Patchwork [2/2,v3] KVM: PPC: booke: Add watchdog emulation

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Submitter Bharat Bhushan
Date July 18, 2012, 9:36 a.m.
Message ID <1342604174-22534-1-git-send-email-Bharat.Bhushan@freescale.com>
Download mbox | patch
Permalink /patch/171616/
State New
Headers show

Comments

Bharat Bhushan - July 18, 2012, 9:36 a.m.
This patch adds the watchdog emulation in KVM. The watchdog
emulation is enabled by KVM_ENABLE_CAP(KVM_CAP_PPC_WDT) ioctl.
The kernel timer are used for watchdog emulation and emulates
h/w watchdog state machine. On watchdog timer expiry, it exit to QEMU
if TCR.WRC is non ZERO. QEMU can reset/shutdown etc depending upon how
it is configured.

Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
---
v3:
 - Using KVM_REQ_WATCHDOG for userspace exit.
 - TSR changes left for vcpu thread.
 - Other review comments on v2

 arch/powerpc/include/asm/kvm_host.h  |    3 +
 arch/powerpc/include/asm/kvm_ppc.h   |    3 +
 arch/powerpc/include/asm/reg_booke.h |    7 ++
 arch/powerpc/kvm/booke.c             |  140 ++++++++++++++++++++++++++++++++++
 arch/powerpc/kvm/booke_emulate.c     |    8 ++
 arch/powerpc/kvm/powerpc.c           |   27 ++++++-
 include/linux/kvm.h                  |    2 +
 include/linux/kvm_host.h             |    1 +
 8 files changed, 187 insertions(+), 4 deletions(-)

Patch

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 50ea12f..01047f4 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -467,6 +467,8 @@  struct kvm_vcpu_arch {
 	ulong fault_esr;
 	ulong queued_dear;
 	ulong queued_esr;
+	spinlock_t wdt_lock;
+	struct timer_list wdt_timer;
 	u32 tlbcfg[4];
 	u32 mmucfg;
 	u32 epr;
@@ -482,6 +484,7 @@  struct kvm_vcpu_arch {
 	u8 osi_needed;
 	u8 osi_enabled;
 	u8 papr_enabled;
+	u8 watchdog_enable;
 	u8 sane;
 	u8 cpu_type;
 	u8 hcall_needed;
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 0124937..e5cf4b9 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -67,6 +67,7 @@  extern int kvmppc_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu);
 extern void kvmppc_emulate_dec(struct kvm_vcpu *vcpu);
 extern u32 kvmppc_get_dec(struct kvm_vcpu *vcpu, u64 tb);
 extern void kvmppc_decrementer_func(unsigned long data);
+extern void kvmppc_watchdog_func(unsigned long data);
 extern int kvmppc_sanity_check(struct kvm_vcpu *vcpu);
 
 /* Core-specific hooks */
@@ -104,6 +105,8 @@  extern void kvmppc_core_queue_external(struct kvm_vcpu *vcpu,
                                        struct kvm_interrupt *irq);
 extern void kvmppc_core_dequeue_external(struct kvm_vcpu *vcpu,
                                          struct kvm_interrupt *irq);
+extern void kvmppc_core_queue_watchdog(struct kvm_vcpu *vcpu);
+extern void kvmppc_core_dequeue_watchdog(struct kvm_vcpu *vcpu);
 
 extern int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
                                   unsigned int op, int *advance);
diff --git a/arch/powerpc/include/asm/reg_booke.h b/arch/powerpc/include/asm/reg_booke.h
index 2d916c4..e07e6af 100644
--- a/arch/powerpc/include/asm/reg_booke.h
+++ b/arch/powerpc/include/asm/reg_booke.h
@@ -539,6 +539,13 @@ 
 #define TCR_FIE		0x00800000	/* FIT Interrupt Enable */
 #define TCR_ARE		0x00400000	/* Auto Reload Enable */
 
