On Tue, 13 Oct 2009, Cinco, Dante wrote:
> I get the above error message when I boot the domU (Linux 2.6.30.1). I'm
> using Xen 3.5-unstable (changeset 20303) with
> pv_ops kernel 2.6.31.1. I use pci-stub to hide the device so that I can
> assign/pass it through to domU. The error is
> coming from ioemu-xxx/hw/pt-msi.c. I think it is complaining about the
> table_off that is part of the mmap() call:
>
> dev->msix->phys_iomem_base = mmap(0, total_entries * 16,
> PROT_WRITE | PROT_READ, MAP_SHARED | MAP_LOCKED,
> fd, dev->msix->table_base + table_off);
>
> When I printed table_off, its value is 0x4100 (not page-aligned) which is
> consistent with the BAR4 offset of the PCI
> device (see below). I think mmap() requires the last argument to be a
> multiple of the page size and results is a map
> error if it is not. Here's the partial output of "lspci -vv -s 0:07:0.1" from
> dom0:
>
> 07:00.0 Fibre Channel: PMC-Sierra Inc. Device 8032 (rev 05)
> Subsystem: Atto Technology Device 003c
> Latency: 0, Cache Line Size: 64 bytes
> Interrupt: pin A routed to IRQ 11
> Capabilities: [60] Message Signalled Interrupts: Mask- 64bit+
> Queue=0/1 Enable+
> Address: 00000000fee11000 Data: 405e
> Capabilities: [70] Express (v2) Endpoint, MSI 01
> DevCap: MaxPayload 4096 bytes, PhantFunc 0, Latency L0s <4us,
> L1 unlimited
> ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
> Capabilities: [b0] MSI-X: Enable- Mask- TabSize=9
> Vector table: BAR=4 offset=00004100
> PBA: BAR=4 offset=00004000
>
> I'm able to workaround this problem by modifying pt-msi.c: force offset to
> zero in mmap() and on the next line, adjust
> the pointer by table_off:
>
> table_off_adjust = table_off & 0x0fff;
> dev->msix->phys_iomem_base = mmap(0, total_entries * 16 +
> table_off_adjust,
> PROT_WRITE | PROT_READ, MAP_SHARED | MAP_LOCKED,
> fd, dev->msix->table_base + table_off -
> table_off_adjust);
> dev->msix->phys_iomem_base = (void *)((char *)dev->msix->phys_iomem_base
> + table_off_adjust);
>
> Ideally, I should only be applying this to my device but since I'm not
> passing any other device that use MSI, I don't see
> any negative effect. In addition, my device only uses MSI and not MSI-X.
>
> Obviously, this is a custom hack but I was wondering if there is a cleaner
> solution for this. Is a non-page aligned BAR
> offset unusual? When I boot Linux 2.6.30.1 on bare metal (no Xen), I don't
> see this error.
I think this workaround is not so bad, you just need to keep
table_off_adjust around because it has to be used in munmap too. _______________________________________________
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