virtio: Implement get_shm_region for MMIO transport

On MMIO a new set of registers is defined for finding SHM
regions.  Add their definitions and use them to find the region.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Cc: kvm@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 627ac04874940323f7260d4811c02f53677668c9..238383ff1064c946878c9577b38c0911def6baf9 100644 (file)
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -498,6 +498,36 @@ static const char *vm_bus_name(struct virtio_device *vdev)
        return vm_dev->pdev->name;
 }
 
+static bool vm_get_shm_region(struct virtio_device *vdev,
+                             struct virtio_shm_region *region, u8 id)
+{
+       struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+       u64 len, addr;
+
+       /* Select the region we're interested in */
+       writel(id, vm_dev->base + VIRTIO_MMIO_SHM_SEL);
+
+       /* Read the region size */
+       len = (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_LEN_LOW);
+       len |= (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_LEN_HIGH) << 32;
+
+       region->len = len;
+
+       /* Check if region length is -1. If that's the case, the shared memory
+        * region does not exist and there is no need to proceed further.
+        */
+       if (len == ~(u64)0)
+               return false;
+
+       /* Read the region base address */
+       addr = (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_BASE_LOW);
+       addr |= (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_BASE_HIGH) << 32;
+
+       region->addr = addr;
+
+       return true;
+}
+
 static const struct virtio_config_ops virtio_mmio_config_ops = {
        .get            = vm_get,
        .set            = vm_set,
@@ -510,6 +540,7 @@ static const struct virtio_config_ops virtio_mmio_config_ops = {
        .get_features   = vm_get_features,
        .finalize_features = vm_finalize_features,
        .bus_name       = vm_bus_name,
+       .get_shm_region = vm_get_shm_region,
 };
 
 

diff --git a/include/uapi/linux/virtio_mmio.h b/include/uapi/linux/virtio_mmio.h
index c4b09689ab644719d1aa28fdb9510dfe9c5a8b5b..0650f91bea6c70f935764070d825d181a2379afb 100644 (file)
--- a/include/uapi/linux/virtio_mmio.h
+++ b/include/uapi/linux/virtio_mmio.h
@@ -122,6 +122,17 @@
 #define VIRTIO_MMIO_QUEUE_USED_LOW     0x0a0
 #define VIRTIO_MMIO_QUEUE_USED_HIGH    0x0a4
 
+/* Shared memory region id */
+#define VIRTIO_MMIO_SHM_SEL             0x0ac
+
+/* Shared memory region length, 64 bits in two halves */
+#define VIRTIO_MMIO_SHM_LEN_LOW         0x0b0
+#define VIRTIO_MMIO_SHM_LEN_HIGH        0x0b4
+
+/* Shared memory region base address, 64 bits in two halves */
+#define VIRTIO_MMIO_SHM_BASE_LOW        0x0b8
+#define VIRTIO_MMIO_SHM_BASE_HIGH       0x0bc
+
 /* Configuration atomicity value */
 #define VIRTIO_MMIO_CONFIG_GENERATION  0x0fc