+#ifdef CONFIG_E500
+#define TCR_GET_WP(tcr)  ((((tcr) & 0xC0000000) >> 30) | \
+			      (((tcr) & 0x1E0000) >> 15))
+#else
+#define TCR_GET_WP(tcr)  (((tcr) & 0xC0000000) >> 30)
+#endif
+
 /* Bit definitions for the TSR. */
 #define TSR_ENW		0x80000000	/* Enable Next Watchdog */
 #define TSR_WIS		0x40000000	/* WDT Interrupt Status */
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index d25a097..9682506 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -206,6 +206,16 @@  void kvmppc_core_dequeue_external(struct kvm_vcpu *vcpu,
 	clear_bit(BOOKE_IRQPRIO_EXTERNAL_LEVEL, &vcpu->arch.pending_exceptions);
 }
 
+void kvmppc_core_queue_watchdog(struct kvm_vcpu *vcpu)
+{
+	kvmppc_booke_queue_irqprio(vcpu, BOOKE_IRQPRIO_WATCHDOG);
+}
+
+void kvmppc_core_dequeue_watchdog(struct kvm_vcpu *vcpu)
+{
+	clear_bit(BOOKE_IRQPRIO_WATCHDOG, &vcpu->arch.pending_exceptions);
+}
+
 static void set_guest_srr(struct kvm_vcpu *vcpu, unsigned long srr0, u32 srr1)
 {
 #ifdef CONFIG_KVM_BOOKE_HV
@@ -325,6 +335,7 @@  static int kvmppc_booke_irqprio_deliver(struct kvm_vcpu *vcpu,
 		msr_mask = MSR_CE | MSR_ME | MSR_DE;
 		int_class = INT_CLASS_NONCRIT;
 		break;
+	case BOOKE_IRQPRIO_WATCHDOG:
 	case BOOKE_IRQPRIO_CRITICAL:
 	case BOOKE_IRQPRIO_DBELL_CRIT:
 		allowed = vcpu->arch.shared->msr & MSR_CE;
@@ -404,12 +415,112 @@  static int kvmppc_booke_irqprio_deliver(struct kvm_vcpu *vcpu,
 	return allowed;
 }
 
+/*
+ * Return the number of jiffies until the next timeout.  If the timeout is
+ * longer than the NEXT_TIMER_MAX_DELTA, then return NEXT_TIMER_MAX_DELTA
+ * because the larger value can break the timer APIs.
+ */
+static unsigned long watchdog_next_timeout(struct kvm_vcpu *vcpu)
+{
+	u64 tb, wdt_tb, wdt_ticks = 0;
+	u64 nr_jiffies = 0;
+	u32 period = TCR_GET_WP(vcpu->arch.tcr);
+
+	wdt_tb = 1ULL << (63 - period);
+	tb = get_tb();
+	/*
+	 * The watchdog timeout will hapeen when TB bit corresponding
+	 * to watchdog will toggle from 0 to 1.
+	 */
+	if (tb & wdt_tb)
+		wdt_ticks = wdt_tb;
+
+	wdt_ticks += wdt_tb - (tb & (wdt_tb - 1));
+
+	/* Convert timebase ticks to jiffies */
+	nr_jiffies = wdt_ticks;
+
+	if (do_div(nr_jiffies, tb_ticks_per_jiffy))
+		nr_jiffies++;
+
+	return min_t(unsigned long long, nr_jiffies, NEXT_TIMER_MAX_DELTA);
+}
+
+static void arm_next_watchdog(struct kvm_vcpu *vcpu)
+{
+	unsigned long nr_jiffies;
+
+	nr_jiffies = watchdog_next_timeout(vcpu);
+	spin_lock(&vcpu->arch.wdt_lock);
+	/*
+	 * If the number of jiffies of watchdog timer >= NEXT_TIMER_MAX_DELTA
+	 * then do not run the watchdog timer as this can break timer APIs.
+	 */
+	if (nr_jiffies < NEXT_TIMER_MAX_DELTA)
+		mod_timer(&vcpu->arch.wdt_timer, jiffies + nr_jiffies);
+	else
+		del_timer(&vcpu->arch.wdt_timer);
+	spin_unlock(&vcpu->arch.wdt_lock);
+}
+
+void kvmppc_watchdog_func(unsigned long data)
+{
+	struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
+	u32 tsr, new_tsr;
+	int final;
+
+	do {
+		new_tsr = tsr = vcpu->arch.tsr;
+		final = 0;
+
+		/* Time out event */
+		if (tsr & TSR_ENW) {
+			if (tsr & TSR_WIS) {
+				final = 1;
+			} else {
+				new_tsr = tsr | TSR_WIS;
+			}
+		} else {
+			new_tsr = tsr | TSR_ENW;
+		}
+	} while (cmpxchg(&vcpu->arch.tsr, tsr, new_tsr) != tsr);
+
+	if (new_tsr & TSR_WIS) {
+		smp_wmb();
+		kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu);
+		kvm_vcpu_kick(vcpu);
+	}
+
+	/*
+	 * If this is final watchdog expiry and some action is required
+	 * then exit to userspace.
+	 */
+	if (final && (vcpu->arch.tcr & TCR_WRC_MASK)) {
+		smp_wmb();
+		kvm_make_request(KVM_REQ_WATCHDOG, vcpu);
+		kvm_vcpu_kick(vcpu);
+	}
+
+	/*
+	 * Stop running the watchdog timer after final expiration to
+	 * prevent the host from being flooded with timers if the
+	 * guest sets a short period.
+	 * Timers will resume when TSR/TCR is updated next time.
+	 */
+	if (!final)
+		arm_next_watchdog(vcpu);
+}
 static void update_timer_ints(struct kvm_vcpu *vcpu)
 {
 	if ((vcpu->arch.tcr & TCR_DIE) && (vcpu->arch.tsr & TSR_DIS))
 		kvmppc_core_queue_dec(vcpu);
 	else
 		kvmppc_core_dequeue_dec(vcpu);
+
+	if ((vcpu->arch.tcr & TCR_WIE) && (vcpu->arch.tsr & TSR_WIS))
+		kvmppc_core_queue_watchdog(vcpu);
+	else
+		kvmppc_core_dequeue_watchdog(vcpu);
 }
 
