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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?enREKzFIK3BFKzl3ckluRXM5T2hVNnhpaG1nSGxwZFlQUkh1Z0JMZXA1K3BJ?= =?utf-8?B?eTZXemw3NGxsSUd2MlpOdDEreDBtTGRoOFk3eG9qaGR6Vy9EbkxqWVYzaFkx?= =?utf-8?B?UE40bHNUQTJqNStGUkliZERVNm9tT01oY01kakZxYThEYUJVclk4WmJVekU1?= =?utf-8?B?TmdCL1VlMmJrZG9CY1hUS2drRnhFNzBaNzBkTjd0SVJyK25PenVWV1U0ZnIv?= =?utf-8?B?cHNCckJldklrUXFYemVNNTBhMUtwaWxvZWxZREtXUkU2ZHMwNVdrWG1ac25j?= =?utf-8?B?LzNYR3EzRHhKL1BQSS9JK2NRRjZHTkxseTNZQzBRSWcxL2xUdGljTXM3NnA0?= =?utf-8?B?WWlPaDJyM3lPT1luUjBnRk02MmxmVWhBNSt2cDVMUE9PeExQTVhPWVEyKzQ5?= =?utf-8?B?REFGL1FNeWVEMnJiMTFWVTNxWExtRXhKVzVZV3RCTklvRGVxMVVDNGFaTzc5?= =?utf-8?B?Zlk5Umk1YjF3OVhaK0dvSHYyL2taVFVQRUhYWDhIVHdmVFlQbmtrTEpqWXNt?= =?utf-8?B?L05ET1lzSkxyQ1RTOHo0U0IrcjNQbm5uWDNOTzRnWklqd0dKWHhrRjBQY2FS?= =?utf-8?B?czN1WkRiWm1hWXdBSzY2ekZHQkplU0hMczV3RHpKUkQ1Z2R1Z0RSOE9Dekd6?= =?utf-8?B?UFZEN2pKMjBQazVDTmtmandtTUhZejNFZTE4aUhMZzlNS3QwMElvY0RjTjBQ?= =?utf-8?B?M2JnRU91TXBHSktTS2NhcTd1RFFzR01BSEd5UWdCY3Y4WjdUOHl0dFB4bThS?= =?utf-8?B?bmNtUjN2TmpKSHRVN1NwR1JZODhhSzFlSmNGYno1aEk3Vitid1Rla25LbjQ0?= =?utf-8?B?SjV2N2xKS0xPTXR1YStReW1XKzYxR0ptZHU5cXFJUzRWcHYva2t2dTNWa1F1?= =?utf-8?B?RjZwYkxmNmlFb1pHeWFCTlZCZzdsSElJOTBxV0VnWVVSM3JvQytTMmpydDVE?= =?utf-8?B?WmNIdjI3bmtxWW5xOXljK3p6VG9zTEF2ajNrdExFenpIQWNDZStHT1NIWjFz?= =?utf-8?B?RDFCb3NjSHBURjdJNk5HbzR6VmxOMElKd3F4QjVVS2s4YjNnTGVFSERrRGFQ?= =?utf-8?B?R3VWUDNEbnc1RVBQZ2xaVE9vYjk4OEtNNGdaSzZWb3lWRm9qeFBHeCtKQkFv?= =?utf-8?B?MnhpZkdoQ0ZIQ0xSdU0rNEhlUEROdEpLRHVvU3hHVFVqTGZ6T1VpeHk1OXRk?= =?utf-8?B?MHhUVkxLOHRobnUwcWdwUlpaOUhOUHFsN0dwS1pyWnpqZDNHMnpBUGd2MkZy?= =?utf-8?B?STRCWmJyR25CZ0lmMTlZWGhnQmcxR2YycFM5VGNvWFFhVGc4Q2w1UWZ6OVhu?= =?utf-8?B?WCtTVW51YWd5REdWblNFUTA0RDdrT3pTVmRxUzdiYlg3WkJOTjhpeFpKc3hW?= =?utf-8?B?dUNrV0ZJZHoweWxyZk4zSEEzcnlyTGV2R3hRdm5ib0FxdC9wUGxNbHhRYzFj?= =?utf-8?B?WjZWUmdYRXRDVlJKcGtoUS92c0JScFhFVUpyK2lVVDZ5OHZOQ1JpL1laY0xP?= =?utf-8?B?aS93SVJydldwRHQwN1ZveisvcDBKL1dlTWJua1NtWVEzNTVlbHFidmlLZ09X?= =?utf-8?B?dTBkVk5oeWV2bENPV253WTBFNDJLN3hEUlRDY1pwODdjOEVUeVhEUGRYSUVv?= =?utf-8?B?UG1xUzlsVlNhQUxiT0xpemlxR0RjaE1wSzNNUVQ4YU1VY0ZNd0U3OGVpNkNW?= =?utf-8?B?MTVFSkM4MHFRRnduTHJkUDBJV1AyUE1LQjJqdUhlRXY5YWppU1RGOERBdW1p?= =?utf-8?Q?mhFC+fbTYs4nEm/YvK1xiuMntWC7eVoAt80CWua?= X-OriginatorOrg: suse.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8977a94f-4175-4f22-c12c-08d971d60880 X-MS-Exchange-CrossTenant-AuthSource: VI1PR04MB5600.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Sep 2021 08:03:53.0520 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: hu1TXXxQgUX4yQAGIMWGiU4KgfBJPrRgpDHHA/N4HonWQ+5VX3Qc76VmIPJM98sFlCaOG+piGbGNKzSKuFvDOA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR04MB6301 On 06.09.2021 22:47, Elliott Mitchell wrote: > On Mon, Sep 06, 2021 at 09:52:17AM +0200, Jan Beulich wrote: >> On 06.09.2021 00:10, Elliott Mitchell wrote: >>> I brought this up a while back, but it still appears to be present and >>> the latest observations appear rather serious. >>> >>> I'm unsure of the entire set of conditions for reproduction. >>> >>> Domain 0 on this machine is PV (I think the BIOS enables the IOMMU, but >>> this is an older AMD IOMMU). >>> >>> This has been confirmed with Xen 4.11 and Xen 4.14. This includes >>> Debian's patches, but those are mostly backports or environment >>> adjustments. >>> >>> Domain 0 is presently using a 4.19 kernel. >>> >>> The trigger is creating a HVM or PVH domain where memory does not equal >>> maxmem. >> >> I take it you refer to "[PATCH] x86/pod: Do not fragment PoD memory >> allocations" submitted very early this year? There you said the issue >> was with a guest's maxmem exceeding host memory size. Here you seem to >> be talking of PoD in its normal form of use. Personally I uses this >> all the time (unless enabling PCI pass-through for a guest, for being >> incompatible). I've not observed any badness as severe as you've >> described. > > I've got very little idea what is occurring as I'm expecting to be doing > ARM debugging, not x86 debugging. > > I was starting to wonder whether this was widespread or not. As such I > was reporting the factors which might be different in my environment. > > The one which sticks out is the computer has an older AMD processor (you > a 100% Intel shop?). No, AMD is as relevant to us as is Intel. > The processor has the AMD NPT feature, but a very > early/limited IOMMU (according to Linux "AMD IOMMUv2 functionality not > available"). > > Xen 4.14 refused to load the Domain 0 kernel as PVH (not enough of an > IOMMU). That sounds odd at the first glance - PVH simply requires that there be an (enabled) IOMMU. Hence the only thing I could imagine is that Xen doesn't enable the IOMMU in the first place for some reason. Jan