Re: [PATCH 0/4] KVM: x86: Emulator _regs fixes and cleanups

[Robert Dinse]

     This set of patches did allow 5.18 to compile without errors using gcc 
12.1.  Thank you!

-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
 Eskimo North Linux Friendly Internet Access, Shell Accounts, and Hosting.
   Knowledgeable human assistance, not telephone trees or script readers.
 See our web site: http://www.eskimo.com/ (206) 812-0051 or (800) 246-6874.

On Wed, 25 May 2022, Sean Christopherson wrote:

> Date: Wed, 25 May 2022 22:26:00 +0000
> From: Sean Christopherson <seanjc@xxxxxxxxxx>
> To: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Sean Christopherson <seanjc@xxxxxxxxxx>,
>     Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>,
>     Wanpeng Li <wanpengli@xxxxxxxxxxx>, Jim Mattson <jmattson@xxxxxxxxxx>,
>     Joerg Roedel <joro@xxxxxxxxxx>, kvm@xxxxxxxxxxxxxxx,
>     linux-kernel@xxxxxxxxxxxxxxx, Robert Dinse <nanook@xxxxxxxxxx>,
>     Kees Cook <keescook@xxxxxxxxxxxx>
> Subject: [PATCH 0/4] KVM: x86: Emulator _regs fixes and cleanups
>
> Clean up and harden the use of the x86_emulate_ctxt._regs, which is
> surrounded by a fair bit of magic.  This series was prompted by bug reports
> by Kees and Robert where GCC-12 flags an out-of-bounds _regs access.  I'm
> 99% certain GCC-12 is wrong and is generating a false positive, but just in
> case...
>
> I didn't tag patch 2 with Fixes or Cc: stable@; if it turns out to "fix"
> the GCC-12 compilation error, it's probably worth sending to v5.18 stable
> tree (KVM hasn't changed, but the warning=>error was "introdued in v5.18
> by commit e6148767825c ("Makefile: Enable -Warray-bounds")).
>
> Sean Christopherson (4):
>  KVM: x86: Grab regs_dirty in local 'unsigned long'
>  KVM: x86: Harden _regs accesses to guard against buggy input
>  KVM: x86: Omit VCPU_REGS_RIP from emulator's _regs array
>  KVM: x86: Use 16-bit fields to track dirty/valid emulator GPRs
>
> arch/x86/kvm/emulate.c     | 14 ++++++++++++--
> arch/x86/kvm/kvm_emulate.h | 14 +++++++++++---
> 2 files changed, 23 insertions(+), 5 deletions(-)
>
>
> base-commit: 90bde5bea810d766e7046bf5884f2ccf76dd78e9
> --
> 2.36.1.124.g0e6072fb45-goog