[PATCH 0/8] Various Book3s HV fixes that haven't been picked up yet

[PATCH 0/8] Various Book3s HV fixes that haven't been picked up yet

[Paul Mackerras]

This is a set of 8 patches of which the first 7 have been posted
previously and have had no comments.  The 8th is new, but is quite
trivial.  They fix a series of issues with HV-style KVM on ppc.
They only touch code that is specific to Book3S HV KVM.
The patches are against the next branch of the kvm tree.

The overall diffstat is:

 arch/powerpc/include/asm/kvm_asm.h       |    1 +
 arch/powerpc/include/asm/kvm_book3s_64.h |    2 +-
 arch/powerpc/include/asm/kvm_host.h      |   17 +-
 arch/powerpc/include/asm/smp.h           |    8 +
 arch/powerpc/kernel/smp.c                |   46 +++++
 arch/powerpc/kvm/book3s_hv.c             |  316 +++++++++++++++++++++---------
 arch/powerpc/kvm/book3s_hv_rmhandlers.S  |   11 +-
 7 files changed, 293 insertions(+), 108 deletions(-)

Please apply.

Thanks,
Paul.

[PATCH 1/8] KVM: PPC: Book3S HV: Allow KVM guests to stop secondary threads coming online

[Paul Mackerras]

When a Book3S HV KVM guest is running, we need the host to be in
single-thread mode, that is, all of the cores (or at least all of
the cores where the KVM guest could run) to be running only one
active hardware thread.  This is because of the hardware restriction
in POWER processors that all of the hardware threads in the core
must be in the same logical partition.  Complying with this restriction
is much easier if, from the host kernel's point of view, only one
hardware thread is active.

This adds two hooks in the SMP hotplug code to allow the KVM code to
make sure that secondary threads (i.e. hardware threads other than
thread 0) cannot come online while any KVM guest exists.  The KVM
code still has to check that any core where it runs a guest has the
secondary threads offline, but having done that check it can now be
sure that they will not come online while the guest is running.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/include/asm/smp.h |    8 +++++++
 arch/powerpc/kernel/smp.c      |   46 ++++++++++++++++++++++++++++++++++++++++
 arch/powerpc/kvm/book3s_hv.c   |   12 +++++++++--
 3 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index ebc24dc..b625a1a 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -66,6 +66,14 @@ void generic_cpu_die(unsigned int cpu);
 void generic_mach_cpu_die(void);
 void generic_set_cpu_dead(unsigned int cpu);
 int generic_check_cpu_restart(unsigned int cpu);
+
+extern void inhibit_secondary_onlining(void);
+extern void uninhibit_secondary_onlining(void);
+
+#else /* HOTPLUG_CPU */
+static inline void inhibit_secondary_onlining(void) {}
+static inline void uninhibit_secondary_onlining(void) {}
+
 #endif
 
 #ifdef CONFIG_PPC64
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 8d4214a..c4f420c 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -417,6 +417,45 @@ int generic_check_cpu_restart(unsigned int cpu)
 {
 	return per_cpu(cpu_state, cpu) == CPU_UP_PREPARE;
 }
+
+static atomic_t secondary_inhibit_count;
+
+/*
+ * Don't allow secondary CPU threads to come online
+ */
+void inhibit_secondary_onlining(void)
+{
+	/*
+	 * This makes secondary_inhibit_count stable during cpu
+	 * online/offline operations.
+	 */
+	get_online_cpus();
+
+	atomic_inc(&secondary_inhibit_count);
+	put_online_cpus();
+}
+EXPORT_SYMBOL_GPL(inhibit_secondary_onlining);
+
+/*
+ * Allow secondary CPU threads to come online again
+ */
+void uninhibit_secondary_onlining(void)
+{
+	get_online_cpus();
+	atomic_dec(&secondary_inhibit_count);
+	put_online_cpus();
+}
+EXPORT_SYMBOL_GPL(uninhibit_secondary_onlining);
+
+static int secondaries_inhibited(void)
+{
+	return atomic_read(&secondary_inhibit_count);
+}
+
+#else /* HOTPLUG_CPU */
+
+#define secondaries_inhibited()		0
+
 #endif
 
 static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle)
@@ -435,6 +474,13 @@ int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
 {
 	int rc, c;
 
+	/*
+	 * Don't allow secondary threads to come online if inhibited
+	 */
+	if (threads_per_core > 1 && secondaries_inhibited() &&
+	    cpu % threads_per_core != 0)
+		return -EBUSY;
+
 	if (smp_ops == NULL ||
 	    (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
 		return -EINVAL;
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 9a15da7..c5ddf04 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -47,6 +47,7 @@
 #include <asm/page.h>
 #include <asm/hvcall.h>
 #include <asm/switch_to.h>
+#include <asm/smp.h>
 #include <linux/gfp.h>
 #include <linux/vmalloc.h>
 #include <linux/highmem.h>
@@ -1016,8 +1017,6 @@ static int kvmppc_run_core(struct kvmppc_vcore *vc)
 	/*
 	 * Make sure we are running on thread 0, and that
 	 * secondary threads are offline.
-	 * XXX we should also block attempts to bring any
-	 * secondary threads online.
 	 */
 	if (threads_per_core > 1 && !on_primary_thread()) {
 		list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list)
@@ -1730,11 +1729,20 @@ int kvmppc_core_init_vm(struct kvm *kvm)
 
 	kvm->arch.using_mmu_notifiers = !!cpu_has_feature(CPU_FTR_ARCH_206);
 	spin_lock_init(&kvm->arch.slot_phys_lock);
+
+	/*
+	 * Don't allow secondary CPU threads to come online
+	 * while any KVM VMs exist.
+	 */
+	inhibit_secondary_onlining();
+
 	return 0;
 }
 
 void kvmppc_core_destroy_vm(struct kvm *kvm)
 {
+	uninhibit_secondary_onlining();
+
 	if (kvm->arch.rma) {
 		kvm_release_rma(kvm->arch.rma);
 		kvm->arch.rma = NULL;
-- 
1.7.10.4

[PATCH 2/8] KVM: PPC: Book3S HV: Fix some races in starting secondary threads

[Paul Mackerras]

Subsequent patches implementing in-kernel XICS emulation will make it
possible for IPIs to arrive at secondary threads at arbitrary times.
This fixes some races in how we start the secondary threads, which
if not fixed could lead to occasional crashes of the host kernel.

