Messages in this thread | | | Date | Mon, 13 Sep 2021 14:50:00 +0200 | From | Marek Marczykowski-Górecki <> | Subject | Linux 5.13+ as Xen dom0 crashes on Ryzen CPU (ucode loading related?) |
| |
Hi,
Since 5.13, the Xen (PV) dom0 crashes on boot, before even printing the kernel version. Test environment: - Xen 4.14.2 - AMD Ryzen 5 4500U (reported also on AMD Ryzen 7 4750U) - Linux 5.13.13, confirmed also on 5.14
The crash happens only if the initramfs has earlycpio with microcode. I don't have a serial console, but I've got a photo with crash message (from Xen, Linux doesn't managed to print anything): https://user-images.githubusercontent.com/726704/133084966-5038f37e-001b-4688-9f90-83d09be3dc2d.jpg
Transcription of some of it:
mapping kernel into physical memory about to get started (XEN) Pagetable walk from ffffffff82810888: (XEN) L4[0x1ff] = 0000000332815067 0000000000002815 (XEN) L3[0x1fe] = 0000000332816067 0000000000002816 (XEN) L2[0x014] = 0000000334018067 0000000000004018 (XEN) L1[0x010] = 0000000332810067 0000000000002810 (XEN) domain_crash_sync called from entry.S: fault at ffff82d04033e790 x86_64/entry.S#domain_crash_page_fault (XEN) Domain 0 (vcpu#0) crashed on cpu#0: (XEN) ----[ Xen-4.14.2 x86_64 debug=n Not tainted ]---- (XEN) CPU: 0 (XEN) RIP: e033:[<0000000000000000>]
I've bisected it down to the commit a799c2bd29d19c565f37fa038b31a0a1d44d0e4d
x86/setup: Consolidate early memory reservations
The early reservations of memory areas used by the firmware, bootloader, kernel text and data are spread over setup_arch(). Moreover, some of them happen *after* memblock allocations, e.g trim_platform_memory_ranges() and trim_low_memory_range() are called after reserve_real_mode() that allocates memory.
There was no corruption of these memory regions because memblock always allocates memory either from the end of memory (in top-down mode) or above the kernel image (in bottom-up mode). However, the bottom up mode is going to be updated to span the entire memory [1] to avoid limitations caused by KASLR.
Consolidate early memory reservations in a dedicated function to improve robustness against future changes. Having the early reservations in one place also makes it clearer what memory must be reserved before memblock allocations are allowed.
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Baoquan He <bhe@redhat.com> Acked-by: Borislav Petkov <bp@suse.de> Acked-by: David Hildenbrand <david@redhat.com> Link: [1] https://lore.kernel.org/lkml/20201217201214.3414100-2-guro@fb.com Link: https://lkml.kernel.org/r/20210302100406.22059-2-rppt@kernel.org
Since this seems to affect Xen boot only, I'm copying xen-devel too.
Any ideas?
-- Best Regards, Marek Marczykowski-Górecki Invisible Things Lab [unhandled content-type:application/pgp-signature] | |