Commit 4a22c4ce authored by Johannes Berg's avatar Johannes Berg Committed by Richard Weinberger
Browse files

um: virt-pci: don't do DMA from stack 



When enabling VMAP_STACK, SG helpers immediately complained
that we were doing DMA from stack. Use per-CPU variables to
avoid that.

Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
parent 1568cb0e

arch/um/drivers/virt-pci.c

+78 −26
Original line number Diff line number Diff line
@@ -56,6 +56,13 @@ static unsigned long um_pci_msi_used[BITS_TO_LONGS(MAX_MSI_VECTORS)]; 


#define UM_VIRT_PCI_MAXDELAY 40000



struct um_pci_message_buffer {

	struct virtio_pcidev_msg hdr;

	u8 data[8];

};



static struct um_pci_message_buffer __percpu *um_pci_msg_bufs;



static int um_pci_send_cmd(struct um_pci_device *dev,

			   struct virtio_pcidev_msg *cmd,

			   unsigned int cmd_size,
@@ -68,11 +75,12 @@ static int um_pci_send_cmd(struct um_pci_device *dev, 
		[1] = extra ? &extra_sg : &in_sg,

		[2] = extra ? &in_sg : NULL,

	};

	struct um_pci_message_buffer *buf;

	int delay_count = 0;

	int ret, len;

	bool posted;



	if (WARN_ON(cmd_size < sizeof(*cmd)))

	if (WARN_ON(cmd_size < sizeof(*cmd) || cmd_size > sizeof(*buf)))

		return -EINVAL;



	switch (cmd->op) {
@@ -88,6 +96,9 @@ static int um_pci_send_cmd(struct um_pci_device *dev, 
		break;

	}



	buf = get_cpu_var(um_pci_msg_bufs);

	memcpy(buf, cmd, cmd_size);



	if (posted) {

		u8 *ncmd = kmalloc(cmd_size + extra_size, GFP_ATOMIC);
@@ -102,7 +113,10 @@ static int um_pci_send_cmd(struct um_pci_device *dev, 
		} else {

			/* try without allocating memory */

			posted = false;

			cmd = (void *)buf;

		}

	} else {

		cmd = (void *)buf;

	}



	sg_init_one(&out_sg, cmd, cmd_size);
@@ -118,11 +132,12 @@ static int um_pci_send_cmd(struct um_pci_device *dev, 
				posted ? cmd : HANDLE_NO_FREE(cmd),

				GFP_ATOMIC);

	if (ret)

		return ret;

		goto out;



	if (posted) {

		virtqueue_kick(dev->cmd_vq);

		return 0;

		ret = 0;

		goto out;

	}



	/* kick and poll for getting a response on the queue */
@@ -148,6 +163,8 @@ static int um_pci_send_cmd(struct um_pci_device *dev, 
	}

	clear_bit(UM_PCI_STAT_WAITING, &dev->status);



out:

	put_cpu_var(um_pci_msg_bufs);

	return ret;

}
@@ -161,12 +178,17 @@ static unsigned long um_pci_cfgspace_read(void *priv, unsigned int offset, 
		.size = size,

		.addr = offset,

	};

	/* maximum size - we may only use parts of it */

	u8 data[8];

	/* buf->data is maximum size - we may only use parts of it */

	struct um_pci_message_buffer *buf;

	u8 *data;

	unsigned long ret = ~0ULL;



	if (!dev)

		return ~0ULL;



	buf = get_cpu_var(um_pci_msg_bufs);

	data = buf->data;



	memset(data, 0xff, sizeof(data));



	switch (size) {
@@ -179,27 +201,34 @@ static unsigned long um_pci_cfgspace_read(void *priv, unsigned int offset, 
		break;

	default:

		WARN(1, "invalid config space read size %d\n", size);

		return ~0ULL;

		goto out;