This makes sure that (a) we have grabbed all the secondary threads,
and verified that they are no longer in the kernel, before we start
any thread, (b) that the secondary thread loads its vcpu pointer
after clearing the IPI that woke it up (so we don't miss a wakeup),
and (c) that the secondary thread clears its vcpu pointer before
incrementing the nap count.  It also removes unnecessary setting
of the vcpu and vcore pointers in the paca in kvmppc_core_vcpu_load.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/kvm/book3s_hv.c            |   41 ++++++++++++++++++-------------
 arch/powerpc/kvm/book3s_hv_rmhandlers.S |   11 ++++++---
 2 files changed, 32 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index c5ddf04..77dec0f 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -64,8 +64,6 @@ void kvmppc_core_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
 	struct kvmppc_vcore *vc = vcpu->arch.vcore;
 
-	local_paca->kvm_hstate.kvm_vcpu = vcpu;
-	local_paca->kvm_hstate.kvm_vcore = vc;
 	if (vc->runner == vcpu && vc->vcore_state != VCORE_INACTIVE)
 		vc->stolen_tb += mftb() - vc->preempt_tb;
 }
@@ -880,6 +878,7 @@ static int kvmppc_grab_hwthread(int cpu)
 
 	/* Ensure the thread won't go into the kernel if it wakes */
 	tpaca->kvm_hstate.hwthread_req = 1;
+	tpaca->kvm_hstate.kvm_vcpu = NULL;
 
 	/*
 	 * If the thread is already executing in the kernel (e.g. handling
@@ -929,7 +928,6 @@ static void kvmppc_start_thread(struct kvm_vcpu *vcpu)
 	smp_wmb();
 #if defined(CONFIG_PPC_ICP_NATIVE) && defined(CONFIG_SMP)
 	if (vcpu->arch.ptid) {
-		kvmppc_grab_hwthread(cpu);
 		xics_wake_cpu(cpu);
 		++vc->n_woken;
 	}
@@ -955,7 +953,8 @@ static void kvmppc_wait_for_nap(struct kvmppc_vcore *vc)
 
 /*
  * Check that we are on thread 0 and that any other threads in
- * this core are off-line.
+ * this core are off-line.  Then grab the threads so they can't
+ * enter the kernel.
  */
 static int on_primary_thread(void)
 {
@@ -967,6 +966,17 @@ static int on_primary_thread(void)
 	while (++thr < threads_per_core)
 		if (cpu_online(cpu + thr))
 			return 0;
+
+	/* Grab all hw threads so they can't go into the kernel */
+	for (thr = 1; thr < threads_per_core; ++thr) {
+		if (kvmppc_grab_hwthread(cpu + thr)) {
+			/* Couldn't grab one; let the others go */
+			do {
+				kvmppc_release_hwthread(cpu + thr);
+			} while (--thr > 0);
+			return 0;
+		}
+	}
 	return 1;
 }
 
@@ -1015,16 +1025,6 @@ static int kvmppc_run_core(struct kvmppc_vcore *vc)
 	}
 
 	/*
-	 * Make sure we are running on thread 0, and that
-	 * secondary threads are offline.
-	 */
-	if (threads_per_core > 1 && !on_primary_thread()) {
-		list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list)
-			vcpu->arch.ret = -EBUSY;
-		goto out;
-	}
-
-	/*
 	 * Assign physical thread IDs, first to non-ceded vcpus
 	 * and then to ceded ones.
 	 */
@@ -1043,15 +1043,22 @@ static int kvmppc_run_core(struct kvmppc_vcore *vc)
 		if (vcpu->arch.ceded)
 			vcpu->arch.ptid = ptid++;
 
+	/*
+	 * Make sure we are running on thread 0, and that
+	 * secondary threads are offline.
+	 */
+	if (threads_per_core > 1 && !on_primary_thread()) {
+		list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list)
+			vcpu->arch.ret = -EBUSY;
+		goto out;
+	}
+
 	vc->stolen_tb += mftb() - vc->preempt_tb;
 	vc->pcpu = smp_processor_id();
 	list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) {
 		kvmppc_start_thread(vcpu);
 		kvmppc_create_dtl_entry(vcpu, vc);
 	}
-	/* Grab any remaining hw threads so they can't go into the kernel */
-	for (i = ptid; i < threads_per_core; ++i)
-		kvmppc_grab_hwthread(vc->pcpu + i);
 
 	preempt_disable();
 	spin_unlock(&vc->lock);
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 44b72fe..1e90ef6 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -134,8 +134,11 @@ kvm_start_guest:
 
 27:	/* XXX should handle hypervisor maintenance interrupts etc. here */
 
+	/* reload vcpu pointer after clearing the IPI */
+	ld	r4,HSTATE_KVM_VCPU(r13)
+	cmpdi	r4,0
 	/* if we have no vcpu to run, go back to sleep */
-	beq	cr1,kvm_no_guest
+	beq	kvm_no_guest
 
 	/* were we napping due to cede? */
 	lbz	r0,HSTATE_NAPPING(r13)
@@ -1587,6 +1590,10 @@ secondary_too_late:
 	.endr
 
 secondary_nap:
+	/* Clear our vcpu pointer so we don't come back in early */
+	li	r0, 0
+	std	r0, HSTATE_KVM_VCPU(r13)
+	lwsync
 	/* Clear any pending IPI - assume we're a secondary thread */
 	ld	r5, HSTATE_XICS_PHYS(r13)
 	li	r7, XICS_XIRR
@@ -1612,8 +1619,6 @@ secondary_nap:
 kvm_no_guest:
 	li	r0, KVM_HWTHREAD_IN_NAP
 	stb	r0, HSTATE_HWTHREAD_STATE(r13)
-	li	r0, 0
-	std	r0, HSTATE_KVM_VCPU(r13)
 
 	li	r3, LPCR_PECE0
 	mfspr	r4, SPRN_LPCR
-- 
1.7.10.4

[PATCH 3/8] KVM: PPC: Book3s HV: Don't access runnable threads list without vcore lock

[Paul Mackerras]

There were a few places where we were traversing the list of runnable
threads in a virtual core, i.e. vc->runnable_threads, without holding
the vcore spinlock.  This extends the places where we hold the vcore
spinlock to cover everywhere that we traverse that list.

