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authorFeng Wu <feng.wu@intel.com>2015-09-18 22:29:55 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2015-10-01 15:06:53 +0200
commitbf9f6ac8d74969690df1485b33b7c238ca9f2269 (patch)
treecfaa21f2831d959dca9bdb4c4ad9e329fec4d5e8
parent28b835d60fcc2498e717cf5e6f0c3691c24546f7 (diff)
downloadlwn-bf9f6ac8d74969690df1485b33b7c238ca9f2269.tar.gz
lwn-bf9f6ac8d74969690df1485b33b7c238ca9f2269.zip
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 - Set 'NV' to POSTED_INTR_WAKEUP_VECTOR post-block: - Remove the vCPU from the per-CPU list Signed-off-by: Feng Wu <feng.wu@intel.com> [Concentrate invocation of pre/post-block hooks to vcpu_block. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--Documentation/virtual/kvm/locking.txt12
-rw-r--r--arch/x86/include/asm/kvm_host.h11
-rw-r--r--arch/x86/kvm/vmx.c153
-rw-r--r--arch/x86/kvm/x86.c34
-rw-r--r--include/linux/kvm_host.h3
-rw-r--r--virt/kvm/kvm_main.c3
6 files changed, 206 insertions, 10 deletions
diff --git a/Documentation/virtual/kvm/locking.txt b/Documentation/virtual/kvm/locking.txt
index d68af4dc3006..19f94a6b9bb0 100644
--- a/Documentation/virtual/kvm/locking.txt
+++ b/Documentation/virtual/kvm/locking.txt
@@ -166,3 +166,15 @@ Comment: The srcu read lock must be held while accessing memslots (e.g.
MMIO/PIO address->device structure mapping (kvm->buses).
The srcu index can be stored in kvm_vcpu->srcu_idx per vcpu
if it is needed by multiple functions.
+
+Name: blocked_vcpu_on_cpu_lock
+Type: spinlock_t
+Arch: x86
+Protects: blocked_vcpu_on_cpu
+Comment: This is a per-CPU lock and it is used for VT-d posted-interrupts.
+ When VT-d posted-interrupts is supported and the VM has assigned
+ devices, we put the blocked vCPU on the list blocked_vcpu_on_cpu
+ protected by blocked_vcpu_on_cpu_lock, when VT-d hardware issues
+ wakeup notification event since external interrupts from the
+ assigned devices happens, we will find the vCPU on the list to
+ wakeup.
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 15664994b6f3..cdbdb559ecd2 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -899,6 +899,17 @@ struct kvm_x86_ops {
/* pmu operations of sub-arch */
const struct kvm_pmu_ops *pmu_ops;
+ /*
+ * Architecture specific hooks for vCPU blocking due to
+ * HLT instruction.
+ * Returns for .pre_block():
+ * - 0 means continue to block the vCPU.
+ * - 1 means we cannot block the vCPU since some event
+ * happens during this period, such as, 'ON' bit in
+ * posted-interrupts descriptor is set.
+ */
+ int (*pre_block)(struct kvm_vcpu *vcpu);
+ void (*post_block)(struct kvm_vcpu *vcpu);
int (*update_pi_irte)(struct kvm *kvm, unsigned int host_irq,
uint32_t guest_irq, bool set);
};
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 99f5c61954ea..c5c22831aee2 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -878,6 +878,13 @@ 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;
@@ -2986,6 +2993,8 @@ 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
@@ -6045,6 +6054,25 @@ static void update_ple_window_actual_max(void)
ple_window_grow, INT_MIN);
}
+/*
+ * Handler for POSTED_INTERRUPT_WAKEUP_VECTOR.
+ */
+static 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 __init int hardware_setup(void)
{
int r = -ENOMEM, i, msr;
@@ -6231,6 +6259,8 @@ static __init int hardware_setup(void)
kvm_x86_ops->enable_log_dirty_pt_masked = NULL;
}
+ kvm_set_posted_intr_wakeup_handler(wakeup_handler);
+
return alloc_kvm_area();
out8:
@@ -10432,6 +10462,126 @@ static void vmx_enable_log_dirty_pt_masked(struct kvm *kvm,
}
/*
+ * This routine does the following things for vCPU which is going
+ * to be blocked if VT-d PI is enabled.
+ * - Store the vCPU to the wakeup list, so when interrupts happen
+ * we can find the right vCPU to wake up.
+ * - Change the Posted-interrupt descriptor as below:
+ * 'NDST' <-- vcpu->pre_pcpu
+ * 'NV' <-- POSTED_INTR_WAKEUP_VECTOR
+ * - If 'ON' is set during this process, which means at least one
+ * interrupt is posted for this vCPU, we cannot block it, in
+ * this case, return 1, otherwise, return 0.
