Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b6958ce44a11a9e9425d2b67a653b1ca2a27796f
Commit:     b6958ce44a11a9e9425d2b67a653b1ca2a27796f
Parent:     1fd4f2a5ed8f80cf6e23d2bdf78554f6a1ac7997
Author:     Eddie Dong <[EMAIL PROTECTED]>
AuthorDate: Wed Jul 18 12:15:21 2007 +0300
Committer:  Avi Kivity <[EMAIL PROTECTED]>
CommitDate: Sat Oct 13 10:18:25 2007 +0200

    KVM: Emulate hlt in the kernel
    
    By sleeping in the kernel when hlt is executed, we simplify the in-kernel
    guest interrupt path considerably.
    
    Signed-off-by: Gregory Haskins <[EMAIL PROTECTED]>
    Signed-off-by: Yaozu (Eddie) Dong <[EMAIL PROTECTED]>
    Signed-off-by: Avi Kivity <[EMAIL PROTECTED]>
---
 drivers/kvm/i8259.c    |    3 +++
 drivers/kvm/irq.c      |    4 ++++
 drivers/kvm/kvm.h      |    2 ++
 drivers/kvm/kvm_main.c |   41 +++++++++++++++++++++++++++++++++++------
 drivers/kvm/svm.c      |    9 ++++++---
 drivers/kvm/vmx.c      |    8 ++++++--
 include/linux/kvm.h    |    1 +
 7 files changed, 57 insertions(+), 11 deletions(-)

diff --git a/drivers/kvm/i8259.c b/drivers/kvm/i8259.c
index 40ad104..ee6030d 100644
--- a/drivers/kvm/i8259.c
+++ b/drivers/kvm/i8259.c
@@ -413,8 +413,11 @@ static void picdev_read(struct kvm_io_device *this,
 static void pic_irq_request(void *opaque, int level)
 {
        struct kvm *kvm = opaque;
+       struct kvm_vcpu *vcpu = kvm->vcpus[0];
 
        pic_irqchip(kvm)->output = level;
+       if (vcpu)
+               kvm_vcpu_kick(vcpu);
 }
 
 struct kvm_pic *kvm_create_pic(struct kvm *kvm)
diff --git a/drivers/kvm/irq.c b/drivers/kvm/irq.c
index 5265f82..e09cd65 100644
--- a/drivers/kvm/irq.c
+++ b/drivers/kvm/irq.c
@@ -70,6 +70,10 @@ void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
 {
        int ipi_pcpu = vcpu->cpu;
 
+       if (waitqueue_active(&vcpu->wq)) {
+               wake_up_interruptible(&vcpu->wq);
+               ++vcpu->stat.halt_wakeup;
+       }
        if (vcpu->guest_mode)
                smp_call_function_single(ipi_pcpu, vcpu_kick_intr, vcpu, 0, 0);
 }
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 8d07a99..bb506b7 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -231,6 +231,7 @@ struct kvm_stat {
        u32 signal_exits;
        u32 irq_window_exits;
        u32 halt_exits;
+       u32 halt_wakeup;
        u32 request_irq_exits;
        u32 irq_exits;
        u32 light_exits;
@@ -353,6 +354,7 @@ struct kvm_vcpu {
        gva_t mmio_fault_cr2;
        struct kvm_pio_request pio;
        void *pio_data;
+       wait_queue_head_t wq;
 
        int sigset_active;
        sigset_t sigset;
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index ffbdadd..4384364 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -76,6 +76,7 @@ static struct kvm_stats_debugfs_item {
        { "signal_exits", STAT_OFFSET(signal_exits) },
        { "irq_window", STAT_OFFSET(irq_window_exits) },
        { "halt_exits", STAT_OFFSET(halt_exits) },
+       { "halt_wakeup", STAT_OFFSET(halt_wakeup) },
        { "request_irq", STAT_OFFSET(request_irq_exits) },
        { "irq_exits", STAT_OFFSET(irq_exits) },
        { "light_exits", STAT_OFFSET(light_exits) },
@@ -248,6 +249,7 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, 
unsigned id)
        vcpu->mmu.root_hpa = INVALID_PAGE;
        vcpu->kvm = kvm;
        vcpu->vcpu_id = id;
+       init_waitqueue_head(&vcpu->wq);
 
        page = alloc_page(GFP_KERNEL | __GFP_ZERO);
        if (!page) {
@@ -1307,15 +1309,41 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
 }
 EXPORT_SYMBOL_GPL(emulate_instruction);
 
