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xen-devel
Re: [Xen-devel] Re: Accessing PCI BAR space directly from XEN hypervisor
On 14/06/2011 04:25, "veerasena reddy" <veeruyours@xxxxxxxxx> wrote:
> Hi,
>
> Can someone please throw some light on this
>
> Thanks in advance.
You'll have to set up a fixmap slot and use set_fixmap and fix_to_virt. Xen
doesn't have ioremap.
-- Keir
> Regards,
> VSR.
> On Mon, Jun 13, 2011 at 2:24 PM, veerasena reddy <veeruyours@xxxxxxxxx> wrote:
>> Hi,
>>
>> I am doing an experiment to see if I can get more throughput by moving the Tx
>> ring update and doorbell ring mechanism to hypervisor and provide a hypercall
>> to HVM Guest. When there is a Tx packet ready, the HVM guest invokes the
>> hypercall along with the packet address as argument. The hypercall function
>> will write the packet address to the Tx ring and rings the doorbell directly
>> without involving dom0.
>>
>> AS part of this, i need to access IO Memory BAR region of the PCI network
>> device from XEN hypervisor (hypercall handler). For this, i tried converting
>> the BAR Physical address (captured from lspci as shown below) of the PCI
>> device to MFN, but got all F's (invalid entry). Even pfn_valid(0xf0904000)
>> failed on this address. Where as I could successfully map a dom0 page
>> (allocated using vmalloc()) and access in hypervisor using
>> map_domain_page(mfn).
>>
>> Could any one please suggest how to access the BAR regions of a PCI device
>> from hypervisor? how to do mapping and read/write operations?
>>
>> Also, Could you please explain the difference between mapping locally
>> allocated pages and PCI BAR memory of dom0 in hypervisor?
>>
>> Thanks in advance.
>>
>> Regards,
>> VSR.
>> ==========================
>> [root@fc13 xen]# lspci -vvs 09:00.0
>> 09:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B
>> PCI Express Gigabit Ethernet controller (rev 03)
>> Subsystem: Lenovo Device 2131
>> Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
>> Stepping- SERR+ FastB2B- DisINTx+
>> Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort-
>> <MAbort- >SERR- <PERR- INTx-
>> Latency: 0, Cache Line Size: 64 bytes
>> Interrupt: pin A routed to IRQ 1247
>> Region 0: I/O ports at 4000 [size=256]
>> Region 2: Memory at f0904000 (64-bit, prefetchable) [size=4K]
>> Region 4: Memory at f0900000 (64-bit, prefetchable) [size=16K]
>> [virtual] Expansion ROM at f0920000 [disabled] [size=128K]
>> ===========================
>
>
>
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> Xen-devel@xxxxxxxxxxxxxxxxxxx
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