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tools/lguest: more documentation and checking of virtio 1.0 compliance. 

This is from all the non-PCI parts of the spec.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2015-02-13 17:13:43 +10:30
parent 55c2d7884e
commit d39a6785f4
1 changed files with 293 additions and 14 deletions
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307
tools/lguest/lguest.c
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@ -170,6 +170,9 @@ struct device {
/* Is it operational */
bool running;
/* Has it written FEATURES_OK but not re-checked it? */
bool wrote_features_ok;
/* PCI configuration */
union {
struct pci_config config;
@ -668,7 +671,26 @@ static void trigger_irq(struct virtqueue *vq)
return;
vq->pending_used = 0;
/* If they don't want an interrupt, don't send one... */
/*
* 2.4.7.1:
*
* If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
* The driver MUST set flags to 0 or 1.
*/
if (vq->vring.avail->flags > 1)
errx(1, "%s: avail->flags = %u\n",
vq->dev->name, vq->vring.avail->flags);
/*
* 2.4.7.2:
*
* If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
*
* - The device MUST ignore the used_event value.
* - After the device writes a descriptor index into the used ring:
* - If flags is 1, the device SHOULD NOT send an interrupt.
* - If flags is 0, the device MUST send an interrupt.
*/
if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) {
return;
}
@ -703,6 +725,14 @@ static unsigned wait_for_vq_desc(struct virtqueue *vq,
struct vring_desc *desc;
u16 last_avail = lg_last_avail(vq);
/*
* 2.4.7.1:
*
* The driver MUST handle spurious interrupts from the device.
*
* That's why this is a while loop.
*/
/* There's nothing available? */
while (last_avail == vq->vring.avail->idx) {
u64 event;
@ -776,12 +806,62 @@ static unsigned wait_for_vq_desc(struct virtqueue *vq,
* descriptor chain.
*/
if (desc[i].flags & VRING_DESC_F_INDIRECT) {
/* 2.4.5.3.1:
*
* The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT
* flag unless the VIRTIO_F_INDIRECT_DESC feature was
* negotiated.
*/
if (!(vq->dev->features_accepted &
(1<<VIRTIO_RING_F_INDIRECT_DESC)))
errx(1, "%s: vq indirect not negotiated",
vq->dev->name);
/*
* 2.4.5.3.1:
*
* The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT
* flag within an indirect descriptor (ie. only one
* table per descriptor).
*/
if (desc != vq->vring.desc)
errx(1, "%s: Indirect within indirect",
vq->dev->name);
/*
* Proposed update VIRTIO-134 spells this out:
*
* A driver MUST NOT set both VIRTQ_DESC_F_INDIRECT
* and VIRTQ_DESC_F_NEXT in flags.
*/
if (desc[i].flags & VRING_DESC_F_NEXT)
errx(1, "%s: indirect and next together",
vq->dev->name);
if (desc[i].len % sizeof(struct vring_desc))
errx(1, "Invalid size for indirect buffer table");
/*
* 2.4.5.3.2:
*
* The device MUST ignore the write-only flag
* (flags&VIRTQ_DESC_F_WRITE) in the descriptor that
* refers to an indirect table.
*
* We ignore it here: :)
*/
max = desc[i].len / sizeof(struct vring_desc);
desc = check_pointer(desc[i].addr, desc[i].len);
i = 0;
/* 2.4.5.3.1:
*
* A driver MUST NOT create a descriptor chain longer
* than the Queue Size of the device.
*/
if (max > vq->pci_config.queue_size)
errx(1, "%s: indirect has too many entries",
vq->dev->name);
}
/* Grab the first descriptor, and check it's OK. */
@ -1082,6 +1162,7 @@ static void reset_device(struct device *dev)
}
}
dev->running = false;
dev->wrote_features_ok = false;
/* Now we care if threads die. */
signal(SIGCHLD, (void *)kill_launcher);
@ -1703,6 +1784,18 @@ static void check_virtqueue(struct device *d, struct virtqueue *vq)
|| vq->pci_config.queue_used_hi)
errx(1, "%s: invalid 64-bit queue address", d->name);
/*
* 2.4.1:
*
* The driver MUST ensure that the physical address of the first byte
* of each virtqueue part is a multiple of the specified alignment
* value in the above table.