Since we possibly need to sleep inside kvmppc_book3s_hv_page_fault,
this moves the call of it from kvmppc_handle_exit out to
kvmppc_vcpu_run, where we don't hold the vcore lock.

In kvmppc_vcore_blocked, we don't actually need to check whether
all vcpus are ceded and don't have any pending exceptions, since the
caller has already done that.  The caller (kvmppc_run_vcpu) wasn't
actually checking for pending exceptions, so we add that.

The change of if to while in kvmppc_run_vcpu is to make sure that we
never call kvmppc_remove_runnable() when the vcore state is RUNNING or
EXITING.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/include/asm/kvm_asm.h |    1 +
 arch/powerpc/kvm/book3s_hv.c       |   67 ++++++++++++++++++------------------
 2 files changed, 34 insertions(+), 34 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_asm.h b/arch/powerpc/include/asm/kvm_asm.h
index 76fdcfe..aabcdba 100644
--- a/arch/powerpc/include/asm/kvm_asm.h
+++ b/arch/powerpc/include/asm/kvm_asm.h
@@ -118,6 +118,7 @@
 
 #define RESUME_FLAG_NV          (1<<0)  /* Reload guest nonvolatile state? */
 #define RESUME_FLAG_HOST        (1<<1)  /* Resume host? */
+#define RESUME_FLAG_ARCH1	(1<<2)
 
 #define RESUME_GUEST            0
 #define RESUME_GUEST_NV         RESUME_FLAG_NV
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 77dec0f..3a737a4 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -57,6 +57,9 @@
 /* #define EXIT_DEBUG_SIMPLE */
 /* #define EXIT_DEBUG_INT */
 
+/* Used to indicate that a guest page fault needs to be handled */
+#define RESUME_PAGE_FAULT	(RESUME_GUEST | RESUME_FLAG_ARCH1)
+
 static void kvmppc_end_cede(struct kvm_vcpu *vcpu);
 static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu);
 
@@ -431,7 +434,6 @@ static int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			      struct task_struct *tsk)
 {
 	int r = RESUME_HOST;
-	int srcu_idx;
 
 	vcpu->stat.sum_exits++;
 
@@ -491,16 +493,12 @@ static int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 	 * have been handled already.
 	 */
 	case BOOK3S_INTERRUPT_H_DATA_STORAGE:
-		srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
-		r = kvmppc_book3s_hv_page_fault(run, vcpu,
-				vcpu->arch.fault_dar, vcpu->arch.fault_dsisr);
-		srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx);
+		r = RESUME_PAGE_FAULT;
 		break;
 	case BOOK3S_INTERRUPT_H_INST_STORAGE:
-		srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
-		r = kvmppc_book3s_hv_page_fault(run, vcpu,
-				kvmppc_get_pc(vcpu), 0);
-		srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx);
+		vcpu->arch.fault_dar = kvmppc_get_pc(vcpu);
+		vcpu->arch.fault_dsisr = 0;
+		r = RESUME_PAGE_FAULT;
 		break;
 	/*
 	 * This occurs if the guest executes an illegal instruction.
@@ -984,22 +982,24 @@ static int on_primary_thread(void)
  * Run a set of guest threads on a physical core.
  * Called with vc->lock held.
  */
-static int kvmppc_run_core(struct kvmppc_vcore *vc)
+static void kvmppc_run_core(struct kvmppc_vcore *vc)
 {
 	struct kvm_vcpu *vcpu, *vcpu0, *vnext;
 	long ret;
 	u64 now;
 	int ptid, i, need_vpa_update;
 	int srcu_idx;
+	struct kvm_vcpu *vcpus_to_update[threads_per_core];
 
 	/* don't start if any threads have a signal pending */
 	need_vpa_update = 0;
 	list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) {
 		if (signal_pending(vcpu->arch.run_task))
-			return 0;
-		need_vpa_update |= vcpu->arch.vpa.update_pending |
-			vcpu->arch.slb_shadow.update_pending |
-			vcpu->arch.dtl.update_pending;
+			return;
+		if (vcpu->arch.vpa.update_pending ||
+		    vcpu->arch.slb_shadow.update_pending ||
+		    vcpu->arch.dtl.update_pending)
+			vcpus_to_update[need_vpa_update++] = vcpu;
 	}
 
 	/*
@@ -1019,8 +1019,8 @@ static int kvmppc_run_core(struct kvmppc_vcore *vc)
 	 */
 	if (need_vpa_update) {
 		spin_unlock(&vc->lock);
-		list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list)
-			kvmppc_update_vpas(vcpu);
+		for (i = 0; i < need_vpa_update; ++i)
+			kvmppc_update_vpas(vcpus_to_update[i]);
 		spin_lock(&vc->lock);
 	}
 
@@ -1037,8 +1037,10 @@ static int kvmppc_run_core(struct kvmppc_vcore *vc)
 			vcpu->arch.ptid = ptid++;
 		}
 	}
-	if (!vcpu0)
-		return 0;		/* nothing to run */
+	if (!vcpu0) {
+		vc->vcore_state = VCORE_INACTIVE;
+		return;		/* nothing to run; should never happen */
+	}
 	list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list)
 		if (vcpu->arch.ceded)
 			vcpu->arch.ptid = ptid++;
@@ -1091,6 +1093,7 @@ static int kvmppc_run_core(struct kvmppc_vcore *vc)
 	preempt_enable();
 	kvm_resched(vcpu);
 
+	spin_lock(&vc->lock);
 	now = get_tb();
 	list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) {
 		/* cancel pending dec exception if dec is positive */
@@ -1114,7 +1117,6 @@ static int kvmppc_run_core(struct kvmppc_vcore *vc)
 		}
 	}
 
