Re: Failure to shutdown/reboot with intel_iommu=on

[Lu Baolu]

Hi Uwe,

Have you tried commenting out intel_disable_iommus() in
intel_iommu_shutdowan()?

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 0182cff2c7ac..532e62600f95 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4928,8 +4928,10 @@ void intel_iommu_shutdown(void)
        for_each_iommu(iommu, drhd)
                iommu_disable_protect_mem_regions(iommu);

+#if 0
        /* Make sure the IOMMUs are switched off */
        intel_disable_iommus();
+#endif

        up_write(&dmar_global_lock);
 }

Best regards,
baolu

On 5/8/20 11:07 PM, Joerg Roedel wrote:
> + Baolu, Maintainer of Intel IOMMU
>
> Baolu, does that ring any bells?
>
> On Wed, May 06, 2020 at 04:46:02PM +0200, Uwe Kleine-KÃnig wrote:
> > Hello,
> >
> > On my Lenovo T460p I cannot shutdown and reboot when the iommu is
> > enabled. This is using linux 5.2.7 as provided by Debian, 5.6.4 has the
> > same problem. Suspend/resume also fails; I suspect this is the same
> > issue.
> >
> > When requesting power off the kernel messages just end with:
> >
> > 	sd 0:0:0:0: [sda] Synchronizing SCSI cache
> > 	sd 0:0:0:0: [sda] Stopping disk
> > 	e1000e: EEE TX LPI TIMER: 00000011
> > 	ACPI: Preparing to enter system sleep state S5
> > 	reboot: Power down
> > 	acpi_power_off called
> >
> > (photo at https://www.kleine-koenig.org/tmp/uklsiommu.jpg in case I
> > mistyped something. Full dmesg and lspci -vvv at
> > https://www.kleine-koenig.org/tmp/uklsiommu.tar.gz with and without
> > iommu enabled.)
> >
> > With the iommu disabled (CONFIG_INTEL_IOMMU_DEFAULT_ON unset or
> > intel_iommu=off on cmdline) the machine just works as expected
> > (including working suspend/resume).
> >
> > I already talked to tglx on irc but unfortunately no new insights
> > resulted from that.
> >
> > Any ideas how to fix or continue debugging the issue?
> >
> > Best regards
> > Uwe