*/
if (vq->pci_config.queue_desc_lo % 16
|| vq->pci_config.queue_avail_lo % 2
|| vq->pci_config.queue_used_lo % 4)
errx(1, "%s: invalid alignment in queue addresses", d->name);
/* Initialize the virtqueue and check they're all in range. */
vq->vring.num = vq->pci_config.queue_size;
vq->vring.desc = check_pointer(vq->pci_config.queue_desc_lo,
@ -1715,6 +1808,16 @@ static void check_virtqueue(struct device *d, struct virtqueue *vq)
sizeof(*vq->vring.used)
+ (sizeof(vq->vring.used->ring[0])
* vq->vring.num));
/*
* 2.4.9.1:
*
* The driver MUST initialize flags in the used ring to 0
* when allocating the used ring.
*/
if (vq->vring.used->flags != 0)
errx(1, "%s: invalid initial used.flags %#x",
d->name, vq->vring.used->flags);
}
static void start_virtqueue(struct virtqueue *vq)
@ -1768,12 +1871,12 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
d->mmio->cfg.device_feature = (d->features >> 32);
else
d->mmio->cfg.device_feature = 0;
goto write_through32;
goto feature_write_through32;
case offsetof(struct virtio_pci_mmio, cfg.guest_feature_select):
if (val > 1)
errx(1, "%s: Unexpected driver select %u",
d->name, val);
goto write_through32;
goto feature_write_through32;
case offsetof(struct virtio_pci_mmio, cfg.guest_feature):
if (d->mmio->cfg.guest_feature_select == 0) {
d->features_accepted &= ~((u64)0xFFFFFFFF);
@ -1783,11 +1886,19 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
d->features_accepted &= 0xFFFFFFFF;
d->features_accepted |= ((u64)val) << 32;
}
/*
* 2.2.1:
*
* The driver MUST NOT accept a feature which the device did
* not offer
*/
if (d->features_accepted & ~d->features)
errx(1, "%s: over-accepted features %#llx of %#llx",
d->name, d->features_accepted, d->features);
goto write_through32;
case offsetof(struct virtio_pci_mmio, cfg.device_status):
goto feature_write_through32;
case offsetof(struct virtio_pci_mmio, cfg.device_status): {
u8 prev;
verbose("%s: device status -> %#x\n", d->name, val);
/*
* 4.1.4.3.1:
@ -1795,8 +1906,15 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
* The device MUST reset when 0 is written to device_status,
* and present a 0 in device_status once that is done.
*/
if (val == 0)
if (val == 0) {
reset_device(d);
goto write_through8;
}
/* 2.1.1: The driver MUST NOT clear a device status bit. */
if (d->mmio->cfg.device_status & ~val)
errx(1, "%s: unset of device status bit %#x -> %#x",
d->name, d->mmio->cfg.device_status, val);
/*
* 2.1.2:
@ -1808,7 +1926,67 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
&& !(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK))
start_virtqueues(d);
/*
* 3.1.1:
*
* The driver MUST follow this sequence to initialize a device:
* - Reset the device.
* - Set the ACKNOWLEDGE status bit: the guest OS has
* notice the device.
* - Set the DRIVER status bit: the guest OS knows how
* to drive the device.
* - Read device feature bits, and write the subset
* of feature bits understood by the OS and driver
* to the device. During this step the driver MAY
* read (but MUST NOT write) the device-specific
* configuration fields to check that it can
* support the device before accepting it.
* - Set the FEATURES_OK status bit. The driver
* MUST not accept new feature bits after this
* step.
* - Re-read device status to ensure the FEATURES_OK
* bit is still set: otherwise, the device does
* not support our subset of features and the
* device is unusable.
* - Perform device-specific setup, including
* discovery of virtqueues for the device,
* optional per-bus setup, reading and possibly
* writing the device’s virtio configuration
* space, and population of virtqueues.
