[PATCH 11/11] KVM: MSI to INTx translate

[Sheng Yang <sheng@linux.intel.com>]

Now we use MSI as default one, and translate MSI to INTx when guest need
INTx rather than MSI. For legacy device, we provide support for non-sharing
host IRQ.

Provide a parameter msi2intx for this method. The value is true by default.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
---
 virt/kvm/kvm_main.c |   67 ++++++++++++++++++++++++++++++++++++++------------
 1 files changed, 51 insertions(+), 16 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8e0b599..98f145d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -64,6 +64,9 @@
 MODULE_AUTHOR("Qumranet");
 MODULE_LICENSE("GPL");
 
+static int msi2intx = 1;
+module_param(msi2intx, bool, 0);
+
 DEFINE_SPINLOCK(kvm_lock);
 LIST_HEAD(vm_list);
 
@@ -249,7 +252,8 @@ static int assigned_device_update_intx(struct kvm *kvm,
 		return 0;
 
 	if (irqchip_in_kernel(kvm)) {
-		if (adev->irq_requested_type & KVM_ASSIGNED_DEV_HOST_MSI) {
+		if (!msi2intx &&
+		    adev->irq_requested_type & KVM_ASSIGNED_DEV_HOST_MSI) {
 			free_irq(adev->host_irq, (void *)kvm);
 			pci_disable_msi(adev->dev);
 		}
@@ -284,21 +288,33 @@ static int assigned_device_update_msi(struct kvm *kvm,
 {
 	int r;
 
-	/* x86 don't care upper address of guest msi message addr */
-	adev->guest_msi.address_lo = airq->guest_msi.addr_lo;
-	adev->guest_msi.data = airq->guest_msi.data;
-	adev->ack_notifier.gsi = -1;
+	if (airq->flags & KVM_DEV_IRQ_ASSIGN_ENABLE_MSI) {
+		/* x86 don't care upper address of guest msi message addr */
+		adev->irq_requested_type |= KVM_ASSIGNED_DEV_GUEST_MSI;
+		adev->irq_requested_type &= ~KVM_ASSIGNED_DEV_GUEST_INTX;
+		adev->guest_msi.address_lo = airq->guest_msi.addr_lo;
+		adev->guest_msi.data = airq->guest_msi.data;
+		adev->ack_notifier.gsi = -1;
+	} else if (msi2intx) {
+		adev->irq_requested_type |= KVM_ASSIGNED_DEV_GUEST_INTX;
+		adev->irq_requested_type &= ~KVM_ASSIGNED_DEV_GUEST_MSI;
+		adev->guest_irq = airq->guest_irq;
+		adev->ack_notifier.gsi = airq->guest_irq;
+	}
 
 	if (adev->irq_requested_type & KVM_ASSIGNED_DEV_HOST_MSI)
 		return 0;
 
 	if (irqchip_in_kernel(kvm)) {
-		if (adev->irq_requested_type & KVM_ASSIGNED_DEV_HOST_INTX)
-			free_irq(adev->host_irq, (void *)adev);
-
-		r = pci_enable_msi(adev->dev);
-		if (r)
-			return r;
+		if (!msi2intx) {
+			if (adev->irq_requested_type &
+					KVM_ASSIGNED_DEV_HOST_INTX)
+				free_irq(adev->host_irq, (void *)adev);
+
+			r = pci_enable_msi(adev->dev);
+			if (r)
+				return r;
+		}
 
 		adev->host_irq = adev->dev->irq;
 		if (request_irq(adev->host_irq, kvm_assigned_dev_intr, 0,
@@ -306,8 +322,10 @@ static int assigned_device_update_msi(struct kvm *kvm,
 			return -EIO;
 	}
 
-	adev->irq_requested_type = KVM_ASSIGNED_DEV_GUEST_MSI |
-				   KVM_ASSIGNED_DEV_HOST_MSI;
+	if (!msi2intx)
+		adev->irq_requested_type = KVM_ASSIGNED_DEV_GUEST_MSI;
+
+	adev->irq_requested_type |= KVM_ASSIGNED_DEV_HOST_MSI;
 	return 0;
 }
 #endif
@@ -345,10 +363,19 @@ static int kvm_vm_ioctl_assign_irq(struct kvm *kvm,
 				goto out_release;
 			else
 				match->irq_source_id = r;
+
+#ifdef CONFIG_X86
+			/* Determine host device irq type, we can know the
+			 * result from dev->msi_enabled */
+			if (msi2intx)
+				pci_enable_msi(match->dev);
+#endif
 		}
 	}
 
-	if (assigned_irq->flags & KVM_DEV_IRQ_ASSIGN_ENABLE_MSI) {
+	if ((!msi2intx &&
+	     (assigned_irq->flags & KVM_DEV_IRQ_ASSIGN_ENABLE_MSI)) ||
+	    (msi2intx && match->dev->msi_enabled)) {
 #ifdef CONFIG_X86
 		r = assigned_device_update_msi(kvm, match, assigned_irq);
 		if (r) {
@@ -361,8 +388,16 @@ static int kvm_vm_ioctl_assign_irq(struct kvm *kvm,
 #endif
 	} else if (assigned_irq->host_irq == 0 && match->dev->irq == 0) {
 		/* Host device IRQ 0 means don't support INTx */
-		printk(KERN_WARNING "kvm: wait device to enable MSI!\n");
-		r = 0;
+		if (!msi2intx) {
+			printk(KERN_WARNING
+			       "kvm: wait device to enable MSI!\n");
+			r = 0;
+		} else {
+			printk(KERN_WARNING
+			       "kvm: failed to enable MSI device!\n");
+			r = -ENOTTY;
+			goto out_release;
+		}
 	} else {
 		/* Non-sharing INTx mode */
 		r = assigned_device_update_intx(kvm, match, assigned_irq);
-- 
1.5.4.5