Commit 704a0b5f authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Rusty Russell
Browse files

virtio_mmio: fix access width for mmio 



Going over the virtio mmio code, I noticed that it doesn't correctly
access modern device config values using "natural" accessors: it uses
readb to get/set them byte by byte, while the virtio 1.0 spec explicitly states:

	4.2.2.2 Driver Requirements: MMIO Device Register Layout

	...

	The driver MUST only use 32 bit wide and aligned reads and writes to
	access the control registers described in table 4.1.
	For the device-specific configuration space, the driver MUST use
	8 bit wide accesses for 8 bit wide fields, 16 bit wide and aligned
	accesses for 16 bit wide fields and 32 bit wide and aligned accesses for
	32 and 64 bit wide fields.

Borrow code from virtio_pci_modern to do this correctly.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent a4994b81

drivers/virtio/virtio_mmio.c

+71 −8
Original line number Diff line number Diff line
@@ -156,22 +156,85 @@ static void vm_get(struct virtio_device *vdev, unsigned offset, 
		   void *buf, unsigned len)

{

	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);

	void __iomem *base = vm_dev->base + VIRTIO_MMIO_CONFIG;

	u8 b;

	__le16 w;

	__le32 l;



	if (vm_dev->version == 1) {

		u8 *ptr = buf;

		int i;



		for (i = 0; i < len; i++)

		ptr[i] = readb(vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);

			ptr[i] = readb(base + offset + i);

		return;

	}



	switch (len) {

	case 1:

		b = readb(base + offset);

		memcpy(buf, &b, sizeof b);

		break;

	case 2:

		w = cpu_to_le16(readw(base + offset));

		memcpy(buf, &w, sizeof w);

		break;

	case 4:

		l = cpu_to_le32(readl(base + offset));

		memcpy(buf, &l, sizeof l);

		break;

	case 8:

		l = cpu_to_le32(readl(base + offset));

		memcpy(buf, &l, sizeof l);

		l = cpu_to_le32(ioread32(base + offset + sizeof l));

		memcpy(buf + sizeof l, &l, sizeof l);

		break;

	default:

		BUG();

	}

}



static void vm_set(struct virtio_device *vdev, unsigned offset,

		   const void *buf, unsigned len)

{

	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);

	void __iomem *base = vm_dev->base + VIRTIO_MMIO_CONFIG;

	u8 b;

	__le16 w;

	__le32 l;



	if (vm_dev->version == 1) {

		const u8 *ptr = buf;

		int i;



		for (i = 0; i < len; i++)

		writeb(ptr[i], vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);

			writeb(ptr[i], base + offset + i);



		return;

	}



	switch (len) {

	case 1:

		memcpy(&b, buf, sizeof b);

		writeb(b, base + offset);

		break;

	case 2:

		memcpy(&w, buf, sizeof w);

		writew(le16_to_cpu(w), base + offset);

		break;

	case 4:

		memcpy(&l, buf, sizeof l);

		writel(le32_to_cpu(l), base + offset);

		break;

	case 8:

		memcpy(&l, buf, sizeof l);

		writel(le32_to_cpu(l), base + offset);

		memcpy(&l, buf + sizeof l, sizeof l);

		writel(le32_to_cpu(l), base + offset + sizeof l);

		break;

	default:

		BUG();

	}

}



static u32 vm_generation(struct virtio_device *vdev)

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