Commit c97eb679 authored by Rusty Russell's avatar Rusty Russell
Browse files

tools/lguest: insert driver references from the 1.0 spec (4.1 Virtio Over PCI) 



As a demonstration, the lguest launcher is pretty strict, trying to
catch badly behaved drivers.  Document this precisely.

A good implementation would *NOT* crash the guest when these happened!

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 8dc425ff

tools/lguest/lguest.c

+57 −2
Original line number Diff line number Diff line
@@ -1211,7 +1211,12 @@ static bool valid_bar_access(struct device *d, 
	    && cfg_access->cap.length != 4)

		return false;



	/* Offset must be multiple of length */

	/*

	 * 4.1.4.7.2:

	 *

	 *  The driver MUST NOT write a cap.offset which is not a multiple of

	 *  cap.length (ie. all accesses MUST be aligned).

	 */

	if (cfg_access->cap.offset % cfg_access->cap.length != 0)

		return false;
@@ -1342,7 +1347,13 @@ static bool pci_data_iowrite(u16 port, u32 mask, u32 val) 
		return true;

	}



	/* Complain about other writes. */

	/*

	 * 4.1.4.1:

	 *

	 *  The driver MUST NOT write into any field of the capability

	 *  structure, with the exception of those with cap_type

	 *  VIRTIO_PCI_CAP_PCI_CFG...

	 */

	return false;

}
@@ -1789,6 +1800,12 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask) 
		restore_vq_config(&d->mmio->cfg, vq);

		goto write_through16;

	case offsetof(struct virtio_pci_mmio, cfg.queue_size):

		/*

		 * 4.1.4.3.2:

		 *

		 *  The driver MUST NOT write a value which is not a power of 2

		 *  to queue_size.

		 */

		if (val & (val-1))

			errx(1, "%s: invalid queue size %u\n", d->name, val);

		if (d->mmio->cfg.queue_enable)
@@ -1799,11 +1816,22 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask) 
		errx(1, "%s: attempt to set MSIX vector to %u",

		     d->name, val);

	case offsetof(struct virtio_pci_mmio, cfg.queue_enable):

		/*

		 * 4.1.4.3.2:

		 *

		 *  The driver MUST NOT write a 0 to queue_enable.

		 */

		if (val != 1)

			errx(1, "%s: setting queue_enable to %u", d->name, val);

		d->mmio->cfg.queue_enable = val;

		save_vq_config(&d->mmio->cfg,

			       vq_by_num(d, d->mmio->cfg.queue_select));

		/*

		 * 4.1.4.3.2:

		 *

		 *  The driver MUST configure the other virtqueue fields before

		 *  enabling the virtqueue with queue_enable.

		 */

		enable_virtqueue(d, vq_by_num(d, d->mmio->cfg.queue_select));

		goto write_through16;

	case offsetof(struct virtio_pci_mmio, cfg.queue_notify_off):
@@ -1814,6 +1842,12 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask) 
	case offsetof(struct virtio_pci_mmio, cfg.queue_avail_hi):

	case offsetof(struct virtio_pci_mmio, cfg.queue_used_lo):

	case offsetof(struct virtio_pci_mmio, cfg.queue_used_hi):

		/*

		 * 4.1.4.3.2:

		 *

		 *  The driver MUST configure the other virtqueue fields before

		 *  enabling the virtqueue with queue_enable.

		 */

		if (d->mmio->cfg.queue_enable)

			errx(1, "%s: changing queue on live device",

			     d->name);
@@ -1837,9 +1871,23 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask) 
		}

		/* Fall through... */

	default:

		/*

		 * 4.1.4.3.2:

		 *

		 *   The driver MUST NOT write to device_feature, num_queues,

		 *   config_generation or queue_notify_off.

		 */

		errx(1, "%s: Unexpected write to offset %u", d->name, off);

	}





	/*

	 * 4.1.3.1:

	 *

	 *  The driver MUST access each field using the “natural” access

	 *  method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for

	 *  16-bit fields and 8-bit accesses for 8-bit fields.

	 */

write_through32:

	if (mask != 0xFFFFFFFF) {

		errx(1, "%s: non-32-bit write to offset %u (%#x)",
@@ -1923,6 +1971,13 @@ static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask) 
			goto read_through8;

	}



	/*

	 * 4.1.3.1:

	 *

	 *  The driver MUST access each field using the “natural” access

	 *  method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for

	 *  16-bit fields and 8-bit accesses for 8-bit fields.

	 */

read_through32:

	if (mask != 0xFFFFFFFF)

		errx(1, "%s: non-32-bit read to offset %u (%#x)",