linux-kernel - Re: v6.13-rc1: Internal error: Oops - Undefined instruction: 0000000002000000 [#1] SMP

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Message-ID: <20241205020946.yf6xdieoswsrmvi5@altlinux.org>
Date: Thu, 5 Dec 2024 05:09:46 +0300
From: Vitaly Chikunov <vt@...linux.org>
To: Oliver Upton <oliver.upton@...ux.dev>
Cc: Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>,
	james.morse@....com, linux-arm-kernel@...ts.infradead.org,
	Catalin Marinas <catalin.marinas@....com>,
	linux-kernel@...r.kernel.org, mark.rutland@....com
Subject: Re: v6.13-rc1: Internal error: Oops - Undefined instruction:
 0000000002000000 [#1] SMP

Oliver,

On Tue, Dec 03, 2024 at 07:03:50AM +0300, Vitaly Chikunov wrote:
> On Mon, Dec 02, 2024 at 05:19:54PM -0800, Oliver Upton wrote:
> > On Tue, Dec 03, 2024 at 01:31:19AM +0300, Vitaly Chikunov wrote:
> > > Marc,
> > > 
> > > On Mon, Dec 02, 2024 at 04:07:03PM +0000, Marc Zyngier wrote:
> > > > On Mon, 02 Dec 2024 15:59:40 +0000,
> > > > Vitaly Chikunov <vt@...linux.org> wrote:
> > > > > 
> > > > > Marc,
> > > > > 
> > > > > On Mon, Dec 02, 2024 at 03:53:59PM +0000, Marc Zyngier wrote:
> > > > > >
> > > > > > What the log doesn't say is what the host is. Is it 6.13-rc1 as well?
> > > > > 
> > > > > No, host is 6.6.60.
> > > > 
> > > > Right. I wouldn't be surprised if:
> > > > 
> > > > - this v6.6 kernel doesn't hide the MPAM feature as it should (and
> > > >   that's proably something we should backport)
> > > 
> > > How to confirm this? Currently I cannot find any (case-insensitive)
> > > "MPAM" files in /sys, nor mpam string in /proc/cpuinfo, nor MPAM strings
> > > in `strace -v` (as it decodes some KVM ioctls) of qemu process.
> > 
> > If you can attach to the QEMU gdbstub of the VM, info registers will
> > dump ~everything.
> > 
> > If the value of ID_AA64PFR0_EL1.MPAM (bits 43:40) is nonzero then the
> > host KVM is erroneously advertising MPAM to the guest.
> 
> I don't find such register. There is what I get:

Thanks to ArmCpuInfo.efi I can confirm MPAM is advertised.

  Shell> ArmCpuInfo.efi
  ID_AA64PFR0_EL1  = 0x1100010011111111
  ...
  PFR0  | MPAM         | 43:40 |  0001 | FEAT_MPAM v1.0 implemented.

I prepared the kernel with Marc's patch (backport of 6685f5d572c22e10 to
6.6) and am waiting for the admins to boot it, hopefully today or tomorrow.

Thanks,