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

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Date:   Fri, 29 Jun 2018 17:51:15 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: [PATCH 1/2] KVM: X86: Implement PV IPI in linux guest

From: Wanpeng Li <wanpengli@...cent.com>

Implement PV IPIs in guest kernel.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: Vitaly Kuznetsov <vkuznets@...hat.com>
Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
---
 arch/x86/include/uapi/asm/kvm_para.h |  1 +
 arch/x86/kernel/kvm.c                | 63 ++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
index 0ede697..19980ec 100644
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -28,6 +28,7 @@
 #define KVM_FEATURE_PV_UNHALT		7
 #define KVM_FEATURE_PV_TLB_FLUSH	9
 #define KVM_FEATURE_ASYNC_PF_VMEXIT	10
+#define KVM_FEATURE_PV_SEND_IPI	11
 
 #define KVM_HINTS_REALTIME      0
 
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 5b2300b..b4f8dc3 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -454,6 +454,57 @@ static void __init sev_map_percpu_data(void)
 }
 
 #ifdef CONFIG_SMP
+
+static void __send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	unsigned long flags, ipi_bitmap = 0;
+	int cpu;
+
+	local_irq_save(flags);
+
+	for_each_cpu(cpu, mask)
+		__set_bit(per_cpu(x86_cpu_to_apicid, cpu), &ipi_bitmap);
+	kvm_hypercall2(KVM_HC_SEND_IPI, ipi_bitmap, vector);
+
+	local_irq_restore(flags);
+}
+
+static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	__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;
+	__send_ipi_mask(local_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)
+{
+	__send_ipi_mask(cpu_online_mask, vector);
+}
+
+static void kvm_setup_pv_ipi(void)
+{
+	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;
+	printk("KVM setup pv IPIs\n");
+}
+
 static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)
 {
 	native_smp_prepare_cpus(max_cpus);
@@ -624,12 +675,24 @@ static uint32_t __init kvm_detect(void)
 	return kvm_cpuid_base();
 }
 
+static void __init kvm_apic_init(void)
+{
+	if (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI))
+		kvm_setup_pv_ipi();
+}
+
+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)
-- 
2.7.4