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From: Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
To: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
	yrl.pp-manager.tt@hitachi.com,
	Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>,
	Avi Kivity <avi@redhat.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>
Subject: [RFC v2 PATCH 14/21] KVM: Directly handle interrupts by guests without VM EXIT on slave CPUs
Date: Thu, 06 Sep 2012 20:28:32 +0900	[thread overview]
Message-ID: <20120906112832.13320.84430.stgit@kvmdev> (raw)
In-Reply-To: <20120906112718.13320.8231.stgit@kvmdev>

Make interrupts on slave CPUs handled by guests without VM EXIT.
This reduces CPU usage by the host to transfer interrupts of assigned
PCI devices from the host to guests. It also reduces cost of VM EXIT
and quickens response of guests to the interrupts.

When a slave CPU is dedicated to a vCPU, exit on external interrupts is
disabled. Unfortunately, we can only enable/disable exits for whole
external interrupts except NMIs and cannot switch exits based on IRQ#
or vectors. Thus, to avoid IPIs from online CPUs transferred to guests,
this patch modify kvm_vcpu_kick() to use NMI for guests on slave CPUs.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
---

 arch/x86/include/asm/kvm_host.h |    1 +
 arch/x86/kvm/lapic.c            |    5 +++++
 arch/x86/kvm/vmx.c              |   19 ++++++++++++++++++
 arch/x86/kvm/x86.c              |   41 +++++++++++++++++++++++++++++++++++++++
 include/linux/kvm_host.h        |    1 +
 virt/kvm/kvm_main.c             |    5 +++--
 6 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 5ce89f1..65242a6 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -725,6 +725,7 @@ struct kvm_x86_ops {
 			       struct x86_instruction_info *info,
 			       enum x86_intercept_stage stage);
 
+	void (*set_direct_interrupt)(struct kvm_vcpu *vcpu, bool enabled);
 	void (*set_slave_mode)(struct kvm_vcpu *vcpu, bool slave);
 };
 
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index ce87878..73f57f3 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -601,6 +601,9 @@ static int apic_set_eoi(struct kvm_lapic *apic)
 		kvm_ioapic_update_eoi(apic->vcpu->kvm, vector, trigger_mode);
 	}
 	kvm_make_request(KVM_REQ_EVENT, apic->vcpu);
+	if (vcpu_has_slave_cpu(apic->vcpu) &&
+	    kvm_x86_ops->set_direct_interrupt)
+		kvm_x86_ops->set_direct_interrupt(apic->vcpu, 1);
 	return vector;
 }
 
@@ -1569,6 +1572,8 @@ int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data)
 	u64 addr = data & ~KVM_MSR_ENABLED;
 	if (!IS_ALIGNED(addr, 4))
 		return 1;
+	if (vcpu_has_slave_cpu(vcpu))
+		return 1;
 
 	vcpu->arch.pv_eoi.msr_val = data;
 	if (!pv_eoi_enabled(vcpu))
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 03a2d02..605abea 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1711,6 +1711,16 @@ static inline void vmx_clear_hlt(struct kvm_vcpu *vcpu)
 #endif
 }
 
+static void vmx_set_direct_interrupt(struct kvm_vcpu *vcpu, bool enabled)
+{
+	if (enabled)
+		vmcs_clear_bits(PIN_BASED_VM_EXEC_CONTROL,
+				PIN_BASED_EXT_INTR_MASK);
+	else
+		vmcs_set_bits(PIN_BASED_VM_EXEC_CONTROL,
+			      PIN_BASED_EXT_INTR_MASK);
+}
+
 static void vmx_set_slave_mode(struct kvm_vcpu *vcpu, bool slave)
 {
 	/* Don't intercept the guest's halt on slave CPU */
@@ -1721,6 +1731,8 @@ static void vmx_set_slave_mode(struct kvm_vcpu *vcpu, bool slave)
 		vmcs_set_bits(CPU_BASED_VM_EXEC_CONTROL,
 			      CPU_BASED_HLT_EXITING);
 	}
+
+	vmx_set_direct_interrupt(vcpu, slave);
 }
 
