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From:   Vivek Goyal <vgoyal@redhat.com>
To:     linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-nvdimm@lists.01.org, virtio-fs@redhat.com, miklos@szeredi.hu
Cc:     vgoyal@redhat.com, stefanha@redhat.com, dgilbert@redhat.com,
        mst@redhat.com, Sebastien Boeuf <sebastien.boeuf@intel.com>
Subject: [PATCH 05/20] virtio: Implement get_shm_region for MMIO transport
Date:   Wed,  4 Mar 2020 11:58:30 -0500
Message-Id: <20200304165845.3081-6-vgoyal@redhat.com>
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From: Sebastien Boeuf <sebastien.boeuf@intel.com>

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>
---
 drivers/virtio/virtio_mmio.c     | 32 ++++++++++++++++++++++++++++++++
 include/uapi/linux/virtio_mmio.h | 11 +++++++++++
 2 files changed, 43 insertions(+)

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 97d5725fd9a2..4922a1a9e3a7 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -500,6 +500,37 @@ static const char *vm_bus_name(struct virtio_device =
*vdev)
 	return vm_dev->pdev->name;
 }
=20
+static bool vm_get_shm_region(struct virtio_device *vdev,
+			      struct virtio_shm_region *region, u8 id)
+{
+	struct virtio_mmio_device *vm_dev =3D 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 =3D (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_LEN_LOW);
+	len |=3D (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_LEN_HIGH) << 32;
+
+	region->len =3D 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 =3D=3D ~(u64)0) {
+		return false;
+	}
+
+	/* Read the region base address */
+	addr =3D (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_BASE_LOW);
+	addr |=3D (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_BASE_HIGH) << 32;
+
+	region->addr =3D addr;
+
+	return true;
+}
+
 static const struct virtio_config_ops virtio_mmio_config_ops =3D {
 	.get		=3D vm_get,
 	.set		=3D vm_set,
@@ -512,6 +543,7 @@ static const struct virtio_config_ops virtio_mmio_con=
fig_ops =3D {
 	.get_features	=3D vm_get_features,
 	.finalize_features =3D vm_finalize_features,
 	.bus_name	=3D vm_bus_name,
+	.get_shm_region =3D vm_get_shm_region,
 };
=20
=20
diff --git a/include/uapi/linux/virtio_mmio.h b/include/uapi/linux/virtio=
_mmio.h
index c4b09689ab64..0650f91bea6c 100644
--- 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
=20
+/* 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
=20
--=20
2.20.1