On Thu, Mar 11, 2021 at 12:32 PM Borislav Petkov <bp@xxxxxxxxx> wrote: > > On Thu, Mar 11, 2021 at 09:07:55PM +0100, Borislav Petkov wrote: > > On Wed, Mar 10, 2021 at 07:21:23PM -0600, Babu Moger wrote: > > > # git bisect good > > > 59094faf3f618b2d2b2a45acb916437d611cede6 is the first bad commit > > > commit 59094faf3f618b2d2b2a45acb916437d611cede6 > > > Author: Borislav Petkov <bp@xxxxxxx> > > > Date: Mon Dec 25 13:57:16 2017 +0100 > > > > > > x86/kaiser: Move feature detection up > > > > What is the reproducer? > > > > Boot latest 4.9 stable kernel in a SEV guest? Can you send guest > > .config? > > > > Upthread is talking about PCID, so I'm guessing host needs to be Zen3 > > with PCID. Anything else? > > That oops points to: > > [ 1.237515] kernel BUG at /build/linux-dqnRSc/linux-4.9.228/arch/x86/kernel/alternative.c:709! > > which is: > > local_flush_tlb(); > sync_core(); > /* Could also do a CLFLUSH here to speed up CPU recovery; but > that causes hangs on some VIA CPUs. */ > for (i = 0; i < len; i++) > BUG_ON(((char *)addr)[i] != ((char *)opcode)[i]); <--- > local_irq_restore(flags); > return addr; > > in text_poke() which basically says that the patching verification > fails. And you have a local_flush_tlb() before that. And with PCID maybe > it is not flushing properly or whatnot. > > And deep down in the TLB flushing code, it does: > > if (kaiser_enabled) > kaiser_flush_tlb_on_return_to_user(); > > and that uses PCID... I would expect kaiser_enabled to be false (and PCIDs not to be used), since AMD CPUs are not vulnerable to Meltdown.