-	spin_lock(&vc->lock);
  out:
 	vc->vcore_state = VCORE_INACTIVE;
 	vc->preempt_tb = mftb();
@@ -1125,8 +1127,6 @@ static int kvmppc_run_core(struct kvmppc_vcore *vc)
 			wake_up(&vcpu->arch.cpu_run);
 		}
 	}
-
-	return 1;
 }
 
 /*
@@ -1150,20 +1150,11 @@ static void kvmppc_wait_for_exec(struct kvm_vcpu *vcpu, int wait_state)
 static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)
 {
 	DEFINE_WAIT(wait);
-	struct kvm_vcpu *v;
-	int all_idle = 1;
 
 	prepare_to_wait(&vc->wq, &wait, TASK_INTERRUPTIBLE);
 	vc->vcore_state = VCORE_SLEEPING;
 	spin_unlock(&vc->lock);
-	list_for_each_entry(v, &vc->runnable_threads, arch.run_list) {
-		if (!v->arch.ceded || v->arch.pending_exceptions) {
-			all_idle = 0;
-			break;
-		}
-	}
-	if (all_idle)
-		schedule();
+	schedule();
 	finish_wait(&vc->wq, &wait);
 	spin_lock(&vc->lock);
 	vc->vcore_state = VCORE_INACTIVE;
@@ -1219,7 +1210,8 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 		vc->runner = vcpu;
 		n_ceded = 0;
 		list_for_each_entry(v, &vc->runnable_threads, arch.run_list)
-			n_ceded += v->arch.ceded;
+			if (!v->arch.pending_exceptions)
+				n_ceded += v->arch.ceded;
 		if (n_ceded == vc->n_runnable)
 			kvmppc_vcore_blocked(vc);
 		else
@@ -1240,8 +1232,9 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 	}
 
 	if (signal_pending(current)) {
-		if (vc->vcore_state == VCORE_RUNNING ||
-		    vc->vcore_state == VCORE_EXITING) {
+		while (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE &&
+		       (vc->vcore_state == VCORE_RUNNING ||
+			vc->vcore_state == VCORE_EXITING)) {
 			spin_unlock(&vc->lock);
 			kvmppc_wait_for_exec(vcpu, TASK_UNINTERRUPTIBLE);
 			spin_lock(&vc->lock);
@@ -1261,6 +1254,7 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 int kvmppc_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu)
 {
 	int r;
+	int srcu_idx;
 
 	if (!vcpu->arch.sane) {
 		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
@@ -1299,6 +1293,11 @@ int kvmppc_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu)
 		    !(vcpu->arch.shregs.msr & MSR_PR)) {
 			r = kvmppc_pseries_do_hcall(vcpu);
 			kvmppc_core_prepare_to_enter(vcpu);
+		} else if (r == RESUME_PAGE_FAULT) {
+			srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+			r = kvmppc_book3s_hv_page_fault(run, vcpu,
+				vcpu->arch.fault_dar, vcpu->arch.fault_dsisr);
+			srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx);
 		}
 	} while (r == RESUME_GUEST);
 
-- 
1.7.10.4

[PATCH 4/8] KVM: PPC: Book3S HV: Fixes for late-joining threads

[Paul Mackerras]

If a thread in a virtual core becomes runnable while other threads
in the same virtual core are already running in the guest, it is
possible for the latecomer to join the others on the core without
first pulling them all out of the guest.  Currently this only happens
rarely, when a vcpu is first started.  This fixes some bugs and
omissions in the code in this case.

First, we need to check for VPA updates for the latecomer and make
a DTL entry for it.  Secondly, if it comes along while the master
vcpu is doing a VPA update, we don't need to do anything since the
master will pick it up in kvmppc_run_core.  To handle this correctly
we introduce a new vcore state, VCORE_STARTING.  Thirdly, there is
a race because we currently clear the hardware thread's hwthread_req
before waiting to see it get to nap.  A latecomer thread could have
its hwthread_req cleared before it gets to test it, and therefore
never increment the nap_count, leading to messages about wait_for_nap
timeouts.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/include/asm/kvm_host.h |    7 ++++---
 arch/powerpc/kvm/book3s_hv.c        |   14 +++++++++++---
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 68f5a30..218534d 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -289,9 +289,10 @@ struct kvmppc_vcore {
 
 /* Values for vcore_state */
 #define VCORE_INACTIVE	0
-#define VCORE_RUNNING	1
-#define VCORE_EXITING	2
-#define VCORE_SLEEPING	3
+#define VCORE_SLEEPING	1
+#define VCORE_STARTING	2
+#define VCORE_RUNNING	3
+#define VCORE_EXITING	4
 
 /*
  * Struct used to manage memory for a virtual processor area
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 3a737a4..89995fa 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -336,6 +336,11 @@ static void kvmppc_update_vpa(struct kvm_vcpu *vcpu, struct kvmppc_vpa *vpap)
 
 static void kvmppc_update_vpas(struct kvm_vcpu *vcpu)
 {
+	if (!(vcpu->arch.vpa.update_pending ||
+	      vcpu->arch.slb_shadow.update_pending ||
+	      vcpu->arch.dtl.update_pending))
+		return;
+
 	spin_lock(&vcpu->arch.vpa_update_lock);
 	if (vcpu->arch.vpa.update_pending) {
 		kvmppc_update_vpa(vcpu, &vcpu->arch.vpa);
@@ -1009,7 +1014,7 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
 	vc->n_woken = 0;
 	vc->nap_count = 0;
 	vc->entry_exit_count = 0;
-	vc->vcore_state = VCORE_RUNNING;
+	vc->vcore_state = VCORE_STARTING;
 	vc->in_guest = 0;
 	vc->napping_threads = 0;
 
@@ -1062,6 +1067,7 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
 		kvmppc_create_dtl_entry(vcpu, vc);
 	}
 
+	vc->vcore_state = VCORE_RUNNING;
 	preempt_disable();
 	spin_unlock(&vc->lock);
 
@@ -1070,8 +1076,6 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
 	srcu_idx = srcu_read_lock(&vcpu0->kvm->srcu);
 
