[v4 12/16] KVM: kvm-vfio: implement the VFIO skeleton for VT-d Posted-Interrupts

[Feng Wu <feng.wu@intel.com>]

This patch adds the kvm-vfio interface for VT-d Posted-Interrupts.
When guests update MSI/MSI-x information for an assigned-device,
QEMU will use KVM_DEV_VFIO_DEVICE_POST_IRQ attribute to setup
IRTE for VT-d PI. Userspace program can also use
KVM_DEV_VFIO_DEVICE_UNPOST_IRQ to change back to irq remapping mode.
This patch implements these IRQ attributes.

Signed-off-by: Feng Wu <feng.wu@intel.com>
---
 include/linux/kvm_host.h |  22 +++++++++
 virt/kvm/vfio.c          | 126 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 148 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index f591f7c..69f8711 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1073,6 +1073,28 @@ extern struct kvm_device_ops kvm_xics_ops;
 extern struct kvm_device_ops kvm_arm_vgic_v2_ops;
 extern struct kvm_device_ops kvm_arm_vgic_v3_ops;
 
+#ifdef __KVM_HAVE_ARCH_KVM_VFIO_POST
+/*
+ * kvm_arch_vfio_update_pi_irte - set IRTE for Posted-Interrupts
+ *
+ * @kvm: kvm
+ * @host_irq: host irq of the interrupt
+ * @guest_irq: gsi of the interrupt
+ * @set: set or unset PI
+ * returns 0 on success, < 0 on failure
+ */
+int kvm_arch_vfio_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
+				 uint32_t guest_irq, bool set);
+#else
+static inline int kvm_arch_vfio_update_pi_irte(struct kvm *kvm,
+					       unsigned int host_irq,
+					       uint32_t guest_irq,
+					       bool set)
+{
+	return 0;
+}
+#endif
+
 #ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
 
 static inline void kvm_vcpu_set_in_spin_loop(struct kvm_vcpu *vcpu, bool val)
diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 80a45e4..547fc51 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -18,6 +18,7 @@
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/vfio.h>
+#include <asm/irq_remapping.h>
 #include "vfio.h"
 
 struct kvm_vfio_group {
@@ -276,12 +277,128 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
 	return -ENXIO;
 }
 
+static int kvm_vfio_pci_get_irq_count(struct pci_dev *pdev, int irq_type)
+{
+	if (irq_type == VFIO_PCI_INTX_IRQ_INDEX) {
+		u8 pin;
+
+		pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
+		if (pin)
+			return 1;
+	} else if (irq_type == VFIO_PCI_MSI_IRQ_INDEX) {
+		return pci_msi_vec_count(pdev);
+	} else if (irq_type == VFIO_PCI_MSIX_IRQ_INDEX) {
+		return pci_msix_vec_count(pdev);
+	}
+
+	return 0;
+}
+
+static int kvm_vfio_control_pi(struct kvm_device *kdev,
+			       int32_t __user *argp, bool set)
+{
+	struct kvm_vfio_dev_irq pi_info;
+	uint32_t *gsi;
+	unsigned long minsz;
+	struct vfio_device *vdev;
+	struct msi_desc *entry;
+	struct device *dev;
+	struct pci_dev *pdev;
+	int i, max, ret;
+
+	minsz = offsetofend(struct kvm_vfio_dev_irq, count);
+
+	if (copy_from_user(&pi_info, (void __user *)argp, minsz))
+		return -EFAULT;
+
+	if (pi_info.argsz < minsz || pi_info.index >= VFIO_PCI_NUM_IRQS)
+		return -EINVAL;
+
+	vdev = kvm_vfio_get_vfio_device(pi_info.fd);
+	if (IS_ERR(vdev))
+		return PTR_ERR(vdev);
+
+	dev = kvm_vfio_external_base_device(vdev);
+	if (!dev || !dev_is_pci(dev)) {
+		ret = -EFAULT;
+		goto put_vfio_device;
+	}
+
+	pdev = to_pci_dev(dev);
+
+	max = kvm_vfio_pci_get_irq_count(pdev, pi_info.index);
+	if (max <= 0) {
+		ret = -EFAULT;
+		goto put_vfio_device;
+	}
+
+	if (pi_info.argsz - minsz < pi_info.count * sizeof(u32) ||
+	    pi_info.start >= max || pi_info.start + pi_info.count > max) {
+		ret = -EINVAL;
+		goto put_vfio_device;
+	}
+
+	gsi = memdup_user((void __user *)((unsigned long)argp + minsz),
+			   pi_info.count * sizeof(u32));
+	if (IS_ERR(gsi)) {
+		ret = PTR_ERR(gsi);
+		goto put_vfio_device;
+	}
+
+#ifdef CONFIG_PCI_MSI
+	for (i = 0; i < pi_info.count; i++) {
+		list_for_each_entry(entry, &pdev->msi_list, list) {
+			if (entry->msi_attrib.entry_nr != pi_info.start+i)
+				continue;
+
+			ret = kvm_arch_vfio_update_pi_irte(kdev->kvm,
+							   entry->irq,
+							   gsi[i],
+							   set);
+			if (ret)
+				goto free_gsi;
+		}
+	}
+#endif
+
+	ret = 0;
+
+free_gsi:
+	kfree(gsi);
+
+put_vfio_device:
+	kvm_vfio_put_vfio_device(vdev);
+	return ret;
+}
+
+static int kvm_vfio_set_device(struct kvm_device *kdev, long attr, u64 arg)
+{
+	int32_t __user *argp = (int32_t __user *)(unsigned long)arg;
+	int ret;
+
+	switch (attr) {
+#ifdef __KVM_HAVE_ARCH_KVM_VFIO_POST
+	case KVM_DEV_VFIO_DEVICE_POST_IRQ:
+		ret = kvm_vfio_control_pi(kdev, argp, 1);
+		break;
+	case KVM_DEV_VFIO_DEVICE_UNPOST_IRQ:
+		ret = kvm_vfio_control_pi(kdev, argp, 0);
+		break;
+#endif
+	default:
+		ret = -ENXIO;
+	}
+	return ret;
+}
+
 static int kvm_vfio_set_attr(struct kvm_device *dev,
 			     struct kvm_device_attr *attr)
 {
 	switch (attr->group) {
 	case KVM_DEV_VFIO_GROUP:
 		return kvm_vfio_set_group(dev, attr->attr, attr->addr);
+	case KVM_DEV_VFIO_DEVICE:
+		return kvm_vfio_set_device(dev, attr->attr, attr->addr);
 	}
 
 	return -ENXIO;
@@ -299,6 +416,15 @@ static int kvm_vfio_has_attr(struct kvm_device *dev,
 		}
 
 		break;
+	case KVM_DEV_VFIO_DEVICE:
+		switch (attr->attr) {
+#ifdef __KVM_HAVE_ARCH_KVM_VFIO_POST
+		case KVM_DEV_VFIO_DEVICE_POST_IRQ:
+		case KVM_DEV_VFIO_DEVICE_UNPOST_IRQ:
+			return irq_remapping_cap(IRQ_POSTING_CAP) ? 0 : -ENXIO;
+#endif
+		}
+		break;
 	}
 
 	return -ENXIO;
-- 
2.1.0