[PATCH v2 1/2] KVM: X86: Implement PV IPI in linux guest

[Wanpeng Li]

From: Wanpeng Li <wanpengli@xxxxxxxxxxx>

Implement PV IPIs in guest kernel.

Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
---
 arch/x86/kernel/kvm.c         | 99 +++++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/kvm_para.h |  1 +
 2 files changed, 100 insertions(+)

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 5b2300b..7e3ee25 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -47,6 +47,7 @@
 #include <asm/hypervisor.h>
 #include <asm/kvm_guest.h>
 
+static struct apic orig_apic;
 static int kvmapf = 1;
 
 static int __init parse_no_kvmapf(char *arg)
@@ -454,6 +455,89 @@ static void __init sev_map_percpu_data(void)
 }
 
 #ifdef CONFIG_SMP
+
+#ifdef CONFIG_X86_64
+static bool __send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	unsigned long flags, ipi_bitmap_low = 0, ipi_bitmap_high = 0, icr = 0;
+	int cpu, apic_id, ret = 1;
+
+	if (cpumask_empty(mask))
+		return true;
+
+	local_irq_save(flags);
+
+	for_each_cpu(cpu, mask) {
+		apic_id = per_cpu(x86_cpu_to_apicid, cpu);
+		if (apic_id < BITS_PER_LONG)
+			__set_bit(apic_id, &ipi_bitmap_low);
+		else if (apic_id < 2 * BITS_PER_LONG)
+			__set_bit(apic_id - BITS_PER_LONG, &ipi_bitmap_high);
+		else
+			goto ipi_mask_done;
+	}
+
+	switch (vector) {
+	default:
+		icr = APIC_DM_FIXED | vector;
+		break;
+	case NMI_VECTOR:
+		icr = APIC_DM_NMI;
+		break;
+	}
+
+	ret = kvm_hypercall3(KVM_HC_SEND_IPI, ipi_bitmap_low, ipi_bitmap_high, icr);
+
+ipi_mask_done:
+	local_irq_restore(flags);
+	return ((ret == 0) ? true : false);
+}
+
+static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	if (!__send_ipi_mask(mask, vector))
+		orig_apic.send_IPI_mask(mask, vector);
+}
+
+static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
+{
+	unsigned int this_cpu = smp_processor_id();
+	struct cpumask new_mask;
+	const struct cpumask *local_mask;
+
+	cpumask_copy(&new_mask, mask);
+	cpumask_clear_cpu(this_cpu, &new_mask);
+	local_mask = &new_mask;
+	if (!__send_ipi_mask(local_mask, vector))
+		orig_apic.send_IPI_mask_allbutself(mask, vector);
+}
+
+static void kvm_send_ipi_allbutself(int vector)
+{
+	kvm_send_ipi_mask_allbutself(cpu_online_mask, vector);
+}
+
+static void kvm_send_ipi_all(int vector)
+{
+	if (!__send_ipi_mask(cpu_online_mask, vector))
+		orig_apic.send_IPI_all(vector);
+}
+
+/*
+ * Set the IPI entry points
+ */
+static void kvm_setup_pv_ipi(void)
+{
+	orig_apic = *apic;
+
+	apic->send_IPI_mask = kvm_send_ipi_mask;
+	apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
+	apic->send_IPI_allbutself = kvm_send_ipi_allbutself;
+	apic->send_IPI_all = kvm_send_ipi_all;
+	pr_info("KVM setup pv IPIs\n");
+}
+#endif
+
 static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)
 {
 	native_smp_prepare_cpus(max_cpus);
@@ -624,12 +708,27 @@ static uint32_t __init kvm_detect(void)
 	return kvm_cpuid_base();
 }
 
+static void __init kvm_apic_init(void)
+{
+#if defined(CONFIG_SMP) && defined(CONFIG_X86_64)
+	if (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) &&
+		num_possible_cpus() <= 2 * BITS_PER_LONG)
+		kvm_setup_pv_ipi();
+#endif
+}
+
+static void __init kvm_init_platform(void)
+{
+	x86_platform.apic_post_init = kvm_apic_init;
+}
+
 const __initconst struct hypervisor_x86 x86_hyper_kvm = {
 	.name			= "KVM",
 	.detect			= kvm_detect,
 	.type			= X86_HYPER_KVM,
 	.init.guest_late_init	= kvm_guest_init,
 	.init.x2apic_available	= kvm_para_available,
+	.init.init_platform	= kvm_init_platform,
 };
 
 static __init int activate_jump_labels(void)
diff --git a/include/uapi/linux/kvm_para.h b/include/uapi/linux/kvm_para.h
index dcf629d..7395f38 100644
--- a/include/uapi/linux/kvm_para.h
+++ b/include/uapi/linux/kvm_para.h
@@ -26,6 +26,7 @@
 #define KVM_HC_MIPS_EXIT_VM		7
 #define KVM_HC_MIPS_CONSOLE_OUTPUT	8
 #define KVM_HC_CLOCK_PAIRING		9
+#define KVM_HC_SEND_IPI			10
 
 /*
  * hypercalls use architecture specific
-- 
2.7.4