[GIT PULL 5/5] KVM: s390: implement KVM_(S|G)ET_MP_STATE for user space state control

Christian Borntraeger
2014-07-15T13:27:40Z

This patch
- adds s390 specific MP states to linux headers and documents them
- implements the KVM_{SET,GET}_MP_STATE ioctls
- enables KVM_CAP_MP_STATE
- allows user space to control the VCPU state on s390.

If user space sets the VCPU state using the ioctl KVM_SET_MP_STATE, we can disable
manual changing of the VCPU state and trust user space to do the right thing.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
Documentation/virtual/kvm/api.txt | 10 ++++++++--
arch/s390/include/asm/kvm_host.h | 1 +
arch/s390/kvm/diag.c | 3 ++-
arch/s390/kvm/intercept.c | 3 ++-
arch/s390/kvm/kvm-s390.c | 37 +++++++++++++++++++++++++++++++++----
arch/s390/kvm/kvm-s390.h | 6 ++++++
include/uapi/linux/kvm.h | 4 ++++
7 files changed, 56 insertions(+), 8 deletions(-)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 904c61c..a41465b 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -974,7 +974,7 @@ for vm-wide capabilities.
4.38 KVM_GET_MP_STATE

Capability: KVM_CAP_MP_STATE
-Architectures: x86, ia64
+Architectures: x86, ia64, s390
Type: vcpu ioctl
Parameters: struct kvm_mp_state (out)
Returns: 0 on success; -1 on error
@@ -998,6 +998,12 @@ Possible values are:
is waiting for an interrupt [x86, ia64]
- KVM_MP_STATE_SIPI_RECEIVED: the vcpu has just received a SIPI (vector
accessible via KVM_GET_VCPU_EVENTS) [x86, ia64]
+ - KVM_MP_STATE_STOPPED: the vcpu is stopped [s390]
+ - KVM_MP_STATE_CHECK_STOP: the vcpu is in a special error state [s390]
+ - KVM_MP_STATE_OPERATING: the vcpu is operating (running or halted)
+ [s390]
+ - KVM_MP_STATE_LOAD: the vcpu is in a special load/startup state
+ [s390]

On x86 and ia64, this ioctl is only useful after KVM_CREATE_IRQCHIP. Without an
in-kernel irqchip, the multiprocessing state must be maintained by userspace on
@@ -1007,7 +1013,7 @@ these architectures.
4.39 KVM_SET_MP_STATE

Capability: KVM_CAP_MP_STATE
-Architectures: x86, ia64
+Architectures: x86, ia64, s390
Type: vcpu ioctl
Parameters: struct kvm_mp_state (in)
Returns: 0 on success; -1 on error
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 4181d7b..c2ba020 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -418,6 +418,7 @@ struct kvm_arch{
int css_support;
int use_irqchip;
int use_cmma;
+ int user_cpu_state_ctrl;
struct s390_io_adapter *adapters[MAX_S390_IO_ADAPTERS];
wait_queue_head_t ipte_wq;
spinlock_t start_stop_lock;
diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
index 0161675..59bd8f9 100644
--- a/arch/s390/kvm/diag.c
+++ b/arch/s390/kvm/diag.c
@@ -176,7 +176,8 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
return -EOPNOTSUPP;
}

- kvm_s390_vcpu_stop(vcpu);
+ if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
+ kvm_s390_vcpu_stop(vcpu);
vcpu->run->s390_reset_flags |= KVM_S390_RESET_SUBSYSTEM;
vcpu->run->s390_reset_flags |= KVM_S390_RESET_IPL;
vcpu->run->s390_reset_flags |= KVM_S390_RESET_CPU_INIT;
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index ac6b325..eaf4629 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -73,7 +73,8 @@ static int handle_stop(struct kvm_vcpu *vcpu)
return rc;
}

- kvm_s390_vcpu_stop(vcpu);
+ if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
+ kvm_s390_vcpu_stop(vcpu);
return -EOPNOTSUPP;
}

