Hi,
I'm trying to use ioeventfd/irqfds for my shared memory patch. I
followed the usage in the vhost-net patches to see how it's setup for
virtio-pci and tried to follow it as closely as I could. Despite the
call to kvm_vm_ioctl() returning 0, any writes to the assigned 4-byte
memory area do not seem to trigger a write to the corresponding fd.
At this point, I'm just trying to get the ioeventfd happening.
I notice that virtio-pci allocates it's BAR as
PCI_BASE_ADDRESS_SPACE_IO and then uses register_ioport_{read,write}
whereas I use cpu_register_io_memory and the
PCI_BASE_ADDRESS_SPACE_MEMORY type as shown below.
+static void ivshmem_mmio_map(PCIDevice *pci_dev, int region_num,
+ pcibus_t addr, pcibus_t size, int type)
+{
+ PCI_IVShmemState *d = (PCI_IVShmemState *)pci_dev;
+ IVShmemState *s = &d->ivshmem_state;
+
+ s->otheraddr = addr /* this address will be used for the ioeventfd*/
+ cpu_register_physical_memory(addr + 0, 0x100, s->ivshmem_mmio_io_addr);
+}
+ s->ivshmem_mmio_io_addr = cpu_register_io_memory(ivshmem_mmio_read,
+ ivshmem_mmio_write, s);
+ /* region for registers*/
+ pci_register_bar(&d->dev, 0, 0x100,
+ PCI_BASE_ADDRESS_SPACE_MEMORY, ivshmem_mmio_map);
my basic attempt looks like this:
struct kvm_ioeventfd ked;
ked.addr = s->otheraddr + Doorbell;
ked.len = 4;
ked.flags = KVM_IOEVENTFD_FLAG_PIO;
ked.fd = an_eventfd;
ret = kvm_vm_ioctl(kvm_state, KVM_IOEVENTFD, &ked);
but when the guest writes to the offset of Doorbell, I cannot see any
action (via a select on the fd). Is there something obviously wrong
that I'm doing?
When I get this working, I'd be happy to write up a page for the KVM site.
Thanks,
Cam
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