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Tue, 18 Aug 2026 23:50:10 -0700 (PDT) Message-ID: <4a1b5392-93b9-4b9e-bf65-3fb280f385fa@suse.com> Date: Wed, 19 Aug 2026 08:50:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [BUG] Linux kernel crash in amd_smn_init during PVH Dom0 boot on AMD EPYC To: Arthur Borsboom References: Content-Language: en-US Cc: xen-devel@lists.xenproject.org From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-purgate-ID: tlsNG-ef75cf/1787122211-A76D2AE4-2A90C0CA/0/0 X-purgate-type: clean X-purgate-size: 4685 On 18.08.2026 23:47, Arthur Borsboom wrote: > Hi, > > I am encountering an early Linux kernel crash when booting a PVH > Dom0 on an AMD EPYC system (Family 19h Model 97). PV boot on the > same system works fine. The crash occurs during amd_smn_init due > to a divide-by-zero exception. > > There is a potentially related bug report discussing a Linux patch > addressing AMD SMN initialization under Xen PVH: > > https://patchew.org/linux/20260623211904.3674-1-jason.andryuk@amd.com/ > > It seems there was an ongoing discussion between Linux devs who > seem to have the need to align with Xen devs for a proper/future-proof fix. > I am submitting this report to share raw hardware trace data and > help move this forward. > > --- System Details --- > CPU: AMD EPYC 4344P 8-Core Processor (Family 25 / 0x19, Model 97 > / 0x61, Stepping 2) > Motherboard: MSI MSIS366/S3661 (BIOS ES366AOC.10P 05/29/2025) > Xen Version: 4.20.0 (Command line: dom0_mem=8192M,max:8192M dom0=pvh > loglvl=all guest_loglvl=all sync_console noreboot console=com1,vga) > Linux Kernel: 7.1.5-arch1-2 > > --- Kernel Crash Log --- > [...] > [ 0.817348] Oops: divide error: 0000 [#1] SMP NOPTI > [ 0.817348] fbcon: Taking over console > [ 0.823766] CPU: 3 UID: 0 PID: 1 Comm: swapper/0 Not tainted > 7.1.5-arch1-2 #1 PREEMPT(full) > 33708094282b4038de0f4f0d201b68f6a0b5d9bf > [ 0.839766] Hardware name: MSI MSIS366/S3661, BIOS ES366AOC.10P 05/29/2025 > [ 0.847766] RIP: 0010:amd_smn_init+0x1ed/0x280 > [ 0.852766] Code: d2 45 31 f6 45 31 ed 66 41 f7 f4 89 c5 48 89 df > e8 c8 c7 1b fd 48 89 c3 48 85 c0 0f 84 48 ff ff ff 44 89 e8 31 d2 45 > 8d 7d 01 <66> f7 f5 66 85 d2 75 42 66 90 eb 2c 41 0f b7 ce 48 8d b3 d0 > 00 00 > [ 0.870766] RSP: 0018:ffffc9000004bdc8 EFLAGS: 00010246 > [ 0.878766] RAX: 0000000000000000 RBX: ffff888102661000 RCX: 0000000000000007 > [ 0.887766] RDX: 0000000000000000 RSI: ffff888102661000 RDI: 0000000000000000 > [ 0.895766] RBP: 0000000000000000 R08: 0000000000000282 R09: ffff888100f57680 > [ 0.903766] R10: ffffea0004044580 R11: ffff888100042700 R12: 0000000000000002 > [ 0.911766] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001 > [ 0.919766] FS: 0000000000000000(0000) GS:ffff8882b2010000(0000) > knlGS:0000000000000000 > [ 0.927766] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 0.935766] CR2: 0000000000000000 CR3: 0000000003822000 CR4: 0000000000750ef0 > [ 0.943766] PKRU: 55555554 > [ 0.943766] Call Trace: > [ 0.948766] > [ 0.951766] ? __pfx_amd_smn_init+0x10/0x10 > [ 0.956766] do_one_initcall+0x8e/0x3f0 > [ 0.959766] kernel_init_freeable+0x24a/0x2d0 > [ 0.965766] ? __pfx_kernel_init+0x10/0x10 > [ 0.967766] kernel_init+0x1a/0x140 > [ 0.973766] ret_from_fork+0x2a7/0x330 > [ 0.974766] ? __pfx_kernel_init+0x10/0x10 > [ 0.982766] ret_from_fork_asm+0x1a/0x30 > [ 0.988766] > [ 0.989766] Modules linked in: > [ 0.994772] ---[ end trace 0000000000000000 ]--- > [ 0.999769] RIP: 0010:amd_smn_init+0x1ed/0x280 > [ 1.004770] Code: d2 45 31 f6 45 31 ed 66 41 f7 f4 89 c5 48 89 df > e8 c8 c7 1b fd 48 89 c3 48 85 c0 0f 84 48 ff ff ff 44 89 e8 31 d2 45 > 8d 7d 01 <66> f7 f5 66 85 d2 75 42 66 90 eb 2c 41 0f b7 ce 48 8d b3 d0 > 00 00 > [ 1.004771] RSP: 0018:ffffc9000004bdc8 EFLAGS: 00010246 > [ 1.004773] RAX: 0000000000000000 RBX: ffff888102661000 RCX: 0000000000000007 > [ 1.004774] RDX: 0000000000000000 RSI: ffff888102661000 RDI: 0000000000000000 > [ 1.004775] RBP: 0000000000000000 R08: 0000000000000282 R09: ffff888100f57680 > [ 1.004776] R10: ffffea0004044580 R11: ffff888100042700 R12: 0000000000000002 > [ 1.004777] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001 > [ 1.004778] FS: 0000000000000000(0000) GS:ffff8882b2090000(0000) > knlGS:0000000000000000 > [ 1.004779] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 1.004780] CR2: 0000000000000000 CR3: 0000000003822000 CR4: 0000000000750ef0 > [ 1.004782] PKRU: 55555554 > [ 1.004784] Kernel panic - not syncing: Attempted to kill init! > exitcode=0x0000000b > (XEN) Hardware Dom0 crashed: 'noreboot' set - not rebooting. > > Please let me know if any additional info would be helpful. Well, a pretty natural question: What amount of research have you done yourself? You really should have found [1], or maybe its v1 counterpart, or the earlier report(s) of what I think is this same issue. Jan [1] https://patchew.org/linux/20260814214255.83127-1-jason.andryuk@amd.com/20260814214255.83127-2-jason.andryuk@amd.com/