From: Greg KH <gregkh@linuxfoundation.org>
To: Niels Dettenbach <nd@syndicat.com>
Cc: linux-arch@vger.kernel.org, stable@vger.kernel.org, trivial@kernel.org
Subject: Re: [PATCH 1/1] x86: SMT broken on Xen PV DomU since 6.9 (updated)
Date: Thu, 12 Sep 2024 07:21:55 +0200 [thread overview]
Message-ID: <2024091258-quickness-clapping-7418@gregkh> (raw)
In-Reply-To: <3301863.oiGErgHkdL@gongov>
On Wed, Sep 11, 2024 at 05:49:46PM +0200, Niels Dettenbach wrote:
> Am Mittwoch, 11. September 2024, 10:53:30 schrieb Niels Dettenbach:
> > virtual machines under Xen Hypervisor (DomU) running in Xen PV mode use a
> > special, nonstandard synthetized CPU topology which "just works" under
> > kernels 6.9.x while newer kernels assuming a "crash kernel" and disable
> > SMT (reducing to one CPU core) because the newer topology implementation
> > produces a wrong error "[Firmware Bug]: APIC enumeration order not
> > specification compliant" after new topology checks which are improper for
> > Xen PV platform. As a result, the kernel disables SMT and activates just
> > one CPU core within the VM (DomU).
> >
> > The patch disables the regarding checks if it is running in Xen PV
> > mode (only) and bring back SMT / all CPUs as in the past to such DomU
> > VMs.
> >
> > Signed-off-by: Niels Dettenbach <nd@syndicat.com>
> >
>
> Signed-off-by: Niels Dettenbach <nd@syndicat.com>
> ---
>
> A reworked proposal patch which substitutes my initial proposed patch:
>
>
> --- linux/arch/x86/kernel/cpu/topology.c 2024-09-11 17:42:42.699278317 +0200
> +++ linux/arch/x86/kernel/cpu/topology.c.orig 2024-09-11 09:53:16.194095250 +0200
<snip>
Please submit this to the proper developers and maintainers for this
code, as the get_maintainers script will tell you as the documentation
states. As it is, this isn't going anywhere as you did not include them
properly.
good luck!
greg k-h
prev parent reply other threads:[~2024-09-12 5:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-11 8:53 [PATCH 1/1] x86: SMT broken on Xen PV DomU since 6.9 Niels Dettenbach
2024-09-11 15:49 ` [PATCH 1/1] x86: SMT broken on Xen PV DomU since 6.9 (updated) Niels Dettenbach
2024-09-12 5:21 ` Greg KH [this message]
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