 	__kvmppc_vcore_entry(NULL, vcpu0);
-	for (i = 0; i < threads_per_core; ++i)
-		kvmppc_release_hwthread(vc->pcpu + i);
 
 	spin_lock(&vc->lock);
 	/* disable sending of IPIs on virtual external irqs */
@@ -1080,6 +1084,8 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
 	/* wait for secondary threads to finish writing their state to memory */
 	if (vc->nap_count < vc->n_woken)
 		kvmppc_wait_for_nap(vc);
+	for (i = 0; i < threads_per_core; ++i)
+		kvmppc_release_hwthread(vc->pcpu + i);
 	/* prevent other vcpu threads from doing kvmppc_start_thread() now */
 	vc->vcore_state = VCORE_EXITING;
 	spin_unlock(&vc->lock);
@@ -1170,6 +1176,7 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 	kvm_run->exit_reason = 0;
 	vcpu->arch.ret = RESUME_GUEST;
 	vcpu->arch.trap = 0;
+	kvmppc_update_vpas(vcpu);
 
 	/*
 	 * Synchronize with other threads in this virtual core
@@ -1193,6 +1200,7 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 		if (vc->vcore_state == VCORE_RUNNING &&
 		    VCORE_EXIT_COUNT(vc) == 0) {
 			vcpu->arch.ptid = vc->n_runnable - 1;
+			kvmppc_create_dtl_entry(vcpu, vc);
 			kvmppc_start_thread(vcpu);
 		}
 
-- 
1.7.10.4

[PATCH 5/8] KVM: PPC: Book3S HV: Run virtual core whenever any vcpus in it can run

[Paul Mackerras]

Currently the Book3S HV code implements a policy on multi-threaded
processors (i.e. POWER7) that requires all of the active vcpus in a
virtual core to be ready to run before we run the virtual core.
However, that causes problems on reset, because reset stops all vcpus
except vcpu 0, and can also reduce throughput since all four threads
in a virtual core have to wait whenever any one of them hits a
hypervisor page fault.

This relaxes the policy, allowing the virtual core to run as soon as
any vcpu in it is runnable.  With this, the KVMPPC_VCPU_STOPPED state
and the KVMPPC_VCPU_BUSY_IN_HOST state have been combined into a single
KVMPPC_VCPU_NOTREADY state, since we no longer need to distinguish
between them.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/include/asm/kvm_host.h |    5 +--
 arch/powerpc/kvm/book3s_hv.c        |   74 ++++++++++++++++++-----------------
 2 files changed, 40 insertions(+), 39 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 218534d..1e8cbd1 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -563,9 +563,8 @@ struct kvm_vcpu_arch {
 };
 
 /* Values for vcpu->arch.state */
-#define KVMPPC_VCPU_STOPPED		0
-#define KVMPPC_VCPU_BUSY_IN_HOST	1
-#define KVMPPC_VCPU_RUNNABLE		2
+#define KVMPPC_VCPU_NOTREADY		0
+#define KVMPPC_VCPU_RUNNABLE		1
 
 /* Values for vcpu->arch.io_gpr */
 #define KVM_MMIO_REG_MASK	0x001f
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 89995fa..61d2934 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -776,10 +776,7 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
 
 	kvmppc_mmu_book3s_hv_init(vcpu);
 
-	/*
-	 * We consider the vcpu stopped until we see the first run ioctl for it.
-	 */
-	vcpu->arch.state = KVMPPC_VCPU_STOPPED;
+	vcpu->arch.state = KVMPPC_VCPU_NOTREADY;
 
 	init_waitqueue_head(&vcpu->arch.cpu_run);
 
@@ -866,9 +863,8 @@ static void kvmppc_remove_runnable(struct kvmppc_vcore *vc,
 {
 	if (vcpu->arch.state != KVMPPC_VCPU_RUNNABLE)
 		return;
-	vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST;
+	vcpu->arch.state = KVMPPC_VCPU_NOTREADY;
 	--vc->n_runnable;
-	++vc->n_busy;
 	list_del(&vcpu->arch.run_list);
 }
 
@@ -1169,7 +1165,6 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)
 static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 {
 	int n_ceded;
-	int prev_state;
 	struct kvmppc_vcore *vc;
 	struct kvm_vcpu *v, *vn;
 
@@ -1186,7 +1181,6 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 	vcpu->arch.ceded = 0;
 	vcpu->arch.run_task = current;
 	vcpu->arch.kvm_run = kvm_run;
-	prev_state = vcpu->arch.state;
 	vcpu->arch.state = KVMPPC_VCPU_RUNNABLE;
 	list_add_tail(&vcpu->arch.run_list, &vc->runnable_threads);
 	++vc->n_runnable;
@@ -1196,35 +1190,26 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 	 * If the vcore is already running, we may be able to start
 	 * this thread straight away and have it join in.
 	 */
-	if (prev_state == KVMPPC_VCPU_STOPPED) {
+	if (!signal_pending(current)) {
 		if (vc->vcore_state == VCORE_RUNNING &&
 		    VCORE_EXIT_COUNT(vc) == 0) {
 			vcpu->arch.ptid = vc->n_runnable - 1;
 			kvmppc_create_dtl_entry(vcpu, vc);
 			kvmppc_start_thread(vcpu);
+		} else if (vc->vcore_state == VCORE_SLEEPING) {
+			wake_up(&vc->wq);
 		}
 
-	} else if (prev_state == KVMPPC_VCPU_BUSY_IN_HOST)
-		--vc->n_busy;
+	}
 
 	while (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE &&
 	       !signal_pending(current)) {
-		if (vc->n_busy || vc->vcore_state != VCORE_INACTIVE) {
+		if (vc->vcore_state != VCORE_INACTIVE) {
 			spin_unlock(&vc->lock);
 			kvmppc_wait_for_exec(vcpu, TASK_INTERRUPTIBLE);
 			spin_lock(&vc->lock);
 			continue;
 		}
-		vc->runner = vcpu;
-		n_ceded = 0;
-		list_for_each_entry(v, &vc->runnable_threads, arch.run_list)
-			if (!v->arch.pending_exceptions)
-				n_ceded += v->arch.ceded;
-		if (n_ceded == vc->n_runnable)
-			kvmppc_vcore_blocked(vc);
-		else
-			kvmppc_run_core(vc);
-
 		list_for_each_entry_safe(v, vn, &vc->runnable_threads,
 					 arch.run_list) {
 			kvmppc_core_prepare_to_enter(v);
@@ -1236,23 +1221,40 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 				wake_up(&v->arch.cpu_run);
 			}
 		}
+		if (!vc->n_runnable || vcpu->arch.state != KVMPPC_VCPU_RUNNABLE)
+			break;
+		vc->runner = vcpu;
+		n_ceded = 0;
+		list_for_each_entry(v, &vc->runnable_threads, arch.run_list)
+			if (!v->arch.pending_exceptions)
+				n_ceded += v->arch.ceded;
+		if (n_ceded == vc->n_runnable)
+			kvmppc_vcore_blocked(vc);
+		else
+			kvmppc_run_core(vc);
 		vc->runner = NULL;
 	}
 
