From: Timothy Pearson <tpearson@raptorengineering.com>
To: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: [BUG] VFIO on POWER9 / QEMU fails to allocate 32-bit DMA
Date: Mon, 3 Aug 2026 17:39:14 -0500 (CDT) [thread overview]
Message-ID: <334689093.41938.1785796754275.JavaMail.zimbra@raptorengineeringinc.com> (raw)
On Linux 6.18, and potentially earlier Linux versions, attempting to pass through any PCI device via VFIO that requires 32-bit DMA results in the following error in the guest VM:
[ 11.705413] cx23885 0000:00:02.0: Warning: IOMMU offset too big for device mask
[ 11.709245] cx23885 0000:00:02.0: mask: 0xffffffff, table offset: 0x800000000000000
The same devices work correctly on the host kernel. It appears that somehow 32-bit DMA is not available within a pSeries guest on a PowerNV host.
next reply other threads:[~2026-08-03 22:45 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-03 22:39 Timothy Pearson [this message]
2026-08-06 5:27 ` [BUG] VFIO on POWER9 / QEMU fails to allocate 32-bit DMA Ritesh Harjani
2026-08-08 5:00 ` Timothy Pearson
2026-08-08 5:09 ` Ritesh Harjani
2026-08-08 5:34 ` Timothy Pearson
2026-08-08 14:13 ` Ritesh Harjani
2026-08-08 16:19 ` Timothy Pearson
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