From: Pekka Enberg <penberg@kernel.org>
Date: Sat, 8 Jan 2011 12:28:59 +0000 (+0200)
Subject: kvm: Implement virtio block device write support
X-Git-Tag: next-20110824~3^2~528^2~18
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=ed7acee4a9de8ad144581de5916e8e6911bf9505;p=karo-tx-linux.git

kvm: Implement virtio block device write support

This patch implement virtio block device write support. The writes are not
persistent because we map the disk image with MAP_PRIVATE.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
---

diff --git a/tools/kvm/blk-virtio.c b/tools/kvm/blk-virtio.c
index 1e26ca5d85bb..13e6d90a66bf 100644
--- a/tools/kvm/blk-virtio.c
+++ b/tools/kvm/blk-virtio.c
@@ -119,10 +119,9 @@ static bool blk_virtio_read(struct kvm *self, struct virt_queue *queue)
 	struct virtio_blk_outhdr *req;
 	struct vring_desc *desc;
 	uint16_t desc_ndx;
-	uint32_t dst_len;
+	uint32_t block_len;
 	uint8_t *status;
-	void *dst;
-	int err;
+	void *block;
 
 	desc_ndx		= queue->vring.avail->ring[queue->last_avail_idx++ % queue->vring.num];
 
@@ -141,8 +140,8 @@ static bool blk_virtio_read(struct kvm *self, struct virt_queue *queue)
 	desc			= &queue->vring.desc[desc->next];
 	assert(!(desc->flags & VRING_DESC_F_INDIRECT));
 
-	dst			= guest_flat_to_host(self, desc->addr);
-	dst_len			= desc->len;
+	block			= guest_flat_to_host(self, desc->addr);
+	block_len		= desc->len;
 
 	/* status */
 	desc			= &queue->vring.desc[desc->next];
@@ -150,16 +149,31 @@ static bool blk_virtio_read(struct kvm *self, struct virt_queue *queue)
 
 	status			= guest_flat_to_host(self, desc->addr);
 
-	if (req->type == VIRTIO_BLK_T_IN) {
-		err = disk_image__read_sector(self->disk_image, req->sector, dst, dst_len);
+	switch (req->type) {
+	case VIRTIO_BLK_T_IN: {
+		int err;
 
+		err		= disk_image__read_sector(self->disk_image, req->sector, block, block_len);
 		if (err)
 			*status			= VIRTIO_BLK_S_IOERR;
 		else
 			*status			= VIRTIO_BLK_S_OK;
-	} else {
+		break;
+	}
+	case VIRTIO_BLK_T_OUT: {
+		int err;
+
+		err		= disk_image__write_sector(self->disk_image, req->sector, block, block_len);
+		if (err)
+			*status			= VIRTIO_BLK_S_IOERR;
+		else
+			*status			= VIRTIO_BLK_S_OK;
+		break;
+	}
+	default:
 		warning("request type %d", req->type);
 		*status			= VIRTIO_BLK_S_IOERR;
+		break;
 	}
 
 	used_elem		= &queue->vring.used->ring[queue->vring.used->idx++ % queue->vring.num];
diff --git a/tools/kvm/disk-image.c b/tools/kvm/disk-image.c
index a6d1e964810a..fd2d96898b82 100644
--- a/tools/kvm/disk-image.c
+++ b/tools/kvm/disk-image.c
@@ -46,7 +46,7 @@ struct disk_image *disk_image__open(const char *filename)
 
 	self->size	= st.st_size;
 
-	self->mmap	= mmap(NULL, self->size, PROT_READ, MAP_PRIVATE, self->fd, 0);
+	self->mmap	= mmap(NULL, self->size, PROT_READ|PROT_WRITE, MAP_PRIVATE, self->fd, 0);
 	if (self->mmap == MAP_FAILED)
 		goto failed_close_fd;
 
@@ -85,3 +85,15 @@ int disk_image__read_sector(struct disk_image *self, uint64_t sector, void *dst,
 
 	return 0;
 }
+
+int disk_image__write_sector(struct disk_image *self, uint64_t sector, void *src, uint32_t src_len)
+{
+	uint64_t offset = sector << SECTOR_SHIFT;
+
+	if (offset + src_len > self->size)
+		return -1;
+
+	memcpy(self->mmap + offset, src, src_len);
+
+	return 0;
+}
diff --git a/tools/kvm/include/kvm/disk-image.h b/tools/kvm/include/kvm/disk-image.h
index 6cba338d4fba..c6413ca51ffa 100644
--- a/tools/kvm/include/kvm/disk-image.h
+++ b/tools/kvm/include/kvm/disk-image.h
@@ -12,5 +12,6 @@ struct disk_image {
 struct disk_image *disk_image__open(const char *filename);
 void disk_image__close(struct disk_image *self);
 int disk_image__read_sector(struct disk_image *self, uint64_t sector, void *dst, uint32_t dst_len);
+int disk_image__write_sector(struct disk_image *self, uint64_t sector, void *src, uint32_t src_len);
 
 #endif /* KVM__DISK_IMAGE_H */