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Date: Fri, 12 Dec 2014 23:14:58 +0800
From: Feng Wu <feng.wu@...el.com>
To: tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
x86@...nel.org, gleb@...nel.org, pbonzini@...hat.com,
dwmw2@...radead.org, joro@...tes.org, alex.williamson@...hat.com,
jiang.liu@...ux.intel.com
Cc: eric.auger@...aro.org, linux-kernel@...r.kernel.org,
iommu@...ts.linux-foundation.org, kvm@...r.kernel.org,
Feng Wu <feng.wu@...el.com>
Subject: [v3 24/26] KVM: Update Posted-Interrupts Descriptor when vCPU is blocked
This patch updates the Posted-Interrupts Descriptor when vCPU
is blocked.
pre-block:
- Add the vCPU to the blocked per-CPU list
- Clear 'SN'
- Set 'NV' to POSTED_INTR_WAKEUP_VECTOR
post-block:
- Remove the vCPU from the per-CPU list
Signed-off-by: Feng Wu <feng.wu@...el.com>
---
arch/x86/include/asm/kvm_host.h | 2 +
arch/x86/kvm/vmx.c | 96 +++++++++++++++++++++++++++++++++++++++++
arch/x86/kvm/x86.c | 22 +++++++---
include/linux/kvm_host.h | 4 ++
virt/kvm/kvm_main.c | 6 +++
5 files changed, 123 insertions(+), 7 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 13e3e40..32c110a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -101,6 +101,8 @@ static inline gfn_t gfn_to_index(gfn_t gfn, gfn_t base_gfn, int level)
#define ASYNC_PF_PER_VCPU 64
+extern void (*wakeup_handler_callback)(void);
+
enum kvm_reg {
VCPU_REGS_RAX = 0,
VCPU_REGS_RCX = 1,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index bf2e6cd..a1c83a2 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -832,6 +832,13 @@ static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
static DEFINE_PER_CPU(struct list_head, loaded_vmcss_on_cpu);
static DEFINE_PER_CPU(struct desc_ptr, host_gdt);
+/*
+ * We maintian a per-CPU linked-list of vCPU, so in wakeup_handler() we
+ * can find which vCPU should be waken up.
+ */
+static DEFINE_PER_CPU(struct list_head, blocked_vcpu_on_cpu);
+static DEFINE_PER_CPU(spinlock_t, blocked_vcpu_on_cpu_lock);
+
static unsigned long *vmx_io_bitmap_a;
static unsigned long *vmx_io_bitmap_b;
static unsigned long *vmx_msr_bitmap_legacy;
@@ -1921,6 +1928,7 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
struct pi_desc old, new;
unsigned int dest;
+ unsigned long flags;
memset(&old, 0, sizeof(old));
memset(&new, 0, sizeof(new));
@@ -1942,6 +1950,20 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
new.nv = POSTED_INTR_VECTOR;
} while (cmpxchg(&pi_desc->control, old.control,
new.control) != old.control);
+
+ /*
+ * Delete the vCPU from the related wakeup queue
+ * if we are resuming from blocked state
+ */
+ if (vcpu->blocked) {
+ vcpu->blocked = false;
+ spin_lock_irqsave(&per_cpu(blocked_vcpu_on_cpu_lock,
+ vcpu->wakeup_cpu), flags);
+ list_del(&vcpu->blocked_vcpu_list);
+ spin_unlock_irqrestore(&per_cpu(blocked_vcpu_on_cpu_lock,
+ vcpu->wakeup_cpu), flags);
+ vcpu->wakeup_cpu = -1;
+ }
}
}
@@ -1950,6 +1972,9 @@ static void vmx_vcpu_put(struct kvm_vcpu *vcpu)
if (irq_remapping_cap(IRQ_POSTING_CAP)) {
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
struct pi_desc old, new;
+ unsigned long flags;
+ int cpu;
+ struct cpumask cpu_others_mask;
memset(&old, 0, sizeof(old));
memset(&new, 0, sizeof(new));
@@ -1961,6 +1986,54 @@ static void vmx_vcpu_put(struct kvm_vcpu *vcpu)
pi_set_sn(&new);
} while (cmpxchg(&pi_desc->control, old.control,
new.control) != old.control);
+ } else if (vcpu->blocked) {
+ /*
+ * The vcpu is blocked on the wait queue.
+ * Store the blocked vCPU on the list of the
+ * vcpu->wakeup_cpu, which is the destination
+ * of the wake-up notification event.
+ */
+ vcpu->wakeup_cpu = vcpu->cpu;
+ spin_lock_irqsave(&per_cpu(blocked_vcpu_on_cpu_lock,
+ vcpu->wakeup_cpu), flags);
+ list_add_tail(&vcpu->blocked_vcpu_list,
+ &per_cpu(blocked_vcpu_on_cpu,
+ vcpu->wakeup_cpu));
+ spin_unlock_irqrestore(
+ &per_cpu(blocked_vcpu_on_cpu_lock,
+ vcpu->wakeup_cpu), flags);
+
+ do {
+ old.control = new.control = pi_desc->control;
+
+ /*
+ * We should not block the vCPU if
+ * an interrupt is posted for it.