-int kvm_emulate_halt(struct kvm_vcpu *vcpu)
+/*
+ * The vCPU has executed a HLT instruction with in-kernel mode enabled.
+ */
+static void kvm_vcpu_kernel_halt(struct kvm_vcpu *vcpu)
 {
-       if (vcpu->irq_summary ||
-               (irqchip_in_kernel(vcpu->kvm) && kvm_cpu_has_interrupt(vcpu)))
-               return 1;
+       DECLARE_WAITQUEUE(wait, current);
+
+       add_wait_queue(&vcpu->wq, &wait);
+
+       /*
+        * We will block until either an interrupt or a signal wakes us up
+        */
+       while(!(irqchip_in_kernel(vcpu->kvm) && kvm_cpu_has_interrupt(vcpu))
+             && !vcpu->irq_summary
+             && !signal_pending(current)) {
+               set_current_state(TASK_INTERRUPTIBLE);
+               vcpu_put(vcpu);
+               schedule();
+               vcpu_load(vcpu);
+       }
 
-       vcpu->run->exit_reason = KVM_EXIT_HLT;
+       remove_wait_queue(&vcpu->wq, &wait);
+       set_current_state(TASK_RUNNING);
+}
+
+int kvm_emulate_halt(struct kvm_vcpu *vcpu)
+{
        ++vcpu->stat.halt_exits;
-       return 0;
+       if (irqchip_in_kernel(vcpu->kvm)) {
+               kvm_vcpu_kernel_halt(vcpu);
+               return 1;
+       } else {
+               vcpu->run->exit_reason = KVM_EXIT_HLT;
+               return 0;
+       }
 }
 EXPORT_SYMBOL_GPL(kvm_emulate_halt);
 
@@ -2916,6 +2944,7 @@ static long kvm_dev_ioctl(struct file *filp,
 
                switch (ext) {
                case KVM_CAP_IRQCHIP:
+               case KVM_CAP_HLT:
                        r = 1;
                        break;
                default:
diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index d576451..a347b61 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -1398,9 +1398,12 @@ static void do_interrupt_requests(struct vcpu_svm *svm,
 static void post_kvm_run_save(struct vcpu_svm *svm,
                              struct kvm_run *kvm_run)
 {
-       kvm_run->ready_for_interrupt_injection
-               = (svm->vcpu.interrupt_window_open &&
-                  svm->vcpu.irq_summary == 0);
+       if (irqchip_in_kernel(svm->vcpu.kvm))
+               kvm_run->ready_for_interrupt_injection = 1;
+       else
+               kvm_run->ready_for_interrupt_injection =
+                                        (svm->vcpu.interrupt_window_open &&
+                                         svm->vcpu.irq_summary == 0);
        kvm_run->if_flag = (svm->vmcb->save.rflags & X86_EFLAGS_IF) != 0;
        kvm_run->cr8 = get_cr8(&svm->vcpu);
        kvm_run->apic_base = kvm_get_apic_base(&svm->vcpu);
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index c4cc17c..7ec8cf8 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1961,8 +1961,12 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu,
        kvm_run->if_flag = (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) != 0;
        kvm_run->cr8 = get_cr8(vcpu);
        kvm_run->apic_base = kvm_get_apic_base(vcpu);
-       kvm_run->ready_for_interrupt_injection = (vcpu->interrupt_window_open &&
-                                                 vcpu->irq_summary == 0);
+       if (irqchip_in_kernel(vcpu->kvm))
+               kvm_run->ready_for_interrupt_injection = 1;
+       else
+               kvm_run->ready_for_interrupt_injection =
+                                       (vcpu->interrupt_window_open &&
+                                        vcpu->irq_summary == 0);
 }
 
 static int handle_interrupt_window(struct kvm_vcpu *vcpu,
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 997bb3e..b0a13d1 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -283,6 +283,7 @@ struct kvm_signal_mask {
  * Extension capability list.
  */
 #define KVM_CAP_IRQCHIP          0
+#define KVM_CAP_HLT      1
 
 /*
  * ioctls for VM fds
-
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