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>
[bharat.bhushan@xxxxxxxxxxxxx: reworked patch]
---
v5:
- Checking that TSR_ENW/TSR_WIS are still set on KVM_EXIT_WATCHDOG.
- Moved watchdog_next_timeout() in lock.
v4:
- in v3 i forgot to add Scott Wood and Liu Yu signoff
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 | 19 +++++-
include/linux/kvm.h | 2 +
include/linux/kvm_host.h | 1 +
8 files changed, 182 insertions(+), 1 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 50ea12f..43cac48 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_enabled;
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..71b4ce9 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 +415,113 @@ 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;
+
+ spin_lock(&vcpu->arch.wdt_lock);
+ nr_jiffies = watchdog_next_timeout(vcpu);
+ /*
+ * 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) &&
+ vcpu->arch.watchdog_enabled) {
+ 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 +628,13 @@ 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.tsr & (TSR_ENW | TSR_WIS))) {
+ kvm_run->exit_reason = KVM_EXIT_WATCHDOG;
+ ret = 0;
+ goto out;
+ }
+
kvm_guest_enter();
#ifdef CONFIG_PPC_FPU
@@ -978,6 +1097,12 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
}
}
+ if (kvm_check_request(KVM_REQ_WATCHDOG, vcpu) &&
+ (vcpu->arch.tsr & (TSR_ENW | TSR_WIS))) {
+ run->exit_reason = KVM_EXIT_WATCHDOG;
+ r = RESUME_HOST | (r & RESUME_FLAG_NV);
+ }
+
return r;
}
@@ -1106,7 +1231,13 @@ 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))
+ 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))
+ 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..63457cb 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -220,6 +220,7 @@ int kvm_dev_ioctl_check_extension(long ext)
switch (ext) {
#ifdef CONFIG_BOOKE
case KVM_CAP_PPC_BOOKE_SREGS:
+ case KVM_CAP_PPC_BOOKE_WATCHDOG:
#else
case KVM_CAP_PPC_SEGSTATE:
case KVM_CAP_PPC_HIOR:
@@ -386,13 +387,23 @@ 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 +648,12 @@ 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_BOOKE_WATCHDOG:
+ r = 0;
+ vcpu->arch.watchdog_enabled = 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..9ff5aa5 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_BOOKE_WATCHDOG 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
--
1.7.0.4
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