Re: kern/54143 (kernel crashes with amd64 CURRENT iso in virtualbox)

[Maxime Villard <max%m00nbsd.net@localhost>]

The following reply was made to PR kern/54143; it has been noted by GNATS.

From: Maxime Villard <max%m00nbsd.net@localhost>
To: Rares Aioanei <rares.aioanei%gmail.com@localhost>, gnats-bugs%netbsd.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, gnats-admin%netbsd.org@localhost
Subject: Re: kern/54143 (kernel crashes with amd64 CURRENT iso in virtualbox)
Date: Sun, 5 May 2019 10:30:26 +0200

 Basically it faults on rdmsr(MSR_LS_CFG2), which means the MSR does not
 exist in VirtualBox. Three things that I find surprising:
 
   * At the beginning of x86_errata() we leave if there is a hypervisor, yet in
     your case it seems we don't leave. Maybe it means VirtualBox does not set
     CPUID2_RAZ?
 
   * The rdmsr is not incorrect, it corresponds to errata #1091, which does
     affect PiR-B2 (0x800f82, your CPU). The AMD spec says the workaround
     should be "Program MSRC001_102D[34] to 1b". That's exactly what we're
     doing, so there is no apparent reason for it to fault, except if VirtualBox
     does not whitelist it correctly.
 
   * It looks like we are the only ones to apply this errata, I don't see it in
     Linux or any of the other BSDs. Maybe we shouldn't be applying it?
 
 I think I will add #if0 around this errata for now.