* Re: Kdump kernel hang when set amd_iommu=off [not found] ` <20180126080622.GC1759-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org> @ 2018-02-13 13:25 ` Joerg Roedel [not found] ` <20180213132520.nqn5osmgsubzjzcq-zLv9SwRftAIdnm+yROfE0A@public.gmane.org> 0 siblings, 1 reply; 2+ messages in thread From: Joerg Roedel @ 2018-02-13 13:25 UTC (permalink / raw) To: Baoquan He; +Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA Hi Baoquan, On Fri, Jan 26, 2018 at 04:06:22PM +0800, Baoquan He wrote: > Saw Huawei's bug report about kdump kernel hang when intel_iommu=off > is set. I met the similar problem in amd system, only set amd_iommu=off > in kdump kernel, it means amd_iommu is on in 1st kernel. > > I am reading doc and code, trying to debug. Please help have a look when > convenient, see if there's hint or direction. Yeah, I know that this is broken on the AMD-IOMMU side. Problem is that the IOMMU hardware needs to be disabled in the kdump kernel when amd_iommu=off is on the command-line. I'll look into fixing that. I thought we fixed this a while ago already for VT-d, is it broken again? Joerg ^ permalink raw reply [flat|nested] 2+ messages in thread
[parent not found: <20180213132520.nqn5osmgsubzjzcq-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>]
* Re: Kdump kernel hang when set amd_iommu=off [not found] ` <20180213132520.nqn5osmgsubzjzcq-zLv9SwRftAIdnm+yROfE0A@public.gmane.org> @ 2018-02-14 10:07 ` Baoquan He 0 siblings, 0 replies; 2+ messages in thread From: Baoquan He @ 2018-02-14 10:07 UTC (permalink / raw) To: Joerg Roedel; +Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA Hi Joerg, On 02/13/18 at 02:25pm, Joerg Roedel wrote: > Hi Baoquan, > > On Fri, Jan 26, 2018 at 04:06:22PM +0800, Baoquan He wrote: > > Saw Huawei's bug report about kdump kernel hang when intel_iommu=off > > is set. I met the similar problem in amd system, only set amd_iommu=off > > in kdump kernel, it means amd_iommu is on in 1st kernel. > > > > I am reading doc and code, trying to debug. Please help have a look when > > convenient, see if there's hint or direction. > > Yeah, I know that this is broken on the AMD-IOMMU side. Problem is that > the IOMMU hardware needs to be disabled in the kdump kernel when > amd_iommu=off is on the command-line. I'll look into fixing that. Thanks for looking into this. This was found by our QE, I checked, and found it only happened on two HPE systems. Other AMD systems have no such issue. Since it's not a blocker, I just go to fix those urgent bugs. > > I thought we fixed this a while ago already for VT-d, is it broken > again? It's not seen in redhat's test machines, just saw Huawei engineers reported this issue. They cc-ed lkml. Thanks Baoquan ^ permalink raw reply [flat|nested] 2+ messages in thread
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2018-02-13 13:25 ` Kdump kernel hang when set amd_iommu=off Joerg Roedel
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2018-02-14 10:07 ` Baoquan He
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