-	if (signal_pending(current)) {
-		while (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE &&
-		       (vc->vcore_state == VCORE_RUNNING ||
-			vc->vcore_state == VCORE_EXITING)) {
-			spin_unlock(&vc->lock);
-			kvmppc_wait_for_exec(vcpu, TASK_UNINTERRUPTIBLE);
-			spin_lock(&vc->lock);
-		}
-		if (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE) {
-			kvmppc_remove_runnable(vc, vcpu);
-			vcpu->stat.signal_exits++;
-			kvm_run->exit_reason = KVM_EXIT_INTR;
-			vcpu->arch.ret = -EINTR;
-		}
+	while (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE &&
+	       (vc->vcore_state == VCORE_RUNNING ||
+		vc->vcore_state == VCORE_EXITING)) {
+		spin_unlock(&vc->lock);
+		kvmppc_wait_for_exec(vcpu, TASK_UNINTERRUPTIBLE);
+		spin_lock(&vc->lock);
+	}
+
+	if (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE) {
+		kvmppc_remove_runnable(vc, vcpu);
+		vcpu->stat.signal_exits++;
+		kvm_run->exit_reason = KVM_EXIT_INTR;
+		vcpu->arch.ret = -EINTR;
+	}
+
+	if (vc->n_runnable && vc->vcore_state == VCORE_INACTIVE) {
+		/* Wake up some vcpu to run the core */
+		v = list_first_entry(&vc->runnable_threads,
+				     struct kvm_vcpu, arch.run_list);
+		wake_up(&v->arch.cpu_run);
 	}
 
 	spin_unlock(&vc->lock);
-- 
1.7.10.4

[PATCH 6/8] KVM: PPC: Book3S HV: Fix accounting of stolen time

[Paul Mackerras]

Currently the code that accounts stolen time tends to overestimate the
stolen time, and will sometimes report more stolen time in a DTL
(dispatch trace log) entry than has elapsed since the last DTL entry.
This can cause guests to underflow the user or system time measured
for some tasks, leading to ridiculous CPU percentages and total runtimes
being reported by top and other utilities.

In addition, the current code was designed for the previous policy where
a vcore would only run when all the vcpus in it were runnable, and so
only counted stolen time on a per-vcore basis.  Now that a vcore can
run while some of the vcpus in it are doing other things in the kernel
(e.g. handling a page fault), we need to count the time when a vcpu task
is preempted while it is not running as part of a vcore as stolen also.

To do this, we bring back the BUSY_IN_HOST vcpu state and extend the
vcpu_load/put functions to count preemption time while the vcpu is
in that state.  Handling the transitions between the RUNNING and
BUSY_IN_HOST states requires checking and updating two variables
(accumulated time stolen and time last preempted), so we add a new
spinlock, vcpu->arch.tbacct_lock.  This protects both the per-vcpu
stolen/preempt-time variables, and the per-vcore variables while this
vcpu is running the vcore.

Finally, we now don't count time spent in userspace as stolen time.
The task could be executing in userspace on behalf of the vcpu, or
it could be preempted, or the vcpu could be genuinely stopped.  Since
we have no way of dividing up the time between these cases, we don't
count any of it as stolen.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/include/asm/kvm_host.h |    5 ++
 arch/powerpc/kvm/book3s_hv.c        |  127 ++++++++++++++++++++++++++++++-----
 2 files changed, 117 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 1e8cbd1..3093896 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -559,12 +559,17 @@ struct kvm_vcpu_arch {
 	unsigned long dtl_index;
 	u64 stolen_logged;
 	struct kvmppc_vpa slb_shadow;
+
+	spinlock_t tbacct_lock;
+	u64 busy_stolen;
+	u64 busy_preempt;
 #endif
 };
 
 /* Values for vcpu->arch.state */
 #define KVMPPC_VCPU_NOTREADY		0
 #define KVMPPC_VCPU_RUNNABLE		1
+#define KVMPPC_VCPU_BUSY_IN_HOST	2
 
 /* Values for vcpu->arch.io_gpr */
 #define KVM_MMIO_REG_MASK	0x001f
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 61d2934..8b3c470 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -60,23 +60,74 @@
 /* Used to indicate that a guest page fault needs to be handled */
 #define RESUME_PAGE_FAULT	(RESUME_GUEST | RESUME_FLAG_ARCH1)
 
+/* Used as a "null" value for timebase values */
+#define TB_NIL	(~(u64)0)
+
 static void kvmppc_end_cede(struct kvm_vcpu *vcpu);
 static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu);
 