* - Set the DRIVER_OK status bit. At this point the
* device is “live”.
*/
prev = 0;
switch (val & ~d->mmio->cfg.device_status) {
case VIRTIO_CONFIG_S_DRIVER_OK:
prev |= VIRTIO_CONFIG_S_FEATURES_OK; /* fall thru */
case VIRTIO_CONFIG_S_FEATURES_OK:
prev |= VIRTIO_CONFIG_S_DRIVER; /* fall thru */
case VIRTIO_CONFIG_S_DRIVER:
prev |= VIRTIO_CONFIG_S_ACKNOWLEDGE; /* fall thru */
case VIRTIO_CONFIG_S_ACKNOWLEDGE:
break;
default:
errx(1, "%s: unknown device status bit %#x -> %#x",
d->name, d->mmio->cfg.device_status, val);
}
if (d->mmio->cfg.device_status != prev)
errx(1, "%s: unexpected status transition %#x -> %#x",
d->name, d->mmio->cfg.device_status, val);
/* If they just wrote FEATURES_OK, we make sure they read */
switch (val & ~d->mmio->cfg.device_status) {
case VIRTIO_CONFIG_S_FEATURES_OK:
d->wrote_features_ok = true;
break;
case VIRTIO_CONFIG_S_DRIVER_OK:
if (d->wrote_features_ok)
errx(1, "%s: did not re-read FEATURES_OK",
d->name);
break;
}
goto write_through8;
}
case offsetof(struct virtio_pci_mmio, cfg.queue_select):
vq = vq_by_num(d, val);
/*
@ -1844,7 +2022,9 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
case offsetof(struct virtio_pci_mmio, cfg.queue_msix_vector):
errx(1, "%s: attempt to set MSIX vector to %u",
d->name, val);
case offsetof(struct virtio_pci_mmio, cfg.queue_enable):
case offsetof(struct virtio_pci_mmio, cfg.queue_enable): {
struct virtqueue *vq = vq_by_num(d, d->mmio->cfg.queue_select);
/*
* 4.1.4.3.2:
*
@ -1852,17 +2032,27 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
*/
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:
* 3.1.1:
*
* The driver MUST configure the other virtqueue fields before
* enabling the virtqueue with queue_enable.
* 7. Perform device-specific setup, including discovery of
* virtqueues for the device, optional per-bus setup,
* reading and possibly writing the device’s virtio
* configuration space, and population of virtqueues.
* 8. Set the DRIVER_OK status bit.
*
* All our devices require all virtqueues to be enabled, so
* they should have done that before setting DRIVER_OK.
*/
check_virtqueue(d, vq_by_num(d, d->mmio->cfg.queue_select));
if (d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK)
errx(1, "%s: enabling vs after DRIVER_OK", d->name);
d->mmio->cfg.queue_enable = val;
save_vq_config(&d->mmio->cfg, vq);
check_virtqueue(d, vq);
goto write_through16;
}
case offsetof(struct virtio_pci_mmio, cfg.queue_notify_off):
errx(1, "%s: attempt to write to queue_notify_off", d->name);
case offsetof(struct virtio_pci_mmio, cfg.queue_desc_lo):
@ -1880,6 +2070,26 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
if (d->mmio->cfg.queue_enable)
errx(1, "%s: changing queue on live device",
d->name);
/*
* 3.1.1:
*
* The driver MUST follow this sequence to initialize a device:
*...
* 5. Set the FEATURES_OK status bit. The driver MUST not
* accept new feature bits after this step.
*/
if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_FEATURES_OK))
errx(1, "%s: enabling vs before FEATURES_OK", d->name);
/*
* 6. Re-read device status to ensure the FEATURES_OK bit is
* still set...
*/
if (d->wrote_features_ok)
errx(1, "%s: didn't re-read FEATURES_OK before setup",
d->name);
goto write_through32;
case offsetof(struct virtio_pci_mmio, notify):
vq = vq_by_num(d, val);
@ -1909,6 +2119,27 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
errx(1, "%s: Unexpected write to offset %u", d->name, off);
}
feature_write_through32:
/*
* 3.1.1:
*
* The driver MUST follow this sequence to initialize a device:
*...
