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>
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index ae7a12c..73f3480 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -550,6 +550,7 @@
#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 f83ef9c..04401e1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -343,6 +343,14 @@
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 @@
{
int r = 0;
struct kvm_assigned_dev_kernel *match;
+ u32 current_flags = 0, changed_flags;
mutex_lock(&kvm->lock);
@@ -416,8 +425,13 @@
}
}
- 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);