[RFC PATCH 10/12] virtio/s390: consolidate DMA allocations

Halil Pasic
2019-04-04T23:16:20Z

We can reduce the number of DMA allocations by pulling the bits
of memory that belongs to virtio_ccw_device and needs to be DMA
memory into a single area.

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
---
drivers/s390/virtio/virtio_ccw.c | 48 ++++++++++++++--------------------------
1 file changed, 16 insertions(+), 32 deletions(-)

diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index aa45a6a027ae..7268149f2ee8 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -49,12 +49,12 @@ struct vq_config_block {
struct vcdev_dma_area {
unsigned long indicators;
unsigned long indicators2;
+ struct vq_config_block config_block;
+ __u8 status; /* TODO check __aligned(8); */
};

struct virtio_ccw_device {
struct virtio_device vdev;
- __u8 *status;
- dma_addr_t status_dma_addr;
__u8 config[VIRTIO_CCW_CONFIG_SIZE];
struct ccw_device *cdev;
__u32 curr_io;
@@ -64,8 +64,6 @@ struct virtio_ccw_device {
spinlock_t lock;
struct mutex io_lock; /* Serializes I/O requests */
struct list_head virtqueues;
- struct vq_config_block *config_block;
- dma_addr_t config_block_dma_addr;
bool is_thinint;
bool going_away;
bool device_lost;
@@ -450,15 +448,15 @@ static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev,
{
int ret;

- vcdev->config_block->index = index;
+ vcdev->dma_area->config_block.index = index;
ccw->cmd_code = CCW_CMD_READ_VQ_CONF;
ccw->flags = 0;
ccw->count = sizeof(struct vq_config_block);
- ccw->cda = (__u32)(unsigned long)(vcdev->config_block);
+ ccw->cda = (__u32)(unsigned long)(&vcdev->dma_area->config_block);
ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_VQ_CONF);
if (ret)
return ret;
- return vcdev->config_block->num ?: -ENOENT;
+ return vcdev->dma_area->config_block.num ?: -ENOENT;
}

static void virtio_ccw_del_vq(struct virtqueue *vq, struct ccw1 *ccw)
@@ -754,7 +752,7 @@ static void virtio_ccw_reset(struct virtio_device *vdev)
return;

/* Zero status bits. */
- *vcdev->status = 0;
+ vcdev->dma_area->status = 0;

/* Send a reset ccw on device. */
ccw->cmd_code = CCW_CMD_VDEV_RESET;
@@ -967,11 +965,11 @@ static void virtio_ccw_set_config(struct virtio_device *vdev,
static u8 virtio_ccw_get_status(struct virtio_device *vdev)
{
struct virtio_ccw_device *vcdev = to_vc_device(vdev);
- u8 old_status = *vcdev->status;
+ u8 old_status = vcdev->dma_area->status;
vc_dma_decl_struct(ccw1, ccw);

if (vcdev->revision < 1)
- return *vcdev->status;
+ return vcdev->dma_area->status;

vc_dma_alloc_struct(vdev, ccw);
if (!ccw)
@@ -979,24 +977,24 @@ static u8 virtio_ccw_get_status(struct virtio_device *vdev)

ccw->cmd_code = CCW_CMD_READ_STATUS;
ccw->flags = 0;
- ccw->count = sizeof(*vcdev->status);
- ccw->cda = (__u32)(unsigned long)vcdev->status;
+ ccw->count = sizeof(vcdev->dma_area->status);
+ ccw->cda = (__u32)(unsigned long)&vcdev->dma_area->status;
ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_STATUS);
/*
* If the channel program failed (should only happen if the device
* was hotunplugged, and then we clean up via the machine check
- * handler anyway), vcdev->status was not overwritten and we just
+ * handler anyway), vcdev->dma_area->status was not overwritten and we just
* return the old status, which is fine.
*/
vc_dma_free_struct(vdev, ccw);

- return *vcdev->status;
+ return vcdev->dma_area->status;
}

static void virtio_ccw_set_status(struct virtio_device *vdev, u8 status)
{
struct virtio_ccw_device *vcdev = to_vc_device(vdev);
- u8 old_status = *vcdev->status;
+ u8 old_status = vcdev->dma_area->status;
vc_dma_decl_struct(ccw1, ccw);
int ret;

@@ -1005,15 +1003,15 @@ static void virtio_ccw_set_status(struct virtio_device *vdev, u8 status)
return;

/* Write the status to the host. */
- *vcdev->status = status;
+ vcdev->dma_area->status = status;
ccw->cmd_code = CCW_CMD_WRITE_STATUS;
ccw->flags = 0;
ccw->count = sizeof(status);
- ccw->cda = (__u32)(unsigned long)vcdev->status;
+ ccw->cda = (__u32)(unsigned long)&vcdev->dma_area->status;
ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_STATUS);
/* Write failed? We assume status is unchanged. */
if (ret)
- *vcdev->status = old_status;
+ vcdev->dma_area->status = old_status;
vc_dma_free_struct(vdev, ccw);
}

@@ -1047,8 +1045,6 @@ static void virtio_ccw_release_dev(struct device *_d)
struct virtio_device *dev = dev_to_virtio(_d);
struct virtio_ccw_device *vcdev = to_vc_device(dev);

- vc_dma_free_struct(dev, vcdev->status);
- vc_dma_free_struct(dev, vcdev->config_block);
__vc_dma_free(&vcdev->vdev, PAGE_SIZE, vcdev->dma_area,
vcdev->dma_area_dma_addr);
kfree(vcdev);
@@ -1322,16 +1318,6 @@ static int virtio_ccw_online(struct ccw_device *cdev)
goto out_free;
}

- vc_dma_alloc_struct(&vcdev->vdev, vcdev->config_block);
- if (!vcdev->config_block) {
- ret = -ENOMEM;
- goto out_free;
- }
- vc_dma_alloc_struct(&vcdev->vdev, vcdev->status);
- if (!vcdev->status) {
- ret = -ENOMEM;
- goto out_free;
- }
vcdev->dma_area = __vc_dma_alloc(&vcdev->vdev, PAGE_SIZE,
&vcdev->dma_area_dma_addr);
if (!vcdev->dma_area) {
@@ -1374,8 +1360,6 @@ static int virtio_ccw_online(struct ccw_device *cdev)
return ret;
out_free:
if (vcdev) {
- vc_dma_free_struct(&vcdev->vdev, vcdev->status);
- vc_dma_free_struct(&vcdev->vdev, vcdev->config_block);
__vc_dma_free(&vcdev->vdev, PAGE_SIZE, vcdev->dma_area,
vcdev->dma_area_dma_addr);
}
--
2.16.4