pci-passthrough logging

pci-passthrough logging

[Vikram Ambrose]

Hello,

I'm new to kvm and I'm trying to log pci config and mmio read/writes for 
a particular pci  (pci-e to be precise) device that I've passthrough to 
qemu-kvm (dma=none).

I put a printk into kvm_iodevice_read/write() in linux/virt/kvm/iodev.h 
but the log seems to get corrupted when the action picks up.

I looked at qemu-kvm/hw/pci_host.c and found 
pci_host_data_write/read_mmio[]. But I don't know where those are 
implemented, nor exactly what they do for that matter.

I appologise for the n00b nature of my problem, but there isnt any 
documentation on the pci-passthrough architecture in 
linux/Documentation/kvm or in qemu-kvm.

Does anyone know where/how to log pci-passthrough accesses?

thanks,

Vik.
PS: This is a "one off" question, so I'm not subscribed to the list, 
please make sure my email addresses is in the reply fields.

Re: pci-passthrough logging

[Avi Kivity]

On 02/20/2010 01:58 AM, Vikram Ambrose wrote:
> Hello,
>
> I'm new to kvm and I'm trying to log pci config and mmio read/writes 
> for a particular pci  (pci-e to be precise) device that I've 
> passthrough to qemu-kvm (dma=none).
>
> I put a printk into kvm_iodevice_read/write() in 
> linux/virt/kvm/iodev.h but the log seems to get corrupted when the 
> action picks up.
>
> I looked at qemu-kvm/hw/pci_host.c and found 
> pci_host_data_write/read_mmio[]. But I don't know where those are 
> implemented, nor exactly what they do for that matter.
>
> I appologise for the n00b nature of my problem, but there isnt any 
> documentation on the pci-passthrough architecture in 
> linux/Documentation/kvm or in qemu-kvm.
>
> Does anyone know where/how to log pci-passthrough accesses?

For config-space accesses, hook assigned_dev_pci_{read,write}_config().  
For mmio, hook slow_bar_{read,write}*(), and hack 
assigned_dev_register_regions() to select the slow path (otherwise kvm 
will let the guest write directly to the device).   For pio, hook 
assigned_dev_ioport_{read,write)*().

-- 
error compiling committee.c: too many arguments to function