X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=drivers%2Flguest%2Flguest_device.c;h=8080249957afb6d747631674d32cdc287319f96c;hb=28a4acb48586dc21d2d14a75a7aab7be78b7c83b;hp=84f85e23cca7a65a86b3ffa3647953373c5339b3;hpb=70ec75c5b8e0bda7a16fb387f91e08545f379a0e;p=linux-2.6

diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 84f85e23cc..8080249957 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -1,10 +1,10 @@
 /*P:050 Lguest guests use a very simple method to describe devices.  It's a
- * series of device descriptors contained just above the top of normal
+ * series of device descriptors contained just above the top of normal Guest
  * memory.
  *
  * We use the standard "virtio" device infrastructure, which provides us with a
  * console, a network and a block driver.  Each one expects some configuration
- * information and a "virtqueue" mechanism to send and receive data. :*/
+ * information and a "virtqueue" or two to send and receive data. :*/
 #include <linux/init.h>
 #include <linux/bootmem.h>
 #include <linux/lguest_launcher.h>
@@ -47,13 +47,13 @@ struct lguest_device {
 /* Since the virtio infrastructure hands us a pointer to the virtio_device all
  * the time, it helps to have a curt macro to get a pointer to the struct
  * lguest_device it's enclosed in.  */
-#define to_lgdev(vdev) container_of(vdev, struct lguest_device, vdev)
+#define to_lgdev(vd) container_of(vd, struct lguest_device, vdev)
 
 /*D:130
  * Device configurations
  *
  * The configuration information for a device consists of one or more
- * virtqueues, a feature bitmaks, and some configuration bytes.  The
+ * virtqueues, a feature bitmap, and some configuration bytes.  The
  * configuration bytes don't really matter to us: the Launcher sets them up, and
  * the driver will look at them during setup.
  *
@@ -85,27 +85,34 @@ static unsigned desc_size(const struct lguest_device_desc *desc)
 		+ desc->config_len;
 }
 
-/* This tests (and acknowleges) a feature bit. */
-static bool lg_feature(struct virtio_device *vdev, unsigned fbit)
+/* This gets the device's feature bits. */
+static u32 lg_get_features(struct virtio_device *vdev)
 {
+	unsigned int i;
+	u32 features = 0;
 	struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
-	u8 *features;
-
-	/* Obviously if they ask for a feature off the end of our feature
-	 * bitmap, it's not set. */
-	if (fbit / 8 > desc->feature_len)
-		return false;
-
-	/* The feature bitmap comes after the virtqueues. */
-	features = lg_features(desc);
-	if (!(features[fbit / 8] & (1 << (fbit % 8))))
-		return false;
-
-	/* We set the matching bit in the other half of the bitmap to tell the
-	 * Host we want to use this feature.  We don't use this yet, but we
-	 * could in future. */
-	features[desc->feature_len + fbit / 8] |= (1 << (fbit % 8));
-	return true;
+	u8 *in_features = lg_features(desc);
+
+	/* We do this the slow but generic way. */
+	for (i = 0; i < min(desc->feature_len * 8, 32); i++)
+		if (in_features[i / 8] & (1 << (i % 8)))
+			features |= (1 << i);
+
+	return features;
+}
+
+static void lg_set_features(struct virtio_device *vdev, u32 features)
+{
+	unsigned int i;
+	struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
+	/* Second half of bitmap is features we accept. */
+	u8 *out_features = lg_features(desc) + desc->feature_len;
+
+	memset(out_features, 0, desc->feature_len);
+	for (i = 0; i < min(desc->feature_len * 8, 32); i++) {
+		if (features & (1 << i))
+			out_features[i / 8] |= (1 << (i % 8));
+	}
 }
 
 /* Once they've found a field, getting a copy of it is easy. */
@@ -137,20 +144,26 @@ static u8 lg_get_status(struct virtio_device *vdev)
 	return to_lgdev(vdev)->desc->status;
 }
 
+/* To notify on status updates, we (ab)use the NOTIFY hypercall, with the
+ * descriptor address of the device.  A zero status means "reset". */
+static void set_status(struct virtio_device *vdev, u8 status)
+{
+	unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
+
+	/* We set the status. */
+	to_lgdev(vdev)->desc->status = status;
+	hcall(LHCALL_NOTIFY, (max_pfn<<PAGE_SHIFT) + offset, 0, 0);
+}
+
 static void lg_set_status(struct virtio_device *vdev, u8 status)
 {
 	BUG_ON(!status);
-	to_lgdev(vdev)->desc->status = status;
+	set_status(vdev, status);
 }
 
-/* To reset the device, we (ab)use the NOTIFY hypercall, with the descriptor
- * address of the device.  The Host will zero the status and all the
- * features. */
 static void lg_reset(struct virtio_device *vdev)
 {
-	unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
-
-	hcall(LHCALL_NOTIFY, (max_pfn<<PAGE_SHIFT) + offset, 0, 0);
+	set_status(vdev, 0);
 }
 
 /*
@@ -179,7 +192,7 @@ struct lguest_vq_info
 };
 
 /* When the virtio_ring code wants to prod the Host, it calls us here and we
- * make a hypercall.  We hand the page number of the virtqueue so the Host
+ * make a hypercall.  We hand the physical address of the virtqueue so the Host
  * knows which virtqueue we're talking about. */
 static void lg_notify(struct virtqueue *vq)
 {
@@ -199,7 +212,8 @@ static void lg_notify(struct virtqueue *vq)
  * allocate its own pages and tell the Host where they are, but for lguest it's
  * simpler for the Host to simply tell us where the pages are.
  *
- * So we provide devices with a "find virtqueue and set it up" function. */
+ * So we provide drivers with a "find the Nth virtqueue and set it up"
+ * function. */
 static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
 				    unsigned index,
 				    void (*callback)(struct virtqueue *vq))
@@ -285,7 +299,8 @@ static void lg_del_vq(struct virtqueue *vq)
 
 /* The ops structure which hooks everything together. */
 static struct virtio_config_ops lguest_config_ops = {
-	.feature = lg_feature,
+	.get_features = lg_get_features,
+	.set_features = lg_set_features,
 	.get = lg_get,
 	.set = lg_set,
 	.get_status = lg_get_status,