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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

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