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[PATCH 2/2] KVM: PPC: booke: Add watchdog emulation

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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: Liu Yu <yu.liu@xxxxxxxxxxxxx>
Signed-off-by: Scott Wood <scottwood@xxxxxxxxxxxxx>
Signed-off-by: Bharat Bhushan <bharat.bhushan@xxxxxxxxxxxxx>
---
 arch/powerpc/include/asm/kvm_host.h  |    2 +
 arch/powerpc/include/asm/kvm_ppc.h   |    3 +
 arch/powerpc/include/asm/reg_booke.h |    2 +
 arch/powerpc/kvm/44x.c               |    1 +
 arch/powerpc/kvm/booke.c             |  125 ++++++++++++++++++++++++++++++++++
 arch/powerpc/kvm/booke_emulate.c     |    6 ++-
 arch/powerpc/kvm/powerpc.c           |   25 ++++++-
 include/linux/kvm.h                  |    2 +
 8 files changed, 162 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 50ea12f..a9e5aed 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -467,6 +467,7 @@ struct kvm_vcpu_arch {
 	ulong fault_esr;
 	ulong queued_dear;
 	ulong queued_esr;
+	struct timer_list wdt_timer;
 	u32 tlbcfg[4];
 	u32 mmucfg;
 	u32 epr;
@@ -482,6 +483,7 @@ 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..7efb3f5 100644
--- a/arch/powerpc/include/asm/reg_booke.h
+++ b/arch/powerpc/include/asm/reg_booke.h
@@ -538,6 +538,8 @@
 #define FP_2_21		3		/* 2^21 clocks */
 #define TCR_FIE		0x00800000	/* FIT Interrupt Enable */
 #define TCR_ARE		0x00400000	/* Auto Reload Enable */
+#define TCR_GET_FSL_WP(tcr)  ((((tcr) & 0xC0000000) >> 30) | \
+			      (((tcr) & 0x1E0000) >> 15))
 
 /* Bit definitions for the TSR. */
 #define TSR_ENW		0x80000000	/* Enable Next Watchdog */
diff --git a/arch/powerpc/kvm/44x.c b/arch/powerpc/kvm/44x.c
index 50e7dbc..a213aba 100644
--- a/arch/powerpc/kvm/44x.c
+++ b/arch/powerpc/kvm/44x.c
@@ -28,6 +28,7 @@
 #include <asm/kvm_44x.h>
 #include <asm/kvm_ppc.h>
 
+#include "booke.h"
 #include "44x_tlb.h"
 #include "booke.h"
 
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index d25a097..ad30f75 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 +415,98 @@ static int kvmppc_booke_irqprio_deliver(struct kvm_vcpu *vcpu,
 	return allowed;
 }
 
+/*
+ * The timer system can almost deal with LONG_MAX timeouts, except that
+ * when you get very close to LONG_MAX, the slack added can cause overflow.
+ *
+ * LONG_MAX/2 is a conservative threshold, but it should be adequate for
+ * any realistic use.
+ */
+#define MAX_TIMEOUT (LONG_MAX/2)
+
+/*
+ * Return the number of jiffies until the next timeout.  If the timeout is
+ * longer than the MAX_TIMEOUT, that we return MAX_TIMEOUT instead.
+ */
+static unsigned long watchdog_next_timeout(struct kvm_vcpu *vcpu)
+{
+	unsigned long long tb, mask, nr_jiffies = 0;
+	u32 period = TCR_GET_FSL_WP(vcpu->arch.tcr);
+
+	mask = 1ULL << (63 - period);
+	tb = get_tb();
+	if (tb & mask)
+		nr_jiffies += mask;
+
+	nr_jiffies += mask - (tb & (mask - 1));
+
+	if (do_div(nr_jiffies, tb_ticks_per_jiffy))
+		nr_jiffies++;
+
+	return min_t(unsigned long long, nr_jiffies, MAX_TIMEOUT);
+}
+
+static void arm_next_watchdog(struct kvm_vcpu *vcpu)
+{
+	unsigned long nr_jiffies;
+
+	nr_jiffies = watchdog_next_timeout(vcpu);
+	if (nr_jiffies < MAX_TIMEOUT)
+		mod_timer(&vcpu->arch.wdt_timer, jiffies + nr_jiffies);
+	else
+		del_timer(&vcpu->arch.wdt_timer);
+}
+
+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) {
+				new_tsr = (tsr & ~TCR_WRC_MASK) |
+					  (vcpu->arch.tcr & TCR_WRC_MASK);
+				vcpu->arch.tcr &= ~TCR_WRC_MASK;
+				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 | TCR_WRC_MASK)) {
+		smp_wmb();
+		kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu);
+		kvm_vcpu_kick(vcpu);
+	}
+
+	/*
+	 * Avoid getting a storm of timers if the guest sets
+	 * the period very short.  We'll restart it if anything
+	 * changes.
+	 */
+	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 +613,12 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 		goto out;
 	}
 
+	if (vcpu->arch.tsr & TCR_WRC_MASK) {
+		kvm_run->exit_reason = KVM_EXIT_WDT;
+		ret = 0;
+		goto out;
+	}
+
 	kvm_guest_enter();
 
 #ifdef CONFIG_PPC_FPU
@@ -977,6 +1080,10 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			kvmppc_account_exit(vcpu, SIGNAL_EXITS);
 		}
 	}
+	if (vcpu->arch.tsr & TCR_WRC_MASK) {
+		run->exit_reason = KVM_EXIT_WDT;
+		r = RESUME_HOST | (r & RESUME_FLAG_NV);
+	}
 
 	return r;
 }
@@ -1106,7 +1213,14 @@ 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 +1381,8 @@ 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;
+	if (vcpu->arch.watchdog_enable)
+		arm_next_watchdog(vcpu);
 	update_timer_ints(vcpu);
 }
 
@@ -1281,6 +1397,15 @@ 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 (vcpu->arch.watchdog_enable && (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..cc94d42 100644
--- a/arch/powerpc/kvm/booke_emulate.c
+++ b/arch/powerpc/kvm/booke_emulate.c
@@ -145,7 +145,11 @@ 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:
-		kvmppc_set_tcr(vcpu, spr_val);
+		/* WRC can only be programmed when WRC=0 */
+		if (TCR_WRC_MASK & vcpu->arch.tcr)
+			spr_val &= ~TCR_WRC_MASK;
+		kvmppc_set_tcr(vcpu,
+		               spr_val | (TCR_WRC_MASK & vcpu->arch.tcr));
 		break;
 
 	case SPRN_DECAR:
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 87f4dc8..35a1ff3 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -38,9 +38,15 @@
 
 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;
+
+#ifdef CONFIG_BOOKE
+	ret = ret || (v->arch.tsr & TCR_WRC_MASK);
+#endif
+
+	return ret;
 }
 
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
@@ -237,6 +243,7 @@ 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;
@@ -393,6 +400,10 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu)
 {
 	kvmppc_mmu_destroy(vcpu);
+#ifdef CONFIG_BOOKE
+	if (vcpu->arch.watchdog_enable)
+		del_timer(&vcpu->arch.wdt_timer);
+#endif
 }
 
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
@@ -637,6 +648,14 @@ 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;
+		setup_timer(&vcpu->arch.wdt_timer, kvmppc_watchdog_func,
+		            (unsigned long)vcpu);
+		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..b9fdb52 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_WDT              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
 
-- 
1.7.0.4


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