[RFC PATCH 04/41] perf: core/x86: Add support to register a new vector for PMI handling

[Xiong Zhang]

From: Xiong Zhang <xiong.y.zhang@xxxxxxxxx>

Create a new vector in the host IDT for PMI handling within a passthrough
vPMU implementation. In addition, add a function to allow the registration
of the handler and a function to switch the PMI handler.

This is the preparation work to support KVM passthrough vPMU to handle its
own PMIs without interference from PMI handler of the host PMU.

Signed-off-by: Xiong Zhang <xiong.y.zhang@xxxxxxxxx>
Signed-off-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
---
 arch/x86/include/asm/hardirq.h           |  1 +
 arch/x86/include/asm/idtentry.h          |  1 +
 arch/x86/include/asm/irq.h               |  1 +
 arch/x86/include/asm/irq_vectors.h       |  2 +-
 arch/x86/kernel/idt.c                    |  1 +
 arch/x86/kernel/irq.c                    | 29 ++++++++++++++++++++++++
 tools/arch/x86/include/asm/irq_vectors.h |  1 +
 7 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h
index 66837b8c67f1..c1e2c1a480bf 100644
--- a/arch/x86/include/asm/hardirq.h
+++ b/arch/x86/include/asm/hardirq.h
@@ -19,6 +19,7 @@ typedef struct {
 	unsigned int kvm_posted_intr_ipis;
 	unsigned int kvm_posted_intr_wakeup_ipis;
 	unsigned int kvm_posted_intr_nested_ipis;
+	unsigned int kvm_vpmu_pmis;
 #endif
 	unsigned int x86_platform_ipis;	/* arch dependent */
 	unsigned int apic_perf_irqs;
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 05fd175cec7d..d1b58366bc21 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -675,6 +675,7 @@ DECLARE_IDTENTRY_SYSVEC(IRQ_WORK_VECTOR,		sysvec_irq_work);
 DECLARE_IDTENTRY_SYSVEC(POSTED_INTR_VECTOR,		sysvec_kvm_posted_intr_ipi);
 DECLARE_IDTENTRY_SYSVEC(POSTED_INTR_WAKEUP_VECTOR,	sysvec_kvm_posted_intr_wakeup_ipi);
 DECLARE_IDTENTRY_SYSVEC(POSTED_INTR_NESTED_VECTOR,	sysvec_kvm_posted_intr_nested_ipi);
+DECLARE_IDTENTRY_SYSVEC(KVM_VPMU_VECTOR,	        sysvec_kvm_vpmu_handler);
 #endif
 
 #if IS_ENABLED(CONFIG_HYPERV)
diff --git a/arch/x86/include/asm/irq.h b/arch/x86/include/asm/irq.h
index 836c170d3087..ee268f42d04a 100644
--- a/arch/x86/include/asm/irq.h
+++ b/arch/x86/include/asm/irq.h
@@ -31,6 +31,7 @@ extern void fixup_irqs(void);
 
 #ifdef CONFIG_HAVE_KVM
 extern void kvm_set_posted_intr_wakeup_handler(void (*handler)(void));
+extern void kvm_set_vpmu_handler(void (*handler)(void));
 #endif
 
 extern void (*x86_platform_ipi_callback)(void);
diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index 3a19904c2db6..120403572307 100644
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -77,7 +77,7 @@
  */
 #define IRQ_WORK_VECTOR			0xf6
 
-/* 0xf5 - unused, was UV_BAU_MESSAGE */
+#define KVM_VPMU_VECTOR			0xf5
 #define DEFERRED_ERROR_VECTOR		0xf4
 
 /* Vector on which hypervisor callbacks will be delivered */
diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index 8857abc706e4..6944eec251f4 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -157,6 +157,7 @@ static const __initconst struct idt_data apic_idts[] = {
 	INTG(POSTED_INTR_VECTOR,		asm_sysvec_kvm_posted_intr_ipi),
 	INTG(POSTED_INTR_WAKEUP_VECTOR,		asm_sysvec_kvm_posted_intr_wakeup_ipi),
 	INTG(POSTED_INTR_NESTED_VECTOR,		asm_sysvec_kvm_posted_intr_nested_ipi),
+	INTG(KVM_VPMU_VECTOR,		        asm_sysvec_kvm_vpmu_handler),
 # endif
 # ifdef CONFIG_IRQ_WORK
 	INTG(IRQ_WORK_VECTOR,			asm_sysvec_irq_work),
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 11761c124545..c6cffb34191b 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -181,6 +181,13 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 		seq_printf(p, "%10u ",
 			   irq_stats(j)->kvm_posted_intr_wakeup_ipis);
 	seq_puts(p, "  Posted-interrupt wakeup event\n");
+
+	seq_printf(p, "%*s: ", prec, "VPMU");
+	for_each_online_cpu(j)
+		seq_printf(p, "%10u ",
+			   irq_stats(j)->kvm_vpmu_pmis);
+	seq_puts(p, " PT PMU PMI\n");
+
 #endif
 	return 0;
 }
@@ -293,6 +300,7 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_x86_platform_ipi)
 #ifdef CONFIG_HAVE_KVM
 static void dummy_handler(void) {}
 static void (*kvm_posted_intr_wakeup_handler)(void) = dummy_handler;
+static void (*kvm_vpmu_handler)(void) = dummy_handler;
 
 void kvm_set_posted_intr_wakeup_handler(void (*handler)(void))
 {
@@ -305,6 +313,17 @@ void kvm_set_posted_intr_wakeup_handler(void (*handler)(void))
 }
 EXPORT_SYMBOL_GPL(kvm_set_posted_intr_wakeup_handler);
 
+void kvm_set_vpmu_handler(void (*handler)(void))
+{
+	if (handler)
+		kvm_vpmu_handler = handler;
+	else {
+		kvm_vpmu_handler = dummy_handler;
+		synchronize_rcu();
+	}
+}
+EXPORT_SYMBOL_GPL(kvm_set_vpmu_handler);
+
 /*
  * Handler for POSTED_INTERRUPT_VECTOR.
  */
@@ -332,6 +351,16 @@ DEFINE_IDTENTRY_SYSVEC_SIMPLE(sysvec_kvm_posted_intr_nested_ipi)
 	apic_eoi();
 	inc_irq_stat(kvm_posted_intr_nested_ipis);
 }
+
+/*
+ * Handler for KVM_PT_PMU_VECTOR.
+ */
+DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_vpmu_handler)
+{
+	apic_eoi();
+	inc_irq_stat(kvm_vpmu_pmis);
+	kvm_vpmu_handler();
+}
 #endif
 
 
diff --git a/tools/arch/x86/include/asm/irq_vectors.h b/tools/arch/x86/include/asm/irq_vectors.h
index 3a19904c2db6..3773e60f1af8 100644
--- a/tools/arch/x86/include/asm/irq_vectors.h
+++ b/tools/arch/x86/include/asm/irq_vectors.h
@@ -85,6 +85,7 @@
 
 /* Vector for KVM to deliver posted interrupt IPI */
 #ifdef CONFIG_HAVE_KVM
+#define KVM_VPMU_VECTOR			0xf5
 #define POSTED_INTR_VECTOR		0xf2
 #define POSTED_INTR_WAKEUP_VECTOR	0xf1
 #define POSTED_INTR_NESTED_VECTOR	0xf0
-- 
2.34.1