From:   Thomas Gleixner <tglx@linutronix.de>
To:     Usama Arif <usama.arif@bytedance.com>, dwmw2@infradead.org,
        arjan@linux.intel.com
Cc:     mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
        hpa@zytor.com, x86@kernel.org, pbonzini@redhat.com,
        paulmck@kernel.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, rcu@vger.kernel.org, mimoja@mimoja.de,
        hewenliang4@huawei.com, thomas.lendacky@amd.com, seanjc@google.com,
        pmenzel@molgen.mpg.de, fam.zheng@bytedance.com,
        punit.agrawal@bytedance.com, simon.evans@bytedance.com,
        liangma@liangbit.com, David Woodhouse <dwmw@amazon.co.uk>,
        Usama Arif <usama.arif@bytedance.com>
Subject: Re: [PATCH v6 04/11] x86/smpboot: Reference count on
 smpboot_setup_warm_reset_vector()
In-Reply-To: <20230202215625.3248306-5-usama.arif@bytedance.com>
References: <20230202215625.3248306-1-usama.arif@bytedance.com>
 <20230202215625.3248306-5-usama.arif@bytedance.com>
Date:   Tue, 07 Feb 2023 00:48:40 +0100
Message-ID: <871qn2xsmf.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Thu, Feb 02 2023 at 21:56, Usama Arif wrote:
> From: David Woodhouse <dwmw@amazon.co.uk>
>
> If we want to do parallel CPU bringup, we're going to need to set this up
> and leave it until all CPUs are done. Might as well use the RTC spinlock
> to protect the refcount, as we need to take it anyway.

https://www.kernel.org/doc/html/latest/process/maintainer-tip.html#changelog

Aside of the 'We' this does not explain anything at all.

> [Usama Arif: fixed rebase conflict]
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> Signed-off-by: Usama Arif <usama.arif@bytedance.com>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

This SOB chain is even more broken...

> ---
>  arch/x86/kernel/smpboot.c | 21 ++++++++++++++-------
>  1 file changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index 55cad72715d9..a19eddcdccc2 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -121,17 +121,22 @@ int arch_update_cpu_topology(void)
>  	return retval;
>  }
>  
> +
> +static unsigned int smpboot_warm_reset_vector_count;
> +
>  static inline void smpboot_setup_warm_reset_vector(unsigned long start_eip)
>  {
>  	unsigned long flags;
>  
>  	spin_lock_irqsave(&rtc_lock, flags);
> -	CMOS_WRITE(0xa, 0xf);
> +	if (!smpboot_warm_reset_vector_count++) {
> +		CMOS_WRITE(0xa, 0xf);
> +		*((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_HIGH)) =
> +			start_eip >> 4;
> +		*((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) =
> +			start_eip & 0xf;

Again: 80 characters are history. Please fix that all over the series.

Thanks,

        tglx