Re: Failure to shutdown/reboot with intel_iommu=on

[Lu Baolu <baolu.lu@linux.intel.com>]

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-König 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
> 
>