[PATCH v6 2/5] KVM: VMX: Register a new IPI for posted interrupt

[Yang Zhang <yang.z.zhang@intel.com>]

From: Yang Zhang <yang.z.zhang@Intel.com>

Posted Interrupt feature requires a special IPI to deliver posted interrupt
to guest. And it should has a high priority so the interrupt will not be
blocked by others.
Normally, the posted interrupt will be consumed by vcpu if target vcpu is
running and transparent to OS. But in some cases, the interrupt will arrive
when target vcpu is scheduled out. And host will see it. So we need to
register a dump handler to handle it.

Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
---
 arch/x86/include/asm/entry_arch.h  |    4 ++++
 arch/x86/include/asm/hardirq.h     |    3 +++
 arch/x86/include/asm/hw_irq.h      |    1 +
 arch/x86/include/asm/irq_vectors.h |    5 +++++
 arch/x86/kernel/entry_64.S         |    5 +++++
 arch/x86/kernel/irq.c              |   22 ++++++++++++++++++++++
 arch/x86/kernel/irqinit.c          |    4 ++++
 7 files changed, 44 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/entry_arch.h b/arch/x86/include/asm/entry_arch.h
index 40afa00..9bd4eca 100644
--- a/arch/x86/include/asm/entry_arch.h
+++ b/arch/x86/include/asm/entry_arch.h
@@ -19,6 +19,10 @@ BUILD_INTERRUPT(reboot_interrupt,REBOOT_VECTOR)
 
 BUILD_INTERRUPT(x86_platform_ipi, X86_PLATFORM_IPI_VECTOR)
 
+#ifdef CONFIG_HAVE_KVM
+BUILD_INTERRUPT(kvm_posted_intr_ipi, POSTED_INTR_VECTOR)
+#endif
+
 /*
  * every pentium local APIC has two 'local interrupts', with a
  * soft-definable vector attached to both interrupts, one of
diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h
index 81f04ce..ab0ae1a 100644
--- a/arch/x86/include/asm/hardirq.h
+++ b/arch/x86/include/asm/hardirq.h
@@ -12,6 +12,9 @@ typedef struct {
 	unsigned int irq_spurious_count;
 	unsigned int icr_read_retry_count;
 #endif
+#ifdef CONFIG_HAVE_KVM
+	unsigned int kvm_posted_intr_ipis;
+#endif
 	unsigned int x86_platform_ipis;	/* arch dependent */
 	unsigned int apic_perf_irqs;
 	unsigned int apic_irq_work_irqs;
diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
index eb92a6e..cebef02 100644
--- a/arch/x86/include/asm/hw_irq.h
+++ b/arch/x86/include/asm/hw_irq.h
@@ -28,6 +28,7 @@
 /* Interrupt handlers registered during init_IRQ */
 extern void apic_timer_interrupt(void);
 extern void x86_platform_ipi(void);
+extern void kvm_posted_intr_ipi(void);
 extern void error_interrupt(void);
 extern void irq_work_interrupt(void);
 
diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index 1508e51..774dc9f 100644
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -102,6 +102,11 @@
  */
 #define X86_PLATFORM_IPI_VECTOR		0xf7
 
+/* Vector for KVM to deliver posted interrupt IPI */
+#ifdef CONFIG_HAVE_KVM
+#define POSTED_INTR_VECTOR		0xf2
+#endif
+
 /*
  * IRQ work vector:
  */
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 70641af..781bc06 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1177,6 +1177,11 @@ apicinterrupt LOCAL_TIMER_VECTOR \
 apicinterrupt X86_PLATFORM_IPI_VECTOR \
 	x86_platform_ipi smp_x86_platform_ipi
 
+#ifdef CONFIG_HAVE_KVM
+apicinterrupt POSTED_INTR_VECTOR \
+	kvm_posted_intr_ipi smp_kvm_posted_intr_ipi
+#endif
+
 apicinterrupt THRESHOLD_APIC_VECTOR \
 	threshold_interrupt smp_threshold_interrupt
 apicinterrupt THERMAL_APIC_VECTOR \
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index e4595f1..6ae6ea1 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -228,6 +228,28 @@ void smp_x86_platform_ipi(struct pt_regs *regs)
 	set_irq_regs(old_regs);
 }
 
+#ifdef CONFIG_HAVE_KVM
+/*
+ * Handler for POSTED_INTERRUPT_VECTOR.
+ */
+void smp_kvm_posted_intr_ipi(struct pt_regs *regs)
+{
+	struct pt_regs *old_regs = set_irq_regs(regs);
+
+	ack_APIC_irq();
+
+	irq_enter();
+
+	exit_idle();
+
+	inc_irq_stat(kvm_posted_intr_ipis);
+
+	irq_exit();
+
+	set_irq_regs(old_regs);
+}
+#endif
+
 EXPORT_SYMBOL_GPL(vector_used_by_percpu_irq);
 
 #ifdef CONFIG_HOTPLUG_CPU
diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index 6e03b0d..2329a54 100644
--- a/arch/x86/kernel/irqinit.c
+++ b/arch/x86/kernel/irqinit.c
@@ -205,6 +205,10 @@ static void __init apic_intr_init(void)
 
 	/* IPI for X86 platform specific use */
 	alloc_intr_gate(X86_PLATFORM_IPI_VECTOR, x86_platform_ipi);
+#ifdef CONFIG_HAVE_KVM
+	/* IPI for KVM to deliver posted interrupt */
+	alloc_intr_gate(POSTED_INTR_VECTOR, kvm_posted_intr_ipi);
+#endif
 
 	/* IPI vectors for APIC spurious and error interrupts */
 	alloc_intr_gate(SPURIOUS_APIC_VECTOR, spurious_interrupt);
-- 
1.7.1