 static void kvmppc_core_check_exceptions(struct kvm_vcpu *vcpu)
@@ -516,6 +627,13 @@  int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 		goto out;
 	}
 
+	if (kvm_check_request(KVM_REQ_WATCHDOG, vcpu) && 
+	    vcpu->arch.watchdog_enable) {
+		kvm_run->exit_reason = KVM_EXIT_WATCHDOG;
+		ret = 0;
+		goto out;
+	}
+
 	kvm_guest_enter();
 
 #ifdef CONFIG_PPC_FPU
@@ -978,6 +1096,12 @@  int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		}
 	}
 
+	if (kvm_check_request(KVM_REQ_WATCHDOG, vcpu) &&
+	    vcpu->arch.watchdog_enable) {
+		run->exit_reason = KVM_EXIT_WATCHDOG;
+		r = RESUME_HOST | (r & RESUME_FLAG_NV);
+	}
+
 	return r;
 }
 
@@ -1106,7 +1230,14 @@  static int set_sregs_base(struct kvm_vcpu *vcpu,
 	}
 
 	if (sregs->u.e.update_special & KVM_SREGS_E_UPDATE_TSR) {
+		u32 old_tsr = vcpu->arch.tsr;
+
 		vcpu->arch.tsr = sregs->u.e.tsr;
+
+		if ((old_tsr ^ vcpu->arch.tsr) &
+		    (TSR_ENW | TSR_WIS | TCR_WRC_MASK))
+			arm_next_watchdog(vcpu);
+
 		update_timer_ints(vcpu);
 	}
 
@@ -1267,6 +1398,7 @@  void kvmppc_core_commit_memory_region(struct kvm *kvm,
 void kvmppc_set_tcr(struct kvm_vcpu *vcpu, u32 new_tcr)
 {
 	vcpu->arch.tcr = new_tcr;
+	arm_next_watchdog(vcpu);
 	update_timer_ints(vcpu);
 }
 
@@ -1281,6 +1413,14 @@  void kvmppc_set_tsr_bits(struct kvm_vcpu *vcpu, u32 tsr_bits)
 void kvmppc_clr_tsr_bits(struct kvm_vcpu *vcpu, u32 tsr_bits)
 {
 	clear_bits(tsr_bits, &vcpu->arch.tsr);
+
+	/*
+	 * We may have stopped the watchdog due to
+	 * being stuck on final expiration.
+	 */
+	if (tsr_bits & (TSR_ENW | TSR_WIS | TCR_WRC_MASK))
+		arm_next_watchdog(vcpu);
+
 	update_timer_ints(vcpu);
 }
 
