From fa279fee2cd88aa0283b7e410eaf5ccfe1b73e1c Mon Sep 17 00:00:00 2001
From: Sheng Yang <sheng@linux.intel.com>
Date: Thu, 21 May 2009 17:09:38 -0700
Subject: [PATCH 01/12] KVM: Add support to disable MSI for assigned device

MSI is always enabled by default for msi2intx=1. But if msi2intx=0, we
have to disable MSI if guest require to do so.

The patch also discard unnecessary msi2intx judgment if guest want to update
MSI state.

Notice KVM_DEV_IRQ_ASSIGN_MSI_ACTION is a mask which should cover all MSI
related operations, though we only got one for now.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
(cherry picked from commit 46edd6f5b87aa6b8294f91d6f1213e00a4a59801)
Signed-off-by: Chris Wright <chrisw@redhat.com>
Bugzilla: 498084
Message-Id: <1242950989-30198-3-git-send-email-chrisw@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
RH-Upstream-status: applied
Acked-by: Juan Quintela <quintela@redhat.com>
Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
Acked-by: Don Dutile <ddutile@redhat.com>
---
 include/linux/kvm.h |    1 +
 virt/kvm/kvm_main.c |   18 ++++++++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 89baafb..6e18003 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -534,6 +534,7 @@ struct kvm_assigned_irq {
 
 #define KVM_DEV_ASSIGN_ENABLE_IOMMU	(1 << 0)
 
+#define KVM_DEV_IRQ_ASSIGN_MSI_ACTION	KVM_DEV_IRQ_ASSIGN_ENABLE_MSI
 #define KVM_DEV_IRQ_ASSIGN_ENABLE_MSI	(1 << 0)
 
 #endif
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 68e5b2d..1e70885 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -343,6 +343,14 @@ static int assigned_device_update_msi(struct kvm *kvm,
 		adev->irq_requested_type &= ~KVM_ASSIGNED_DEV_GUEST_MSI;
 		adev->guest_irq = airq->guest_irq;
 		adev->ack_notifier.gsi = airq->guest_irq;
+	} else {
+		/*
+		 * Guest require to disable device MSI, we disable MSI and
+		 * re-enable INTx by default again. Notice it's only for
+		 * non-msi2intx.
+		 */
+		assigned_device_update_intx(kvm, adev, airq);
+		return 0;
 	}
 
 	if (adev->irq_requested_type & KVM_ASSIGNED_DEV_HOST_MSI)
@@ -379,6 +387,7 @@ static int kvm_vm_ioctl_assign_irq(struct kvm *kvm,
 {
 	int r = 0;
 	struct kvm_assigned_dev_kernel *match;
+	u32 current_flags = 0, changed_flags;
 
 	mutex_lock(&kvm->lock);
 
@@ -416,8 +425,13 @@ static int kvm_vm_ioctl_assign_irq(struct kvm *kvm,
 		}
 	}
 
-	if ((!msi2intx &&
-	     (assigned_irq->flags & KVM_DEV_IRQ_ASSIGN_ENABLE_MSI)) ||
+	if ((match->irq_requested_type & KVM_ASSIGNED_DEV_HOST_MSI) &&
+		 (match->irq_requested_type & KVM_ASSIGNED_DEV_GUEST_MSI))
+		current_flags |= KVM_DEV_IRQ_ASSIGN_ENABLE_MSI;
+
+	changed_flags = assigned_irq->flags ^ current_flags;
+
+	if ((changed_flags & KVM_DEV_IRQ_ASSIGN_MSI_ACTION) ||
 	    (msi2intx && match->dev->msi_enabled)) {
 #ifdef CONFIG_X86
 		r = assigned_device_update_msi(kvm, match, assigned_irq);
-- 
1.6.3.rc4.29.g8146