+/*
+ * We use the vcpu_load/put functions to measure stolen time.
+ * Stolen time is counted as time when either the vcpu is able to
+ * run as part of a virtual core, but the task running the vcore
+ * is preempted or sleeping, or when the vcpu needs something done
+ * in the kernel by the task running the vcpu, but that task is
+ * preempted or sleeping.  Those two things have to be counted
+ * separately, since one of the vcpu tasks will take on the job
+ * of running the core, and the other vcpu tasks in the vcore will
+ * sleep waiting for it to do that, but that sleep shouldn't count
+ * as stolen time.
+ *
+ * Hence we accumulate stolen time when the vcpu can run as part of
+ * a vcore using vc->stolen_tb, and the stolen time when the vcpu
+ * needs its task to do other things in the kernel (for example,
+ * service a page fault) in busy_stolen.  We don't accumulate
+ * stolen time for a vcore when it is inactive, or for a vcpu
+ * when it is in state RUNNING or NOTREADY.  NOTREADY is a bit of
+ * a misnomer; it means that the vcpu task is not executing in
+ * the KVM_VCPU_RUN ioctl, i.e. it is in userspace or elsewhere in
+ * the kernel.  We don't have any way of dividing up that time
+ * between time that the vcpu is genuinely stopped, time that
+ * the task is actively working on behalf of the vcpu, and time
+ * that the task is preempted, so we don't count any of it as
+ * stolen.
+ *
+ * Updates to busy_stolen are protected by arch.tbacct_lock;
+ * updates to vc->stolen_tb are protected by the arch.tbacct_lock
+ * of the vcpu that has taken responsibility for running the vcore
+ * (i.e. vc->runner).  The stolen times are measured in units of
+ * timebase ticks.  (Note that the != TB_NIL checks below are
+ * purely defensive; they should never fail.)
+ */
+
 void kvmppc_core_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
 	struct kvmppc_vcore *vc = vcpu->arch.vcore;
 
-	if (vc->runner == vcpu && vc->vcore_state != VCORE_INACTIVE)
+	spin_lock(&vcpu->arch.tbacct_lock);
+	if (vc->runner == vcpu && vc->vcore_state != VCORE_INACTIVE &&
+	    vc->preempt_tb != TB_NIL) {
 		vc->stolen_tb += mftb() - vc->preempt_tb;
+		vc->preempt_tb = TB_NIL;
+	}
+	if (vcpu->arch.state == KVMPPC_VCPU_BUSY_IN_HOST &&
+	    vcpu->arch.busy_preempt != TB_NIL) {
+		vcpu->arch.busy_stolen += mftb() - vcpu->arch.busy_preempt;
+		vcpu->arch.busy_preempt = TB_NIL;
+	}
+	spin_unlock(&vcpu->arch.tbacct_lock);
 }
 
 void kvmppc_core_vcpu_put(struct kvm_vcpu *vcpu)
 {
 	struct kvmppc_vcore *vc = vcpu->arch.vcore;
 
+	spin_lock(&vcpu->arch.tbacct_lock);
 	if (vc->runner == vcpu && vc->vcore_state != VCORE_INACTIVE)
 		vc->preempt_tb = mftb();
+	if (vcpu->arch.state == KVMPPC_VCPU_BUSY_IN_HOST)
+		vcpu->arch.busy_preempt = mftb();
+	spin_unlock(&vcpu->arch.tbacct_lock);
 }
 
 void kvmppc_set_msr(struct kvm_vcpu *vcpu, u64 msr)
@@ -357,24 +408,61 @@ static void kvmppc_update_vpas(struct kvm_vcpu *vcpu)
 	spin_unlock(&vcpu->arch.vpa_update_lock);
 }
 
+/*
+ * Return the accumulated stolen time for the vcore up until `now'.
+ * The caller should hold the vcore lock.
+ */
+static u64 vcore_stolen_time(struct kvmppc_vcore *vc, u64 now)
+{
+	u64 p;
+
+	/*
+	 * If we are the task running the vcore, then since we hold
+	 * the vcore lock, we can't be preempted, so stolen_tb/preempt_tb
+	 * can't be updated, so we don't need the tbacct_lock.
+	 * If the vcore is inactive, it can't become active (since we
+	 * hold the vcore lock), so the vcpu load/put functions won't
+	 * update stolen_tb/preempt_tb, and we don't need tbacct_lock.
+	 */
+	if (vc->vcore_state != VCORE_INACTIVE &&
+	    vc->runner->arch.run_task != current) {
+		spin_lock(&vc->runner->arch.tbacct_lock);
+		p = vc->stolen_tb;
+		if (vc->preempt_tb != TB_NIL)
+			p += now - vc->preempt_tb;
+		spin_unlock(&vc->runner->arch.tbacct_lock);
+	} else {
+		p = vc->stolen_tb;
+	}
+	return p;
+}
+
 static void kvmppc_create_dtl_entry(struct kvm_vcpu *vcpu,
 				    struct kvmppc_vcore *vc)
 {
 	struct dtl_entry *dt;
 	struct lppaca *vpa;
-	unsigned long old_stolen;
+	unsigned long stolen;
+	unsigned long core_stolen;
+	u64 now;
 
 	dt = vcpu->arch.dtl_ptr;
 	vpa = vcpu->arch.vpa.pinned_addr;
-	old_stolen = vcpu->arch.stolen_logged;
-	vcpu->arch.stolen_logged = vc->stolen_tb;
+	now = mftb();
+	core_stolen = vcore_stolen_time(vc, now);
+	stolen = core_stolen - vcpu->arch.stolen_logged;
+	vcpu->arch.stolen_logged = core_stolen;
+	spin_lock(&vcpu->arch.tbacct_lock);
+	stolen += vcpu->arch.busy_stolen;
+	vcpu->arch.busy_stolen = 0;
+	spin_unlock(&vcpu->arch.tbacct_lock);
 	if (!dt || !vpa)
 		return;
 	memset(dt, 0, sizeof(struct dtl_entry));
 	dt->dispatch_reason = 7;
 	dt->processor_id = vc->pcpu + vcpu->arch.ptid;
-	dt->timebase = mftb();
-	dt->enqueue_to_dispatch_time = vc->stolen_tb - old_stolen;
+	dt->timebase = now;
+	dt->enqueue_to_dispatch_time = stolen;
 	dt->srr0 = kvmppc_get_pc(vcpu);
 	dt->srr1 = vcpu->arch.shregs.msr;
 	++dt;
@@ -773,6 +861,8 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
 	vcpu->arch.pvr = mfspr(SPRN_PVR);
 	kvmppc_set_pvr(vcpu, vcpu->arch.pvr);
 	spin_lock_init(&vcpu->arch.vpa_update_lock);
+	spin_lock_init(&vcpu->arch.tbacct_lock);
+	vcpu->arch.busy_preempt = TB_NIL;
 
 	kvmppc_mmu_book3s_hv_init(vcpu);
 
