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KVM: s390: allow user space to handle instr 0x0000 

We will use illegal instruction 0x0000 for handling 2 byte sw breakpoints
from user space. As it can be enabled dynamically via a capability,
let's move setting of ICTL_OPEREXC to the post creation step, so we avoid
any races when enabling that capability just while adding new cpus.

Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
David Hildenbrand 2016-06-21 14:19:51 +02:00 committed by Christian Borntraeger
parent af1bae5497
commit 6502a34cfd
5 changed files with 43 additions and 2 deletions
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13
Documentation/virtual/kvm/api.txt
View File

@ -3857,6 +3857,19 @@ as a broadcast even in x2APIC mode in order to support physical x2APIC
without interrupt remapping. This is undesirable in logical mode,
where 0xff represents CPUs 0-7 in cluster 0.
7.8 KVM_CAP_S390_USER_INSTR0
Architectures: s390
Parameters: none
With this capability enabled, all illegal instructions 0x0000 (2 bytes) will
be intercepted and forwarded to user space. User space can use this
mechanism e.g. to realize 2-byte software breakpoints. The kernel will
not inject an operating exception for these instructions, user space has
to take care of that.
This capability can be enabled dynamically even if VCPUs were already
created and are running.
8. Other capabilities.
----------------------

2
arch/s390/include/asm/kvm_host.h
View File

@ -43,6 +43,7 @@
/* s390-specific vcpu->requests bit members */
#define KVM_REQ_ENABLE_IBS 8
#define KVM_REQ_DISABLE_IBS 9
#define KVM_REQ_ICPT_OPEREXC 10
#define SIGP_CTRL_C 0x80
#define SIGP_CTRL_SCN_MASK 0x3f
@ -666,6 +667,7 @@ struct kvm_arch{
int user_cpu_state_ctrl;
int user_sigp;
int user_stsi;
int user_instr0;
struct s390_io_adapter *adapters[MAX_S390_IO_ADAPTERS];
wait_queue_head_t ipte_wq;
int ipte_lock_count;

3
arch/s390/kvm/intercept.c
View File

@ -359,6 +359,9 @@ static int handle_operexc(struct kvm_vcpu *vcpu)
test_kvm_facility(vcpu->kvm, 74))
return handle_sthyi(vcpu);
if (vcpu->arch.sie_block->ipa == 0 && vcpu->kvm->arch.user_instr0)
return -EOPNOTSUPP;
return kvm_s390_inject_program_int(vcpu, PGM_OPERATION);
}

26
arch/s390/kvm/kvm-s390.c
View File

@ -364,6 +364,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_S390_USER_STSI:
case KVM_CAP_S390_SKEYS:
case KVM_CAP_S390_IRQ_STATE:
case KVM_CAP_S390_USER_INSTR0:
r = 1;
break;
case KVM_CAP_S390_MEM_OP:
@ -456,6 +457,16 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
return r;
}
static void icpt_operexc_on_all_vcpus(struct kvm *kvm)
{
unsigned int i;
struct kvm_vcpu *vcpu;
kvm_for_each_vcpu(i, vcpu, kvm) {
kvm_s390_sync_request(KVM_REQ_ICPT_OPEREXC, vcpu);
}
}
static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
{
int r;
@ -507,6 +518,12 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
kvm->arch.user_stsi = 1;
r = 0;
break;
case KVM_CAP_S390_USER_INSTR0:
VM_EVENT(kvm, 3, "%s", "ENABLE: CAP_S390_USER_INSTR0");
kvm->arch.user_instr0 = 1;
icpt_operexc_on_all_vcpus(kvm);
r = 0;
break;
default:
r = -EINVAL;
break;
@ -1836,6 +1853,8 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
vcpu->arch.gmap = vcpu->kvm->arch.gmap;
sca_add_vcpu(vcpu);
}
if (test_kvm_facility(vcpu->kvm, 74) || vcpu->kvm->arch.user_instr0)
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;
}
@ -1923,8 +1942,6 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
}
vcpu->arch.sie_block->riccbd = (unsigned long) &vcpu->run->s.regs.riccb;
vcpu->arch.sie_block->ictl |= ICTL_ISKE | ICTL_SSKE | ICTL_RRBE;
if (test_kvm_facility(vcpu->kvm, 74))
vcpu->arch.sie_block->ictl |= ICTL_OPEREXC;
if (vcpu->kvm->arch.use_cmma) {
rc = kvm_s390_vcpu_setup_cmma(vcpu);
@ -2369,6 +2386,11 @@ static int kvm_s390_handle_requests(struct kvm_vcpu *vcpu)
goto retry;
}
if (kvm_check_request(KVM_REQ_ICPT_OPEREXC, vcpu)) {
vcpu->arch.sie_block->ictl |= ICTL_OPEREXC;
goto retry;
}
/* nothing to do, just clear the request */
clear_bit(KVM_REQ_UNHALT, &vcpu->requests);

1
include/uapi/linux/kvm.h
View File

@ -867,6 +867,7 @@ struct kvm_ppc_smmu_info {
#define KVM_CAP_VCPU_ATTRIBUTES 127
#define KVM_CAP_MAX_VCPU_ID 128
#define KVM_CAP_X2APIC_API 129
#define KVM_CAP_S390_USER_INSTR0 130
#ifdef KVM_CAP_IRQ_ROUTING