	}



	if (um_pci_send_cmd(dev, &hdr, sizeof(hdr), NULL, 0,

			    data, sizeof(data)))

		return ~0ULL;

	if (um_pci_send_cmd(dev, &hdr, sizeof(hdr), NULL, 0, data, 8))

		goto out;



	switch (size) {

	case 1:

		return data[0];

		ret = data[0];

		break;

	case 2:

		return le16_to_cpup((void *)data);

		ret = le16_to_cpup((void *)data);

		break;

	case 4:

		return le32_to_cpup((void *)data);

		ret = le32_to_cpup((void *)data);

		break;

#ifdef CONFIG_64BIT

	case 8:

		return le64_to_cpup((void *)data);

		ret = le64_to_cpup((void *)data);

		break;

#endif

	default:

		return ~0ULL;

		break;

	}



out:

	put_cpu_var(um_pci_msg_bufs);

	return ret;

}



static void um_pci_cfgspace_write(void *priv, unsigned int offset, int size,
@@ -272,8 +301,13 @@ static void um_pci_bar_copy_from(void *priv, void *buffer, 
static unsigned long um_pci_bar_read(void *priv, unsigned int offset,

				     int size)

{

	/* maximum size - we may only use parts of it */

	u8 data[8];

	/* buf->data is maximum size - we may only use parts of it */

	struct um_pci_message_buffer *buf;

	u8 *data;

	unsigned long ret = ~0ULL;



	buf = get_cpu_var(um_pci_msg_bufs);

	data = buf->data;



	switch (size) {

	case 1:
@@ -285,25 +319,33 @@ static unsigned long um_pci_bar_read(void *priv, unsigned int offset, 
		break;

	default:

		WARN(1, "invalid config space read size %d\n", size);

		return ~0ULL;

		goto out;

	}



	um_pci_bar_copy_from(priv, data, offset, size);



	switch (size) {

	case 1:

		return data[0];

		ret = data[0];

		break;

	case 2:

		return le16_to_cpup((void *)data);

		ret = le16_to_cpup((void *)data);

		break;

	case 4:

		return le32_to_cpup((void *)data);

		ret = le32_to_cpup((void *)data);

		break;

#ifdef CONFIG_64BIT

	case 8:

		return le64_to_cpup((void *)data);

		ret = le64_to_cpup((void *)data);

		break;

#endif

	default:

		return ~0ULL;

		break;

	}



out:

	put_cpu_var(um_pci_msg_bufs);

	return ret;

}



static void um_pci_bar_copy_to(void *priv, unsigned int offset,
@@ -823,10 +865,16 @@ static int um_pci_init(void) 
		 "No virtio device ID configured for PCI - no PCI support\n"))

		return 0;



	bridge = pci_alloc_host_bridge(0);

	if (!bridge)

	um_pci_msg_bufs = alloc_percpu(struct um_pci_message_buffer);

	if (!um_pci_msg_bufs)

		return -ENOMEM;



	bridge = pci_alloc_host_bridge(0);

	if (!bridge) {

		err = -ENOMEM;

		goto free;

	}



	um_pci_fwnode = irq_domain_alloc_named_fwnode("um-pci");

	if (!um_pci_fwnode) {

		err = -ENOMEM;
@@ -878,8 +926,11 @@ static int um_pci_init(void) 
		irq_domain_remove(um_pci_inner_domain);

	if (um_pci_fwnode)

		irq_domain_free_fwnode(um_pci_fwnode);

	if (bridge) {

		pci_free_resource_list(&bridge->windows);

		pci_free_host_bridge(bridge);

	}

	free_percpu(um_pci_msg_bufs);

	return err;

}

module_init(um_pci_init);
@@ -891,5 +942,6 @@ static void um_pci_exit(void) 
	irq_domain_remove(um_pci_inner_domain);

	pci_free_resource_list(&bridge->windows);

	pci_free_host_bridge(bridge);

	free_percpu(um_pci_msg_bufs);

}

module_exit(um_pci_exit);