 /*
@@ -1776,6 +1788,8 @@ static void vmx_queue_exception(struct kvm_vcpu *vcpu, unsigned nr,
 
 	vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr_info);
 	vmx_clear_hlt(vcpu);
+	if (vcpu_has_slave_cpu(vcpu))
+		vmx_set_direct_interrupt(vcpu, 0);
 }
 
 static bool vmx_rdtscp_supported(void)
@@ -4147,6 +4161,8 @@ static void vmx_inject_irq(struct kvm_vcpu *vcpu)
 		intr |= INTR_TYPE_EXT_INTR;
 	vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr);
 	vmx_clear_hlt(vcpu);
+	if (vcpu_has_slave_cpu(vcpu))
+		vmx_set_direct_interrupt(vcpu, 0);
 }
 
 static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
@@ -4179,6 +4195,8 @@ static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
 	vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
 			INTR_TYPE_NMI_INTR | INTR_INFO_VALID_MASK | NMI_VECTOR);
 	vmx_clear_hlt(vcpu);
+	if (vcpu_has_slave_cpu(vcpu))
+		vmx_set_direct_interrupt(vcpu, 0);
 }
 
 static int vmx_nmi_allowed(struct kvm_vcpu *vcpu)
@@ -7374,6 +7392,7 @@ static struct kvm_x86_ops vmx_x86_ops = {
 
 	.check_intercept = vmx_check_intercept,
 
+	.set_direct_interrupt = vmx_set_direct_interrupt,
 	.set_slave_mode = vmx_set_slave_mode,
 };
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a6b2521..b7d28df 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -63,6 +63,7 @@
 #include <asm/pvclock.h>
 #include <asm/div64.h>
 #include <asm/cpu.h>
+#include <asm/nmi.h>
 #include <asm/mmu.h>
 
 #define MAX_IO_MSRS 256
@@ -2664,6 +2665,8 @@ static int kvm_set_guest_paused(struct kvm_vcpu *vcpu)
 /* vcpu currently running on each slave CPU */
 static DEFINE_PER_CPU(struct kvm_vcpu *, slave_vcpu);
 
+static int kvm_arch_kicked_by_nmi(unsigned int cmd, struct pt_regs *regs);
+
 static int kvm_arch_vcpu_ioctl_set_slave_cpu(struct kvm_vcpu *vcpu,
 					     int slave, int set_slave_mode)
 {
@@ -5011,6 +5014,11 @@ int kvm_arch_init(void *opaque)
 	if (cpu_has_xsave)
 		host_xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
 
+#ifdef CONFIG_SLAVE_CPU
+	register_nmi_handler(NMI_LOCAL, kvm_arch_kicked_by_nmi, 0,
+			     "kvm_kick");
+#endif
+
 	return 0;
 
 out:
@@ -5026,6 +5034,9 @@ void kvm_arch_exit(void)
 					    CPUFREQ_TRANSITION_NOTIFIER);
 	unregister_hotcpu_notifier(&kvmclock_cpu_notifier_block);
 	unregister_slave_cpu_notifier(&kvmclock_slave_cpu_notifier_block);
+#ifdef CONFIG_SLAVE_CPU
+	unregister_nmi_handler(NMI_LOCAL, "kvm_kick");
+#endif
 	kvm_x86_ops = NULL;
 	kvm_mmu_module_exit();
 }
@@ -5322,6 +5333,27 @@ static void process_nmi(struct kvm_vcpu *vcpu)
 	kvm_make_request(KVM_REQ_EVENT, vcpu);
 }
 
+#ifdef CONFIG_SLAVE_CPU
+static int kvm_arch_kicked_by_nmi(unsigned int cmd, struct pt_regs *regs)
+{
+	struct kvm_vcpu *vcpu;
+	int cpu = smp_processor_id();
+
+	if (!cpu_slave(cpu))
+		return NMI_DONE;
+
+	vcpu = __this_cpu_read(slave_vcpu);
+	if (!vcpu)
+		return NMI_DONE;
+
+	/* if called from NMI handler after VM exit, no need to prevent run */
+	if (vcpu->mode == OUTSIDE_GUEST_MODE || kvm_is_in_guest())
+		return NMI_HANDLED;
+
+	return NMI_HANDLED;
+}
+#endif
+
 enum vcpu_enter_guest_slave_retval {
 	EXIT_TO_USER = 0,
 	LOOP_ONLINE,		/* vcpu_post_run is done in online cpu */
@@ -6706,6 +6738,15 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
 }
 
+int kvm_arch_vcpu_kick_slave(struct kvm_vcpu *vcpu)
+{
+	if (kvm_vcpu_exiting_guest_mode(vcpu) != OUTSIDE_GUEST_MODE) {
+		apic->send_IPI_mask(get_cpu_mask(vcpu->cpu), NMI_VECTOR);
+		return 1;
+	}
+	return 0;
+}
+
 int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu)
 {
 	return kvm_x86_ops->interrupt_allowed(vcpu);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a60743f..5fd9c64 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -539,6 +539,7 @@ void kvm_arch_hardware_unsetup(void);
 void kvm_arch_check_processor_compat(void *rtn);
 int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu);
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu);
+int kvm_arch_vcpu_kick_slave(struct kvm_vcpu *vcpu);
 