* - Set the DRIVER status bit: the guest OS knows how
* to drive the device.
* - Read device feature bits, and write the subset
* of feature bits understood by the OS and driver
* to the device.
*...
* - Set the FEATURES_OK status bit. The driver MUST not
* accept new feature bits after this step.
*/
if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
errx(1, "%s: feature write before VIRTIO_CONFIG_S_DRIVER",
d->name);
if (d->mmio->cfg.device_status & VIRTIO_CONFIG_S_FEATURES_OK)
errx(1, "%s: feature write after VIRTIO_CONFIG_S_FEATURES_OK",
d->name);
/*
* 4.1.3.1:
@ -1951,12 +2182,29 @@ static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask)
case offsetof(struct virtio_pci_mmio, cfg.device_feature):
case offsetof(struct virtio_pci_mmio, cfg.guest_feature_select):
case offsetof(struct virtio_pci_mmio, cfg.guest_feature):
/*
* 3.1.1:
*
* The driver MUST follow this sequence to initialize a device:
*...
* - Set the DRIVER status bit: the guest OS knows how
* to drive the device.
* - Read device feature bits, and write the subset
* of feature bits understood by the OS and driver
* to the device.
*/
if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
errx(1, "%s: feature read before VIRTIO_CONFIG_S_DRIVER",
d->name);
goto read_through32;
case offsetof(struct virtio_pci_mmio, cfg.msix_config):
errx(1, "%s: read of msix_config", d->name);
case offsetof(struct virtio_pci_mmio, cfg.num_queues):
goto read_through16;
case offsetof(struct virtio_pci_mmio, cfg.device_status):
/* As they did read, any write of FEATURES_OK is now fine. */
d->wrote_features_ok = false;
goto read_through8;
case offsetof(struct virtio_pci_mmio, cfg.config_generation):
/*
* 4.1.4.3.1:
@ -1971,6 +2219,15 @@ static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask)
*/
goto read_through8;
case offsetof(struct virtio_pci_mmio, notify):
/*
* 3.1.1:
*
* The driver MUST NOT notify the device before setting
* DRIVER_OK.
*/
if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK))
errx(1, "%s: notify before VIRTIO_CONFIG_S_DRIVER_OK",
d->name);
goto read_through16;
case offsetof(struct virtio_pci_mmio, isr):
if (mask != 0xFF)
@ -1992,6 +2249,23 @@ static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask)
if (off > d->mmio_size - 4)
errx(1, "%s: read past end (%#x)",
d->name, getreg(eip));
/*
* 3.1.1:
* The driver MUST follow this sequence to initialize a device:
*...
* 3. Set the DRIVER status bit: the guest OS knows how to
* drive the device.
* 4. Read device feature bits, and write the subset of
* feature bits understood by the OS and driver to the
* device. During this step the driver MAY read (but MUST NOT
* write) the device-specific configuration fields to check
* that it can support the device before accepting it.
*/
if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
errx(1, "%s: config read before VIRTIO_CONFIG_S_DRIVER",
d->name);
if (mask == 0xFFFFFFFF)
goto read_through32;
else if (mask == 0xFFFF)
@ -2200,6 +2474,10 @@ static void init_pci_config(struct pci_config *pci, u16 type,
*
* The device MUST either present notify_off_multiplier as an even
* power of 2, or present notify_off_multiplier as 0.
*
* 2.1.2:
*
* The device MUST initialize device status to 0 upon reset.
*/
memset(pci, 0, sizeof(*pci));
@ -2340,6 +2618,7 @@ static struct device *new_pci_device(const char *name, u16 type,
dev->name = name;
dev->vq = NULL;
dev->running = false;
dev->wrote_features_ok = false;
dev->mmio_size = sizeof(struct virtio_pci_mmio);
dev->mmio = calloc(1, dev->mmio_size);
dev->features = (u64)1 << VIRTIO_F_VERSION_1;