(switched to email.  Please respond via emailed reply-to-all, not via the
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On Sat, 28 Jan 2012 17:55:38 GMT
bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r@public.gmane.org wrote:

https://bugzilla.kernel.org/show_bug.cgi?id=42679

I don't know if this is a SATA issue or intel-iommu.  Could you guys
please take a look?

           Summary: DMA Read on Marvell 88SE9128 fails when Intel's IOMMU
                    is on
           Product: Memory Management
           Version: 2.5
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Other
        AssignedTo: akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org
        ReportedBy: pawel.zaq-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
        Regression: No


Created an attachment (id=72217)
 --> (https://bugzilla.kernel.org/attachment.cgi?id=72217)
Output of `dmesg' command

I have a MSI Z68A-GD80 B3 motherboard and when I try to enable Intel's IOMMU
(kernel booted with intel_iommu=on), integrated Marvell 88SE9128 SATA
controller doesn't work.

To reproduce:
1. Compile and prepare kernel with Intel IOMMU support enabled
(CONFIG_INTEL_IOMMU=y).
2. Reboot the computer.
3. Enter BIOS and enable VT-d.
4. Boot the kernel with intel_iommu=on parameter.

Right after boot, kernel reports the following errors (SATA controller is at
0b:00.0):

[    2.639774] DRHD: handling fault status reg 3
[    2.639782] DMAR:[DMA Read] Request device [0b:00.1] fault addr fff00000 
[    2.639783] DMAR:[fault reason 02] Present bit in context entry is clear

After a while these entries appear:

[    7.625837] ata14.00: qc timeout (cmd 0xa1)
[    7.628341] ata14.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[    7.935483] ata14: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[   17.908407] ata14.00: qc timeout (cmd 0xa1)
[   17.910935] ata14.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[   17.912276] ata14: limiting SATA link speed to 1.5 Gbps
[   18.219077] ata14: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[   48.134607] ata14.00: qc timeout (cmd 0xa1)
[   48.137508] ata14.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[   48.444646] ata14: SATA link up 1.5 Gbps (SStatus 113 SControl 310)

When there is a disk connected to the controller it does not work. When there
are none, computer starts normally, apart from the huge lag caused by,
presumably, probing the device.

Since this is the secondary controller on these motherboards, to eliminate
those symptoms you can just plug disk in one of available ports of the built-in
Intel SATA controller and disable Marvell's one using BIOS. The other
work-around, if you need to use eSATA capabilities of the latter, is to disable
VT-d techonology also using BIOS.