RE: [Xen-devel] Drivers cannot write to msix_iomem from DomU, is this right?

["Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>]

The MSI-x will include vector information, which should be resource owned by Xen HV.

For example, if domU set the vector to be same as another device that owned by another domain (or dom0), or Xen HV's IPI, then it will cause trouble.

 

--jyh

---

From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Yi, Shunli
Sent: 2009年7月10日 11:57
To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] Drivers cannot write to msix_iomem from DomU, is this right?

Hi:

I’m using the Xen-3.3.1. and I find Xend doesn’t permit the DomU driver to access the msix_iomem.

 

"xend/server/pciif.py" : Line :342.

        if dev.msix:

            for (start, size) in dev.msix_iomem:

                start_pfn = start>>PAGE_SHIFT

                nr_pfns = (size+(PAGE_SIZE-1))>>PAGE_SHIFT

                log.debug('pci-msix: remove permission for 0x%x/0x%x 0x%x/0x%x' % \

                         (start,size, start_pfn, nr_pfns))

                rc = xc.domain_iomem_permission(domid = fe_domid,

                                                first_pfn = start_pfn,

                                                nr_pfns = nr_pfns,

                                                allow_access = False)

 

I haven’t wrote any driver code, but I think the driver should can write messages to the msix_iomem.

Because the driver will write some MSI information to the MSI register.

 

And I find following code in bnx2-1.8.5b:

File :                       bnx2.c  

Version:               1.8.5b

Function:             bnx2_enable_msix()

    bnx2_setup_msix_tbl(bp);

    REG_WR(bp, BNX2_PCI_MSIX_CONTROL, BNX2_MAX_MSIX_HW_VEC - 1);

    REG_WR(bp, BNX2_PCI_MSIX_TBL_OFF_BIR, BNX2_PCI_GRC_WINDOW2_BASE);

REG_WR(bp, BNX2_PCI_MSIX_PBA_OFF_BIT, BNX2_PCI_GRC_WINDOW3_BASE);

 

 

So, I think the msix_iomem should be always  writable for the DomU.

Am I Right?

 

 

Best Regards!

 

SHUNLI YI

WEBSENSE NETWORK SECURITY TECHNOLOGY R&D (BEIJING) CO. LTD.
ph: +8610.5884.4142

 

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