that. If the hcall number specified is not one that has an in-kernel implementation, the KVM_ENABLE_CAP ioctl will fail with an EINVAL error. + +7.2 KVM_CAP_S390_USER_SIGP + +Architectures: s390 +Parameters: none + +This capability controls which SIGP orders will be handled completely in user +space. With this capability enabled, all fast orders will be handled completely +in the kernel: +- SENSE +- SENSE RUNNING +- EXTERNAL CALL +- EMERGENCY SIGNAL +- CONDITIONAL EMERGENCY SIGNAL + +All other orders will be handled completely in user space. + +Only privileged operation exceptions will be checked for in the kernel (or even +in the hardware prior to interception). If this capability is not enabled, the +old way of handling SIGP orders is used (partially in kernel and user space). diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index b6170520380b..a2dcd0e099f7 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -521,6 +521,7 @@ struct kvm_arch{ int use_irqchip; int use_cmma; int user_cpu_state_ctrl; + int user_sigp; struct s390_io_adapter *adapters[MAX_S390_IO_ADAPTERS]; wait_queue_head_t ipte_wq; int ipte_lock_count; diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index bfb2b990da9b..3677b8ca647f 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -166,6 +166,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_S390_IRQCHIP: case KVM_CAP_VM_ATTRIBUTES: case KVM_CAP_MP_STATE: + case KVM_CAP_S390_USER_SIGP: r = 1; break; case KVM_CAP_NR_VCPUS: @@ -254,6 +255,10 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap) kvm->arch.use_irqchip = 1; r = 0; break; + case KVM_CAP_S390_USER_SIGP: + kvm->arch.user_sigp = 1; + r = 0; + break; default: r = -EINVAL; break; diff --git a/arch/s390/kvm/sigp.c b/arch/s390/kvm/sigp.c index 1524be9120ad..23b1e86b2122 100644 --- a/arch/s390/kvm/sigp.c +++ b/arch/s390/kvm/sigp.c @@ -371,6 +371,53 @@ static int handle_sigp_dst(struct kvm_vcpu *vcpu, u8 order_code, return rc; } +static int handle_sigp_order_in_user_space(struct kvm_vcpu *vcpu, u8 order_code) +{ + if (!vcpu->kvm->arch.user_sigp) + return 0; + + switch (order_code) { + case SIGP_SENSE: + case SIGP_EXTERNAL_CALL: + case SIGP_EMERGENCY_SIGNAL: + case SIGP_COND_EMERGENCY_SIGNAL: + case SIGP_SENSE_RUNNING: + return 0; + /* update counters as we're directly dropping to user space */ + case SIGP_STOP: + vcpu->stat.instruction_sigp_stop++; + break; + case SIGP_STOP_AND_STORE_STATUS: + vcpu->stat.instruction_sigp_stop_store_status++; + break; + case SIGP_STORE_STATUS_AT_ADDRESS: + vcpu->stat.instruction_sigp_store_status++; + break; + case SIGP_SET_PREFIX: + vcpu->stat.instruction_sigp_prefix++; + break; + case SIGP_START: + vcpu->stat.instruction_sigp_start++; + break; + case SIGP_RESTART: + vcpu->stat.instruction_sigp_restart++; + break; + case SIGP_INITIAL_CPU_RESET: + vcpu->stat.instruction_sigp_init_cpu_reset++; + break; + case SIGP_CPU_RESET: + vcpu->stat.instruction_sigp_cpu_reset++; + break; + default: + vcpu->stat.instruction_sigp_unknown++; + } + + VCPU_EVENT(vcpu, 4, "sigp order %u: completely handled in user space", + order_code); + + return 1; +} + int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu) { int r1 = (vcpu->arch.sie_block->ipa & 0x00f0) >> 4; @@ -385,6 +432,8 @@ int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu) return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP); order_code = kvm_s390_get_base_disp_rs(vcpu); + if (handle_sigp_order_in_user_space(vcpu, order_code)) + return -EOPNOTSUPP; if (r1 % 2) parameter = vcpu->run->s.regs.gprs[r1]; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index adc24a3fd23e..37f71c3040c3 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -759,6 +759,7 @@ struct kvm_ppc_smmu_info { #define KVM_CAP_PPC_FIXUP_HCALL 103 #define KVM_CAP_PPC_ENABLE_HCALL 104 #define KVM_CAP_CHECK_EXTENSION_VM 105 +#define KVM_CAP_S390_USER_SIGP 106 #ifdef KVM_CAP_IRQ_ROUTING -- 2.20.1