 void kvm_free_physmem(struct kvm *kvm);
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index debbee1..858b7a9 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1543,10 +1543,11 @@ void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
 	}
 
 	me = get_cpu();
-	if (cpu != me && (unsigned)cpu < nr_cpu_ids &&
-	    (cpu_online(cpu) || cpu_slave(cpu)))
+	if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu))
 		if (kvm_arch_vcpu_should_kick(vcpu))
 			smp_send_reschedule(cpu);
+	if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_slave(cpu))
+		kvm_arch_vcpu_kick_slave(vcpu);
 	put_cpu();
 }
 #endif /* !CONFIG_S390 */



  parent reply	other threads:[~2012-09-06 11:31 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-06 11:27 [RFC v2 PATCH 00/21] KVM: x86: CPU isolation and direct interrupts delivery to guests Tomoki Sekiyama
2012-09-06 11:27 ` [RFC v2 PATCH 01/21] x86: Split memory hotplug function from cpu_up() as cpu_memory_up() Tomoki Sekiyama
2012-09-06 11:31   ` Avi Kivity
2012-09-06 11:32     ` Avi Kivity
2012-09-06 11:27 ` [RFC v2 PATCH 02/21] x86: Add a facility to use offlined CPUs as slave CPUs Tomoki Sekiyama
2012-09-06 11:27 ` [RFC v2 PATCH 03/21] x86: Support hrtimer on " Tomoki Sekiyama
2012-09-06 11:27 ` [RFC v2 PATCH 04/21] x86: Avoid RCU warnings " Tomoki Sekiyama
2012-09-20 17:34   ` Paul E. McKenney
2012-09-28  8:10     ` Tomoki Sekiyama
2012-09-06 11:27 ` [RFC v2 PATCH 05/21] KVM: Enable/Disable virtualization on slave CPUs are activated/dying Tomoki Sekiyama
2012-09-06 11:27 ` [RFC v2 PATCH 06/21] KVM: Add facility to run guests on slave CPUs Tomoki Sekiyama
2012-09-06 11:27 ` [RFC v2 PATCH 07/21] KVM: handle page faults of slave guests on online CPUs Tomoki Sekiyama
2012-09-06 11:28 ` [RFC v2 PATCH 08/21] KVM: Add KVM_GET_SLAVE_CPU and KVM_SET_SLAVE_CPU to vCPU ioctl Tomoki Sekiyama
2012-09-06 11:28 ` [RFC v2 PATCH 09/21] KVM: Go back to online CPU on VM exit by external interrupt Tomoki Sekiyama
2012-09-06 11:28 ` [RFC v2 PATCH 10/21] KVM: proxy slab operations for slave CPUs on online CPUs Tomoki Sekiyama
2012-09-06 11:28 ` [RFC v2 PATCH 11/21] KVM: no exiting from guest when slave CPU halted Tomoki Sekiyama
2012-09-06 11:28 ` [RFC v2 PATCH 12/21] x86/apic: Enable external interrupt routing to slave CPUs Tomoki Sekiyama
2012-09-06 11:28 ` [RFC v2 PATCH 13/21] x86/apic: IRQ vector remapping on slave for " Tomoki Sekiyama
2012-09-06 11:28 ` Tomoki Sekiyama [this message]
2012-09-06 11:28 ` [RFC v2 PATCH 15/21] KVM: add tracepoint on enabling/disabling direct interrupt delivery Tomoki Sekiyama
2012-09-06 11:28 ` [RFC v2 PATCH 16/21] KVM: vmx: Add definitions PIN_BASED_PREEMPTION_TIMER Tomoki Sekiyama
2012-09-06 11:28 ` [RFC v2 PATCH 17/21] KVM: add kvm_arch_vcpu_prevent_run to prevent VM ENTER when NMI is received Tomoki Sekiyama
2012-09-06 11:28 ` [RFC v2 PATCH 18/21] KVM: route assigned devices' MSI/MSI-X directly to guests on slave CPUs Tomoki Sekiyama
2012-09-06 11:28 ` [RFC v2 PATCH 19/21] KVM: Enable direct EOI for directly routed interrupts to guests Tomoki Sekiyama
2012-09-06 11:29 ` [RFC v2 PATCH 20/21] KVM: Pass-through local APIC timer of on slave CPUs to guest VM Tomoki Sekiyama
2012-09-06 11:29 ` [RFC v2 PATCH 21/21] x86: request TLB flush to slave CPU using NMI Tomoki Sekiyama
2012-09-06 11:46 ` [RFC v2 PATCH 00/21] KVM: x86: CPU isolation and direct interrupts delivery to guests Avi Kivity
2012-09-07  8:26 ` Jan Kiszka
2012-09-10 11:36   ` Tomoki Sekiyama

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