linux-kernel - Re: [PATCH v2] x86/microcode/intel: replace sync_core() with native_cpuid

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Date:   Tue, 21 Apr 2020 09:19:02 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Evalds Iodzevics <evalds.iodzevics@...il.com>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ben Hutchings <ben@...adent.org.uk>
Subject: Re: [PATCH v2] x86/microcode/intel: replace sync_core() with
 native_cpuid_reg(eax)

On Tue, Apr 21, 2020 at 09:41:42AM +0300, Evalds Iodzevics wrote:
> On Tue, Apr 21, 2020 at 8:59 AM Greg KH <gregkh@...uxfoundation.org> wrote:
> >
> > On Tue, Apr 21, 2020 at 11:53:44AM +0300, Evalds Iodzevics wrote:
> > > On Intel it is required to do CPUID(1) before reading the microcode
> > > revision MSR. Current code in 4.4 an 4.9 relies on sync_core() to call
> > > CPUID, unfortunately on 32 bit machines code inside sync_core() always
> > > jumps past CPUID instruction as it depends on data structure boot_cpu_data
> > > witch are not populated correctly so early in boot sequence.
> > >
> > > It depends on:
> > > commit 5dedade6dfa2 ("x86/CPU: Add native CPUID variants returning a single
> > > datum")
> > >
> > > This patch is for 4.4 but also should apply to 4.9
> > >
> > > Signed-off-by: Evalds Iodzevics <evalds.iodzevics@...il.com>
> > > ---
> > >  arch/x86/include/asm/microcode_intel.h | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > Why are you not sending this to the stable mailing list like I have
> > pointed out numerous times by sending you a link to _how_ to get a patch
> > into the stable kernel trees?
> >
> > Again, here it is:
> >     https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> >
> > Please follow that so that we can do this correctly.
> >
> > thanks,
> >
> > greg k-h
> Sorry, I might sound dumb here but should i just send it to
> stable@...r.kernel.org or try to tag it Cc: stable... in sign-off
> area, its quite confusing for newcomer.

Yes, be sure to cc: the stable@...r.kernel.org list when you send
patches that you want to have applied to a stable kernel tree.

thanks,

greg k-h