+ */
+ if (pi_test_on(pi_desc) == 1) {
+ /*
+ * We need schedule the wakeup worker
+ * on a different cpu other than
+ * vcpu->cpu, because in some case,
+ * schedule_work() will call
+ * try_to_wake_up() which needs acquire
+ * the rq lock. This can cause deadlock.
+ */
+ cpumask_copy(&cpu_others_mask,
+ cpu_online_mask);
+ cpu_clear(vcpu->cpu, cpu_others_mask);
+ cpu = any_online_cpu(cpu_others_mask);
+
+ schedule_work_on(cpu,
+ &vcpu->wakeup_worker);
+ }
+
+ pi_clear_sn(&new);
+
+ /* set 'NV' to 'wakeup vector' */
+ new.nv = POSTED_INTR_WAKEUP_VECTOR;
+ } while (cmpxchg(&pi_desc->control, old.control,
+ new.control) != old.control);
}
}
@@ -2842,6 +2915,8 @@ static int hardware_enable(void)
return -EBUSY;
INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu));
+ INIT_LIST_HEAD(&per_cpu(blocked_vcpu_on_cpu, cpu));
+ spin_lock_init(&per_cpu(blocked_vcpu_on_cpu_lock, cpu));
/*
* Now we can enable the vmclear operation in kdump
@@ -9315,6 +9390,25 @@ static struct kvm_x86_ops vmx_x86_ops = {
.pi_set_sn = vmx_pi_set_sn,
};
+/*
+ * Handler for POSTED_INTERRUPT_WAKEUP_VECTOR.
+ */
+void wakeup_handler(void)
+{
+ struct kvm_vcpu *vcpu;
+ int cpu = smp_processor_id();
+
+ spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, cpu));
+ list_for_each_entry(vcpu, &per_cpu(blocked_vcpu_on_cpu, cpu),
+ blocked_vcpu_list) {
+ struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
+
+ if (pi_test_on(pi_desc) == 1)
+ kvm_vcpu_kick(vcpu);
+ }
+ spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, cpu));
+}
+
static int __init vmx_init(void)
{
int r, i, msr;
@@ -9429,6 +9523,8 @@ static int __init vmx_init(void)
update_ple_window_actual_max();
+ wakeup_handler_callback = wakeup_handler;
+
return 0;
out7:
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0033df3..1551a46 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6152,6 +6152,21 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
kvm_vcpu_reload_apic_access_page(vcpu);
}
+ /*
+ * Since posted-interrupts can be set by VT-d HW now, in this
+ * case, KVM_REQ_EVENT is not set. We move the following
+ * operations out of the if statement.
+ */
+ if (kvm_lapic_enabled(vcpu)) {
+ /*
+ * Update architecture specific hints for APIC
+ * virtual interrupt delivery.
+ */
+ if (kvm_x86_ops->hwapic_irr_update)
+ kvm_x86_ops->hwapic_irr_update(vcpu,
+ kvm_lapic_find_highest_irr(vcpu));
+ }
+
if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) {
kvm_apic_accept_events(vcpu);
if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
@@ -6168,13 +6183,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
kvm_x86_ops->enable_irq_window(vcpu);
if (kvm_lapic_enabled(vcpu)) {
- /*
- * Update architecture specific hints for APIC
- * virtual interrupt delivery.
- */
- if (kvm_x86_ops->hwapic_irr_update)
- kvm_x86_ops->hwapic_irr_update(vcpu,
- kvm_lapic_find_highest_irr(vcpu));
update_cr8_intercept(vcpu);
kvm_lapic_sync_to_vapic(vcpu);
}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 3d7242c..d981d16 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -239,6 +239,9 @@ struct kvm_vcpu {
unsigned long requests;
unsigned long guest_debug;
+ int wakeup_cpu;
+ struct list_head blocked_vcpu_list;
+
struct mutex mutex;
struct kvm_run *run;
@@ -282,6 +285,7 @@ struct kvm_vcpu {
} spin_loop;
#endif
bool preempted;
+ bool blocked;
struct kvm_vcpu_arch arch;
};
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ba53fd6..6deb994 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -233,6 +233,9 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
INIT_WORK(&vcpu->wakeup_worker, wakeup_thread);
+ vcpu->wakeup_cpu = -1;
+ INIT_LIST_HEAD(&vcpu->blocked_vcpu_list);
+
page = alloc_page(GFP_KERNEL | __GFP_ZERO);
if (!page) {
r = -ENOMEM;
@@ -243,6 +246,7 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
kvm_vcpu_set_in_spin_loop(vcpu, false);
kvm_vcpu_set_dy_eligible(vcpu, false);
vcpu->preempted = false;
+ vcpu->blocked = false;
r = kvm_arch_vcpu_init(vcpu);
if (r < 0)
@@ -1752,6 +1756,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
DEFINE_WAIT(wait);
for (;;) {
+ vcpu->blocked = true;
prepare_to_wait(&vcpu->wq, &wait, TASK_INTERRUPTIBLE);
if (kvm_arch_vcpu_runnable(vcpu)) {
@@ -1767,6 +1772,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
}
finish_wait(&vcpu->wq, &wait);
+ vcpu->blocked = false;
}
EXPORT_SYMBOL_GPL(kvm_vcpu_block);
--
1.9.1
--
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