+ *
+ */
+static int vmx_pre_block(struct kvm_vcpu *vcpu)
+{
+ unsigned long flags;
+ unsigned int dest;
+ struct pi_desc old, new;
+ struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
+
+ if (!kvm_arch_has_assigned_device(vcpu->kvm) ||
+ !irq_remapping_cap(IRQ_POSTING_CAP))
+ return 0;
+
+ vcpu->pre_pcpu = vcpu->cpu;
+ spin_lock_irqsave(&per_cpu(blocked_vcpu_on_cpu_lock,
+ vcpu->pre_pcpu), flags);
+ list_add_tail(&vcpu->blocked_vcpu_list,
+ &per_cpu(blocked_vcpu_on_cpu,
+ vcpu->pre_pcpu));
+ spin_unlock_irqrestore(&per_cpu(blocked_vcpu_on_cpu_lock,
+ vcpu->pre_pcpu), 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) {
+ spin_lock_irqsave(&per_cpu(blocked_vcpu_on_cpu_lock,
+ vcpu->pre_pcpu), flags);
+ list_del(&vcpu->blocked_vcpu_list);
+ spin_unlock_irqrestore(
+ &per_cpu(blocked_vcpu_on_cpu_lock,
+ vcpu->pre_pcpu), flags);
+ vcpu->pre_pcpu = -1;
+
+ return 1;
+ }
+
+ WARN((pi_desc->sn == 1),
+ "Warning: SN field of posted-interrupts "
+ "is set before blocking\n");
+
+ /*
+ * Since vCPU can be preempted during this process,
+ * vcpu->cpu could be different with pre_pcpu, we
+ * need to set pre_pcpu as the destination of wakeup
+ * notification event, then we can find the right vCPU
+ * to wakeup in wakeup handler if interrupts happen
+ * when the vCPU is in blocked state.
+ */
+ dest = cpu_physical_id(vcpu->pre_pcpu);
+
+ if (x2apic_enabled())
+ new.ndst = dest;
+ else
+ new.ndst = (dest << 8) & 0xFF00;
+
+ /* set 'NV' to 'wakeup vector' */
+ new.nv = POSTED_INTR_WAKEUP_VECTOR;
+ } while (cmpxchg(&pi_desc->control, old.control,
+ new.control) != old.control);
+
+ return 0;
+}
+
+static void vmx_post_block(struct kvm_vcpu *vcpu)
+{
+ struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
+ struct pi_desc old, new;
+ unsigned int dest;
+ unsigned long flags;
+
+ if (!kvm_arch_has_assigned_device(vcpu->kvm) ||
+ !irq_remapping_cap(IRQ_POSTING_CAP))
+ return;
+
+ do {
+ old.control = new.control = pi_desc->control;
+
+ dest = cpu_physical_id(vcpu->cpu);
+
+ if (x2apic_enabled())
+ new.ndst = dest;
+ else
+ new.ndst = (dest << 8) & 0xFF00;
+
+ /* Allow posting non-urgent interrupts */
+ new.sn = 0;
+
+ /* set 'NV' to 'notification vector' */
+ new.nv = POSTED_INTR_VECTOR;
+ } while (cmpxchg(&pi_desc->control, old.control,
+ new.control) != old.control);
+
+ if(vcpu->pre_pcpu != -1) {
+ spin_lock_irqsave(
+ &per_cpu(blocked_vcpu_on_cpu_lock,
+ vcpu->pre_pcpu), flags);
+ list_del(&vcpu->blocked_vcpu_list);
+ spin_unlock_irqrestore(
+ &per_cpu(blocked_vcpu_on_cpu_lock,
+ vcpu->pre_pcpu), flags);
+ vcpu->pre_pcpu = -1;
+ }
+}
+
+/*
* vmx_update_pi_irte - set IRTE for Posted-Interrupts
*
* @kvm: kvm
@@ -10622,6 +10772,9 @@ static struct kvm_x86_ops vmx_x86_ops = {
.flush_log_dirty = vmx_flush_log_dirty,
.enable_log_dirty_pt_masked = vmx_enable_log_dirty_pt_masked,
+ .pre_block = vmx_pre_block,
+ .post_block = vmx_post_block,
+
.pmu_ops = &intel_pmu_ops,
.update_pi_irte = vmx_update_pi_irte,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b8425a769c0a..2d2c9bb0d6d6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6335,6 +6335,20 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
}
}
+ /*
+ * KVM_REQ_EVENT is not set when posted interrupts are set by
+ * VT-d hardware, so we have to update RVI unconditionally.
+ */
+ 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) {
@@ -6351,13 +6365,6 @@ 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);
}
@@ -6493,10 +6500,15 @@ out:
static inline int vcpu_block(struct kvm *kvm, struct kvm_vcpu *vcpu)
{
- if (!kvm_arch_vcpu_runnable(vcpu)) {
+ if (!kvm_arch_vcpu_runnable(vcpu) &&
+ (!kvm_x86_ops->pre_block || kvm_x86_ops->pre_block(vcpu) == 0)) {
srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
kvm_vcpu_block(vcpu);
vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
+
+ if (kvm_x86_ops->post_block)
+ kvm_x86_ops->post_block(vcpu);
+
if (!kvm_check_request(KVM_REQ_UNHALT, vcpu))
return 1;
}
@@ -6528,10 +6540,12 @@ static int vcpu_run(struct kvm_vcpu *vcpu)
for (;;) {
if (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE &&
- !vcpu->arch.apf.halted)
+ !vcpu->arch.apf.halted) {
r = vcpu_enter_guest(vcpu);
- else
+ } else {
r = vcpu_block(kvm, vcpu);
+ }
+
if (r <= 0)
break;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 5c3f4538807f..9596a2f0977b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -234,6 +234,9 @@ struct kvm_vcpu {
unsigned long requests;
unsigned long guest_debug;
+ int pre_pcpu;
+ struct list_head blocked_vcpu_list;
+
struct mutex mutex;
struct kvm_run *run;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index afd7ae6aec65..a75502c93c3e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -230,6 +230,9 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
init_waitqueue_head(&vcpu->wq);
kvm_async_pf_vcpu_init(vcpu);
+ vcpu->pre_pcpu = -1;
+ INIT_LIST_HEAD(&vcpu->blocked_vcpu_list);
+
page = alloc_page(GFP_KERNEL | __GFP_ZERO);
if (!page) {
r = -ENOMEM;