[PATCH 7/8] KVM: assigned dev: Introduce io_device for MSI-X MMIO accessing

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

It would be work with KVM_CAP_DEVICE_MSIX_MASK, which we would enable in the
last patch.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
---
 include/linux/kvm.h      |    7 +++
 include/linux/kvm_host.h |    2 +
 virt/kvm/assigned-dev.c  |  131 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 140 insertions(+), 0 deletions(-)

diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index a699ec9..0a7bd34 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -798,4 +798,11 @@ struct kvm_assigned_msix_entry {
 	__u16 padding[2];
 };
 
+struct kvm_assigned_msix_mmio {
+	__u32 assigned_dev_id;
+	__u64 base_addr;
+	__u32 flags;
+	__u32 reserved[2];
+};
+
 #endif /* __LINUX_KVM_H */
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 81a6284..b67082f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -465,6 +465,8 @@ struct kvm_assigned_dev_kernel {
 	struct pci_dev *dev;
 	struct kvm *kvm;
 	spinlock_t assigned_dev_lock;
+	u64 msix_mmio_base;
+	struct kvm_io_device msix_mmio_dev;
 };
 
 struct kvm_irq_mask_notifier {
diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index bf96ea7..5d2adc4 100644
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -739,6 +739,137 @@ msix_entry_out:
 
 	return r;
 }
+
+static bool msix_mmio_in_range(struct kvm_assigned_dev_kernel *adev,
+			      gpa_t addr, int len, int *idx)
+{
+	int i;
+
+	if (!(adev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX))
+		return false;
+	BUG_ON(adev->msix_mmio_base == 0);
+	for (i = 0; i < adev->entries_nr; i++) {
+		u64 start, end;
+		start = adev->msix_mmio_base +
+			adev->guest_msix_entries[i].entry * PCI_MSIX_ENTRY_SIZE;
+		end = start + PCI_MSIX_ENTRY_SIZE;
+		if (addr >= start && addr + len <= end) {
+			*idx = i;
+			return true;
+		}
+	}
+	return false;
+}
+
+static int msix_mmio_read(struct kvm_io_device *this, gpa_t addr, int len,
+			  void *val)
+{
+	struct kvm_assigned_dev_kernel *adev =
+			container_of(this, struct kvm_assigned_dev_kernel,
+				     msix_mmio_dev);
+	int idx, r = 0;
+	u32 entry[4];
+	struct kvm_kernel_irq_routing_entry *e;
+
+	mutex_lock(&adev->kvm->lock);
+	if (!msix_mmio_in_range(adev, addr, len, &idx)) {
+		r = -EOPNOTSUPP;
+		goto out;
+	}
+	if ((addr & 0x3) || len != 4) {
+		printk(KERN_WARNING
+			"KVM: Unaligned reading for device MSI-X MMIO! "
+			"addr 0x%llx, len %d\n", addr, len);
+		r = -EOPNOTSUPP;
+		goto out;
+	}
+
+	e = kvm_get_irq_routing_entry(adev->kvm,
+			adev->guest_msix_entries[idx].vector);
+	if (!e || e->type != KVM_IRQ_ROUTING_MSI) {
+		printk(KERN_WARNING "KVM: Wrong MSI-X routing entry! "
+			"addr 0x%llx, len %d\n", addr, len);
+		r = -EOPNOTSUPP;
+		goto out;
+	}
+	entry[0] = e->msi.address_lo;
+	entry[1] = e->msi.address_hi;
+	entry[2] = e->msi.data;
+	entry[3] = !!(adev->guest_msix_entries[idx].flags &
+			KVM_ASSIGNED_MSIX_MASK);
+	memcpy(val, &entry[addr % PCI_MSIX_ENTRY_SIZE / 4], len);
+
+out:
+	mutex_unlock(&adev->kvm->lock);
+	return r;
+}
+
+static int msix_mmio_write(struct kvm_io_device *this, gpa_t addr, int len,
+			   const void *val)
+{
+	struct kvm_assigned_dev_kernel *adev =
+			container_of(this, struct kvm_assigned_dev_kernel,
+				     msix_mmio_dev);
+	int idx, r = 0;
+	unsigned long new_val = *(unsigned long *)val;
+	bool entry_masked;
+
+	mutex_lock(&adev->kvm->lock);
+	if (!msix_mmio_in_range(adev, addr, len, &idx)) {
+		r = -EOPNOTSUPP;
+		goto out;
+	}
+	if ((addr & 0x3) || len != 4) {
+		printk(KERN_WARNING
+			"KVM: Unaligned writing for device MSI-X MMIO! "
+			"addr 0x%llx, len %d, val 0x%lx\n",
+			addr, len, new_val);
+		r = -EOPNOTSUPP;
+		goto out;
+	}
+	entry_masked = adev->guest_msix_entries[idx].flags &
+			KVM_ASSIGNED_MSIX_MASK;
+	if (addr % PCI_MSIX_ENTRY_SIZE != PCI_MSIX_ENTRY_VECTOR_CTRL) {
+		/* Only allow entry modification when entry was masked */
+		if (!entry_masked) {
+			printk(KERN_WARNING
+				"KVM: guest try to write unmasked MSI-X entry. "
+				"addr 0x%llx, len %d, val 0x%lx\n",
+				addr, len, new_val);
+			r = 0;
+		} else
+			/* Leave it to QEmu */
+			r = -EOPNOTSUPP;
+		goto out;
+	}
+	if (new_val & ~1ul) {
+		printk(KERN_WARNING
+			"KVM: Bad writing for device MSI-X MMIO! "
+			"addr 0x%llx, len %d, val 0x%lx\n",
+			addr, len, new_val);
+		r = -EOPNOTSUPP;
+		goto out;
+	}
+	if (new_val == 1 && !entry_masked) {
+		adev->guest_msix_entries[idx].flags |=
+			KVM_ASSIGNED_MSIX_MASK;
+		update_msix_mask(adev, idx);
+	} else if (new_val == 0 && entry_masked) {
+		adev->guest_msix_entries[idx].flags &=
+			~KVM_ASSIGNED_MSIX_MASK;
+		update_msix_mask(adev, idx);
+	}
+out:
+	mutex_unlock(&adev->kvm->lock);
+
+	return r;
+}
+
+static const struct kvm_io_device_ops msix_mmio_ops = {
+	.read     = msix_mmio_read,
+	.write    = msix_mmio_write,
+};
+
 #endif
 
 long kvm_vm_ioctl_assigned_device(struct kvm *kvm, unsigned ioctl,
-- 
1.7.0.1