tree 585f11dc7c338cd8fc042ff546b857dd11a19656
parent 5e9dd8524f7f7960e80125787e16f3ec8f258ddf
author Jean-Philippe Brucker <jean-philippe.brucker@arm.com> 1522864433 +0100
committer Will Deacon <will.deacon@arm.com> 1523010492 +0100

ioeventfd: Don't register on the PIO bus if the arch doesn't support it

virtio/pci.c registers a notification ioeventfd on both PIO and MMIO
buses. But architectures other than x86 cannot differentiate MMIO from
PIO traps, and the kernel always calls kvm_io_bus_read/write with
KVM_MMIO_BUS as argument.

As a result kvmtool's ioeventfd isn't used with virtio PCI, because the
kernel can't find it and all accesses to the doorbell return to
userspace. To fix it, don't set the PIO flag if the architecture doesn't
support it.

Fixes: a508ea95f954 ("virtio/pci: Use port I/O for configuration registers by default")
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>