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hw/arm: xenpvh: Reverse virtio-mmio creation order

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We've been creating the virtio-mmio devices in forwards order
but since the qbus lists prepend (rather than append) entries,
the virtio busses end up with decreasing base address order.

Xen enables virtio-mmio nodes in forwards order so there's been
a missmatch. So far, we've been working around this with an
out-of-tree patch to Xen.

This reverses the order making sure the virtio busses end up
ordered with increasing base addresses avoiding the need to
patch Xen.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
This commit is contained in:
Edgar E. Iglesias 2024-08-09 15:39:04 +02:00
parent 0e14c9eb55
commit 692ec9337b
1 changed files with 12 additions and 1 deletions
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13
hw/xen/xen-pvh-common.c
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@ -75,7 +75,18 @@ static void xen_create_virtio_mmio_devices(XenPVHMachineState *s)
{
int i;
for (i = 0; i < s->cfg.virtio_mmio_num; i++) {
/*
* We create the transports in reverse order. Since qbus_realize()
* prepends (not appends) new child buses, the decrementing loop below will
* create a list of virtio-mmio buses with increasing base addresses.
*
* When a -device option is processed from the command line,
* qbus_find_recursive() picks the next free virtio-mmio bus in forwards
* order.
*
* This is what the Xen tools expect.
*/
for (i = s->cfg.virtio_mmio_num - 1; i >= 0; i--) {
hwaddr base = s->cfg.virtio_mmio.base + i * s->cfg.virtio_mmio.size;
qemu_irq irq = qemu_allocate_irq(xen_set_irq, NULL,
s->cfg.virtio_mmio_irq_base + i);