@@ -788,7 +878,7 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
 			INIT_LIST_HEAD(&vcore->runnable_threads);
 			spin_lock_init(&vcore->lock);
 			init_waitqueue_head(&vcore->wq);
-			vcore->preempt_tb = mftb();
+			vcore->preempt_tb = TB_NIL;
 		}
 		kvm->arch.vcores[core] = vcore;
 	}
@@ -801,7 +891,6 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
 	++vcore->num_threads;
 	spin_unlock(&vcore->lock);
 	vcpu->arch.vcore = vcore;
-	vcpu->arch.stolen_logged = vcore->stolen_tb;
 
 	vcpu->arch.cpu_type = KVM_CPU_3S_64;
 	kvmppc_sanity_check(vcpu);
@@ -861,9 +950,17 @@ extern void xics_wake_cpu(int cpu);
 static void kvmppc_remove_runnable(struct kvmppc_vcore *vc,
 				   struct kvm_vcpu *vcpu)
 {
+	u64 now;
+
 	if (vcpu->arch.state != KVMPPC_VCPU_RUNNABLE)
 		return;
-	vcpu->arch.state = KVMPPC_VCPU_NOTREADY;
+	spin_lock(&vcpu->arch.tbacct_lock);
+	now = mftb();
+	vcpu->arch.busy_stolen += vcore_stolen_time(vc, now) -
+		vcpu->arch.stolen_logged;
+	vcpu->arch.busy_preempt = now;
+	vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST;
+	spin_unlock(&vcpu->arch.tbacct_lock);
 	--vc->n_runnable;
 	list_del(&vcpu->arch.run_list);
 }
@@ -1038,10 +1135,8 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
 			vcpu->arch.ptid = ptid++;
 		}
 	}
-	if (!vcpu0) {
-		vc->vcore_state = VCORE_INACTIVE;
-		return;		/* nothing to run; should never happen */
-	}
+	if (!vcpu0)
+		goto out;	/* nothing to run; should never happen */
 	list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list)
 		if (vcpu->arch.ceded)
 			vcpu->arch.ptid = ptid++;
@@ -1056,7 +1151,6 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
 		goto out;
 	}
 
-	vc->stolen_tb += mftb() - vc->preempt_tb;
 	vc->pcpu = smp_processor_id();
 	list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) {
 		kvmppc_start_thread(vcpu);
@@ -1121,7 +1215,6 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
 
  out:
 	vc->vcore_state = VCORE_INACTIVE;
-	vc->preempt_tb = mftb();
 	list_for_each_entry_safe(vcpu, vnext, &vc->runnable_threads,
 				 arch.run_list) {
 		if (vcpu->arch.ret != RESUME_GUEST) {
@@ -1181,7 +1274,9 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 	vcpu->arch.ceded = 0;
 	vcpu->arch.run_task = current;
 	vcpu->arch.kvm_run = kvm_run;
+	vcpu->arch.stolen_logged = vcore_stolen_time(vc, mftb());
 	vcpu->arch.state = KVMPPC_VCPU_RUNNABLE;
+	vcpu->arch.busy_preempt = TB_NIL;
 	list_add_tail(&vcpu->arch.run_list, &vc->runnable_threads);
 	++vc->n_runnable;
 
@@ -1295,6 +1390,7 @@ int kvmppc_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu)
 	flush_vsx_to_thread(current);
 	vcpu->arch.wqp = &vcpu->arch.vcore->wq;
 	vcpu->arch.pgdir = current->mm->pgd;
+	vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST;
 
 	do {
 		r = kvmppc_run_vcpu(run, vcpu);
@@ -1312,6 +1408,7 @@ int kvmppc_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu)
 	} while (r == RESUME_GUEST);
 
  out:
+	vcpu->arch.state = KVMPPC_VCPU_NOTREADY;
 	atomic_dec(&vcpu->kvm->arch.vcpus_running);
 	return r;
 }
-- 
1.7.10.4

[PATCH 7/8] KVM: PPC: Book3S HV: Allow DTL to be set to address 0, length 0

[Paul Mackerras]

Commit 55b665b026 ("KVM: PPC: Book3S HV: Provide a way for userspace
to get/set per-vCPU areas") includes a check on the length of the
dispatch trace log (DTL) to make sure the buffer is at least one entry
long.  This is appropriate when registering a buffer, but the
interface also allows for any existing buffer to be unregistered by
specifying a zero address.  In this case the length check is not
appropriate.  This makes the check conditional on the address being
non-zero.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/kvm/book3s_hv.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 8b3c470..812764c 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -811,9 +811,8 @@ int kvmppc_set_one_reg(struct kvm_vcpu *vcpu, u64 id, union kvmppc_one_reg *val)
 		addr = val->vpaval.addr;
 		len = val->vpaval.length;
 		r = -EINVAL;
-		if (len < sizeof(struct dtl_entry))
-			break;
-		if (addr && !vcpu->arch.vpa.next_gpa)
+		if (addr && (len < sizeof(struct dtl_entry) ||
+			     !vcpu->arch.vpa.next_gpa))
 			break;
 		len -= len % sizeof(struct dtl_entry);
 		r = set_vpa(vcpu, &vcpu->arch.dtl, addr, len);
-- 
1.7.10.4

[PATCH 8/8] KVM: PPC: Book3S HV: Fix thinko in try_lock_hpte()

[Paul Mackerras]

This fixes an error in the inline asm in try_lock_hpte() where we
were erroneously using a register number as an immediate operand.
The bug only affects an error path, and in fact the code will still
work as long as the compiler chooses some register other than r0
for the "bits" variable.  Nevertheless it should still be fixed.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/include/asm/kvm_book3s_64.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index 0dd1d86..1472a5b 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -60,7 +60,7 @@ static inline long try_lock_hpte(unsigned long *hpte, unsigned long bits)
 		     "	ori	%0,%0,%4\n"
 		     "  stdcx.	%0,0,%2\n"
 		     "	beq+	2f\n"
-		     "	li	%1,%3\n"
+		     "	mr	%1,%3\n"
 		     "2:	isync"
 		     : "=&r" (tmp), "=&r" (old)
 		     : "r" (hpte), "r" (bits), "i" (HPTE_V_HVLOCK)
-- 
1.7.10.4