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

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Message-ID: <20200421055955.GA343434@kroah.com>
Date:   Tue, 21 Apr 2020 07:59:55 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Evalds Iodzevics <evalds.iodzevics@...il.com>
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        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 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