[RFC QEMU PATCH 01/18] virtio: Add shared memory capability

[Huang Rui <ray.huang@xxxxxxx>]

From: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>

Define a new capability type 'VIRTIO_PCI_CAP_SHARED_MEMORY_CFG' to allow
defining shared memory regions with sizes and offsets of 2^32 and more.
Multiple instances of the capability are allowed and distinguished
by a device-specific 'id'.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx>
Signed-off-by: Antonio Caggiano <antonio.caggiano@xxxxxxxxxxxxx>
---
 hw/virtio/virtio-pci.c         | 18 ++++++++++++++++++
 include/hw/virtio/virtio-pci.h |  4 ++++
 2 files changed, 22 insertions(+)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index a1c9dfa7bb..ae4c29cb96 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1191,6 +1191,24 @@ static int virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy,
     return offset;
 }
 
+int virtio_pci_add_shm_cap(VirtIOPCIProxy *proxy,
+                           uint8_t bar, uint64_t offset, uint64_t length,
+                           uint8_t id)
+{
+    struct virtio_pci_cap64 cap = {
+        .cap.cap_len = sizeof cap,
+        .cap.cfg_type = VIRTIO_PCI_CAP_SHARED_MEMORY_CFG,
+    };
+
+    cap.cap.bar = bar;
+    cap.cap.length = cpu_to_le32(length);
+    cap.length_hi = cpu_to_le32(length >> 32);
+    cap.cap.offset = cpu_to_le32(offset);
+    cap.offset_hi = cpu_to_le32(offset >> 32);
+    cap.cap.id = id;
+    return virtio_pci_add_mem_cap(proxy, &cap.cap);
+}
+
 static uint64_t virtio_pci_common_read(void *opaque, hwaddr addr,
                                        unsigned size)
 {
diff --git a/include/hw/virtio/virtio-pci.h b/include/hw/virtio/virtio-pci.h
index 938799e8f6..e67fe422a1 100644
--- a/include/hw/virtio/virtio-pci.h
+++ b/include/hw/virtio/virtio-pci.h
@@ -257,4 +257,8 @@ void virtio_pci_types_register(const 
VirtioPCIDeviceTypeInfo *t);
  */
 unsigned virtio_pci_optimal_num_queues(unsigned fixed_queues);
 
+int virtio_pci_add_shm_cap(VirtIOPCIProxy *proxy,
+                          uint8_t bar, uint64_t offset, uint64_t length,
+                          uint8_t id);
+
 #endif
-- 
2.25.1