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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>
This commit is contained in:
Feng Wu 2015-09-18 22:29:55 +08:00 committed by Paolo Bonzini
parent 28b835d60f
commit bf9f6ac8d7
6 changed files with 206 additions and 10 deletions
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12
Documentation/virtual/kvm/locking.txt
View File

@ -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.

11
arch/x86/include/asm/kvm_host.h
View File

@ -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);
};

153
arch/x86/kvm/vmx.c
View File

@ -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:
@ -10431,6 +10461,126 @@ static void vmx_enable_log_dirty_pt_masked(struct kvm *kvm,
kvm_mmu_clear_dirty_pt_masked(kvm, memslot, offset, mask);
}
/*
* 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
*
@ -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,

34
arch/x86/kvm/x86.c
View File

@ -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;

3
include/linux/kvm_host.h
View File

@ -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;

3
virt/kvm/kvm_main.c
View File

@ -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;