diff --git a/arch/powerpc/kvm/booke_emulate.c b/arch/powerpc/kvm/booke_emulate.c
index 12834bb..5a66ade 100644
--- a/arch/powerpc/kvm/booke_emulate.c
+++ b/arch/powerpc/kvm/booke_emulate.c
@@ -145,6 +145,14 @@  int kvmppc_booke_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
 		kvmppc_clr_tsr_bits(vcpu, spr_val);
 		break;
 	case SPRN_TCR:
+		/*
+		 * WRC is a 2-bit field that is supposed to preserve its
+		 * value once written to non-zero.
+		 */
+		if (vcpu->arch.tcr & TCR_WRC_MASK) {
+			spr_val &= ~TCR_WRC_MASK;
+			spr_val |= vcpu->arch.tcr & TCR_WRC_MASK;
+		}
 		kvmppc_set_tcr(vcpu, spr_val);
 		break;
 
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 87f4dc8..3c50b81 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -38,9 +38,11 @@ 
 
 int kvm_arch_vcpu_runnable(struct kvm_vcpu *v)
 {
-	return !(v->arch.shared->msr & MSR_WE) ||
-	       !!(v->arch.pending_exceptions) ||
-	       v->requests;
+	bool ret = !(v->arch.shared->msr & MSR_WE) ||
+		   !!(v->arch.pending_exceptions) ||
+		   v->requests;
+
+	return ret;
 }
 
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
@@ -237,6 +239,7 @@  int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_PPC_GET_PVINFO:
 #if defined(CONFIG_KVM_E500V2) || defined(CONFIG_KVM_E500MC)
 	case KVM_CAP_SW_TLB:
+	case KVM_CAP_PPC_WDT:
 #endif
 		r = 1;
 		break;
@@ -386,13 +389,23 @@  int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 #ifdef CONFIG_KVM_EXIT_TIMING
 	mutex_init(&vcpu->arch.exit_timing_lock);
 #endif
-
+#ifdef CONFIG_BOOKE
+	spin_lock_init(&vcpu->arch.wdt_lock);
+	/* setup watchdog timer once */
+	setup_timer(&vcpu->arch.wdt_timer, kvmppc_watchdog_func,
+		    (unsigned long)vcpu);
+#endif
 	return 0;
 }
 
 void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu)
 {
 	kvmppc_mmu_destroy(vcpu);
+#ifdef CONFIG_BOOKE
+	spin_lock(&vcpu->arch.wdt_lock);
+	del_timer(&vcpu->arch.wdt_timer);
+	spin_unlock(&vcpu->arch.wdt_lock);
+#endif
 }
 
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
@@ -637,6 +650,12 @@  static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
 		r = 0;
 		vcpu->arch.papr_enabled = true;
 		break;
+#ifdef CONFIG_BOOKE
+	case KVM_CAP_PPC_WDT:
+		r = 0;
+		vcpu->arch.watchdog_enable = true;
+		break;
+#endif
 #if defined(CONFIG_KVM_E500V2) || defined(CONFIG_KVM_E500MC)
 	case KVM_CAP_SW_TLB: {
 		struct kvm_config_tlb cfg;
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 2ce09aa..07dcab3 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -163,6 +163,7 @@  struct kvm_pit_config {
 #define KVM_EXIT_OSI              18
 #define KVM_EXIT_PAPR_HCALL	  19
 #define KVM_EXIT_S390_UCONTROL	  20
+#define KVM_EXIT_WATCHDOG         21
 
 /* For KVM_EXIT_INTERNAL_ERROR */
 #define KVM_INTERNAL_ERROR_EMULATION 1
@@ -618,6 +619,7 @@  struct kvm_ppc_smmu_info {
 #define KVM_CAP_PPC_GET_SMMU_INFO 78
 #define KVM_CAP_S390_COW 79
 #define KVM_CAP_PPC_ALLOC_HTAB 80
+#define KVM_CAP_PPC_WDT	81
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 27ac8a4..41d32be 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -69,6 +69,7 @@ 
 #define KVM_REQ_IMMEDIATE_EXIT    15
 #define KVM_REQ_PMU               16
 #define KVM_REQ_PMI               17
+#define KVM_REQ_WATCHDOG          18
 
 #define KVM_USERSPACE_IRQ_SOURCE_ID	0