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 3428953..fdf88f7 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -167,6 +167,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_DEVICE_CTRL:
case KVM_CAP_ENABLE_CAP_VM:
case KVM_CAP_VM_ATTRIBUTES:
+ case KVM_CAP_MP_STATE:
r = 1;
break;
case KVM_CAP_NR_VCPUS:
@@ -595,7 +596,8 @@ static void kvm_s390_vcpu_initial_reset(struct kvm_vcpu *vcpu)
vcpu->arch.sie_block->pp = 0;
vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
kvm_clear_async_pf_completion_queue(vcpu);
- kvm_s390_vcpu_stop(vcpu);
+ if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
+ kvm_s390_vcpu_stop(vcpu);
kvm_s390_clear_local_irqs(vcpu);
}

@@ -980,13 +982,34 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
struct kvm_mp_state *mp_state)
{
- return -EINVAL; /* not implemented yet */
+ /* CHECK_STOP and LOAD are not supported yet */
+ return is_vcpu_stopped(vcpu) ? KVM_MP_STATE_STOPPED :
+ KVM_MP_STATE_OPERATING;
}

int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
struct kvm_mp_state *mp_state)
{
- return -EINVAL; /* not implemented yet */
+ int rc = 0;
+
+ /* user space knows about this interface - let it control the state */
+ vcpu->kvm->arch.user_cpu_state_ctrl = 1;
+
+ switch (mp_state->mp_state) {
+ case KVM_MP_STATE_STOPPED:
+ kvm_s390_vcpu_stop(vcpu);
+ break;
+ case KVM_MP_STATE_OPERATING:
+ kvm_s390_vcpu_start(vcpu);
+ break;
+ case KVM_MP_STATE_LOAD:
+ case KVM_MP_STATE_CHECK_STOP:
+ /* fall through - CHECK_STOP and LOAD are not supported yet */
+ default:
+ rc = -ENXIO;
+ }
+
+ return rc;
}

bool kvm_s390_cmma_enabled(struct kvm *kvm)
@@ -1284,7 +1307,13 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
if (vcpu->sigset_active)
sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);

- kvm_s390_vcpu_start(vcpu);
+ if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm)) {
+ kvm_s390_vcpu_start(vcpu);
+ } else if (is_vcpu_stopped(vcpu)) {
+ pr_err_ratelimited("kvm-s390: can't run stopped vcpu %d\n",
+ vcpu->vcpu_id);
+ return -EINVAL;
+ }

switch (kvm_run->exit_reason) {
case KVM_EXIT_S390_SIEIC:
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 77ed846..33a0e4b 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -129,6 +129,12 @@ static inline void kvm_s390_set_psw_cc(struct kvm_vcpu *vcpu, unsigned long cc)
vcpu->arch.sie_block->gpsw.mask |= cc << 44;
}

+/* are cpu states controlled by user space */
+static inline int kvm_s390_user_cpu_state_ctrl(struct kvm *kvm)
+{
+ return kvm->arch.user_cpu_state_ctrl != 0;
+}
+
int kvm_s390_handle_wait(struct kvm_vcpu *vcpu);
enum hrtimer_restart kvm_s390_idle_wakeup(struct hrtimer *timer);
void kvm_s390_tasklet(unsigned long parm);
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 37d4ec6..9b744af 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -407,6 +407,10 @@ struct kvm_vapic_addr {
#define KVM_MP_STATE_INIT_RECEIVED 2
#define KVM_MP_STATE_HALTED 3
#define KVM_MP_STATE_SIPI_RECEIVED 4
+#define KVM_MP_STATE_STOPPED 5
+#define KVM_MP_STATE_CHECK_STOP 6
+#define KVM_MP_STATE_OPERATING 7
+#define KVM_MP_STATE_LOAD 8

struct kvm_mp_state {
__u32 mp_state;
--
1.8.4.2