On 07/14/2013 06:54 PM, Gleb Natapov wrote:

On Mon, Jun 24, 2013 at 06:13:53PM +0530, Raghavendra K T wrote:

quoted

Simplify kvm_for_each_vcpu with kvm_irq_delivery_to_apic

From: Raghavendra K T <redacted>

Note that we are using APIC_DM_REMRD which has reserved usage.
In future if APIC_DM_REMRD usage is standardized, then we should
find some other way or go back to old method.

Suggested-by: Gleb Natapov <redacted>
Signed-off-by: Raghavendra K T <redacted>
---
  arch/x86/kvm/lapic.c |    5 ++++-
  arch/x86/kvm/x86.c   |   25 ++++++-------------------
  2 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index e1adbb4..3f5f82e 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c

@@ -706,7 +706,10 @@ out:
  		break;

  	case APIC_DM_REMRD:
-		apic_debug("Ignoring delivery mode 3\n");
+		result = 1;
+		vcpu->arch.pv.pv_unhalted = 1;
+		kvm_make_request(KVM_REQ_EVENT, vcpu);
+		kvm_vcpu_kick(vcpu);
  		break;

  	case APIC_DM_SMI:

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 92a9932..b963c86 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c

@@ -5456,27 +5456,14 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
   */
  static void kvm_pv_kick_cpu_op(struct kvm *kvm, int apicid)
  {
-	struct kvm_vcpu *vcpu = NULL;
-	int i;
+	struct kvm_lapic_irq lapic_irq;

-	kvm_for_each_vcpu(i, vcpu, kvm) {
-		if (!kvm_apic_present(vcpu))
-			continue;
+	lapic_irq.shorthand = 0;
+	lapic_irq.dest_mode = 0;
+	lapic_irq.dest_id = apicid;

-		if (kvm_apic_match_dest(vcpu, 0, 0, apicid, 0))
-			break;
-	}
-	if (vcpu) {
-		/*
-		 * Setting unhalt flag here can result in spurious runnable
-		 * state when unhalt reset does not happen in vcpu_block.
-		 * But that is harmless since that should soon result in halt.
-		 */
-		vcpu->arch.pv.pv_unhalted = true;
-		/* We need everybody see unhalt before vcpu unblocks */
-		smp_wmb();
-		kvm_vcpu_kick(vcpu);
-	}
+	lapic_irq.delivery_mode = APIC_DM_REMRD;

Need to make sure that delivery_mode cannot be set to APIC_DM_REMRD
from MSI/IOAPIC/IPI path.

I Gleb,
I need your help here since I do not know much about apic.

so are you saying explicitly checking that, kvm_set_msi_irq, 
apic_send_ipi, native_setup_ioapic_entry, does not have APIC_DM_REMRD as 
delivery_mode set?