Messages in this thread | | | From | Juergen Gross <> | Subject | Re: Linux 5.13+ as Xen dom0 crashes on Ryzen CPU (ucode loading related?) | Date | Tue, 14 Sep 2021 09:14:38 +0200 |
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On 13.09.21 14:50, Marek Marczykowski-Górecki wrote: > 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>]
The domain's run state seems to be completely clobbered.
Did you try to boot the kernel with "earlyprintk=xen" to get some idea how far it progressed?
I could imagine that doing the early reservations after the call of e820__memory_setup() is problematic, as Xen PV guests have a hook in this function performing some rather extended actions.
I'm not sure the call of early_reserve_memory() can be moved just before the e820__memory_setup() call. If this is possibel it should be done IMO, if not then the reservations which have been at the start of setup_arch() might need to go there again.
Juergen
> > 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? >
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