On 22.02.21 09:27, Raimundo Sagarzazu wrote:
>
> Hi all,
>
>
>
> I'm trying to give SMbus access to an inmate cell but the system hangs
> on this error: “Invalid PCI config write, port cfc, size 1, address
> port: 8000f940” when I try to load the cell.
>
>
>
> It’s a x86 host and we already have jailhouse running with two inmate
> cells giving access to net devices, sharing memory, etc.
>
>
>
> From "lspci", I have:
>
>
>
> 00:1f.1 SMBus: Intel Corporation Celeron N3350/Pentium
> N4200/Atom E3900 Series SMBus Controller (rev 0b)
>
> DeviceName: Onboard - Other
>
> Subsystem: Intel Corporation Device 7270
>
> Flags: medium devsel, IRQ 20
>
> Memory at 91616000 (64-bit,
> non-prefetchable) [size=256]
>
> I/O ports at f040 [size=32]
>
> Kernel driver in use: i801_smbus
>
>
>
> From "jailhouse config create ...":
>
>
>
> /* MemRegion: 91516000-915160ff : 0000:00:1f.1 */
>
> {
>
> .phys_start = 0x91516000,
>
> .virt_start = 0x91516000,
>
> .size = 0x1000,
>
> .flags = JAILHOUSE_MEM_READ |
> JAILHOUSE_MEM_WRITE,
>
> },
>
> ...
>
> /* Port I/O: f040-f05f : 0000:00:1f.1 */
>
> PIO_RANGE(0xf040, 0x20),
>
> ...
>
> /* PCIDevice: 00:1f.1 */
>
> {
>
> .type = JAILHOUSE_PCI_TYPE_DEVICE,
>
> .iommu = 1,
>
> .domain = 0x0,
>
> .bdf = 0xf9,
>
> .bar_mask = {
>
> 0xffffff00, 0xffffffff,
> 0x00000000,
>
> 0x00000000, 0xffffffe0,
> 0x00000000,
>
> },
>
> .caps_start = 0,
>
> .num_caps = 0,
>
> .num_msi_vectors = 0,
>
> .msi_64bits = 0,
>
> .msi_maskable = 0,
>
> .num_msix_vectors = 0,
>
> .msix_region_size = 0x0,
>
> .msix_address = 0x0,
>
> },
>
>
>
> First thing I can see is that lspci shows that device's memory region is:
>
> Memory at 91616000 (64-bit, non-prefetchable) [size=256]
>
>
>
> While "jailhouse config create ..." shows:
>
> MemRegion: 91516000-915160ff : 0000:00:1f.1
>
>
>
> Is that correct?
>
>
>
> Anyway, digging in the code I can see that the error comes on
> "hypervisor/pci.c, pci_cfg_write_moderate() ...", when trying to
> access address 0x40 but device has no capabilities.
>
>
>
> Giving access to this device is not a big issue for us because we can
> share "/dev/i2c-0" status over IVshmem but I'd like to known if
> there's something else I can do or it just can't be done.
>
>
>
This config space register might be a side-band register. You could
permit access by modelling it like a capability, ie. create one at 0x04
of the needed size (at least 1 byte) and with write permissions. Cap ID
can be 0 or anything else invalid.
Jan
--
Siemens AG, T RDA IOT
Corporate Competence Center Embedded Linux
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