From: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
Signed-off-by: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
Documentation/virtual/kvm/api.txt | 13 +++++++++++++
arch/s390/include/asm/kvm_host.h | 2 ++
arch/s390/kvm/intercept.c | 3 +++
arch/s390/kvm/kvm-s390.c | 26 ++++++++++++++++++++++++--
include/uapi/linux/kvm.h | 1 +
5 files changed, 43 insertions(+), 2 deletions(-)
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index c4d2fb0..299306d 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -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.
----------------------
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 946fc86..183b017 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -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;
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index 850be47..7a2f155 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -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);
}
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index d42428c..63ac7c1 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -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 @@ out:
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 @@ retry:
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);
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 4f8030e..70941f4 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -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
--
2.5.5
--
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