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From: Tom Lendacky <thomas.lendacky@amd.com>
To: Borislav Petkov <bp@alien8.de>, X86 ML <x86@kernel.org>
Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com>,
	Ashok Raj <ashok.raj@intel.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/7] x86/microcode: Do not upload microcode if CPUs are offline
Date: Mon, 5 Mar 2018 16:06:48 -0600	[thread overview]
Message-ID: <236a3244-c4df-0d40-72c0-583ca9f47fd6@amd.com> (raw)
In-Reply-To: <20180228102846.13447-5-bp@alien8.de>

On 2/28/2018 4:28 AM, Borislav Petkov wrote:
> From: Ashok Raj <ashok.raj@intel.com>
> 
> Avoid loading microcode if any of the CPUs are offline, and issue a
> warning. Having different microcode revisions on the system at any time
> is outright dangerous.
> 
> Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> Cc: x86-ml <x86@kernel.org>
> Link: http://lkml.kernel.org/r/1519352533-15992-4-git-send-email-ashok.raj@intel.com
> [ Massage it. ]
> Signed-off-by: Borislav Petkov <bp@suse.de>
> ---
>  arch/x86/kernel/cpu/microcode/core.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>

> diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
> index 63370651e376..fa32cb3dcca5 100644
> --- a/arch/x86/kernel/cpu/microcode/core.c
> +++ b/arch/x86/kernel/cpu/microcode/core.c
> @@ -486,6 +486,16 @@ static void __exit microcode_dev_exit(void)
>  /* fake device for request_firmware */
>  static struct platform_device	*microcode_pdev;
>  
> +static int check_online_cpus(void)
> +{
> +	if (num_online_cpus() == num_present_cpus())
> +		return 0;
> +
> +	pr_err("Not all CPUs online, aborting microcode update.\n");
> +
> +	return -EINVAL;
> +}
> +
>  static enum ucode_state reload_for_cpu(int cpu)
>  {
>  	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
> @@ -519,7 +529,13 @@ static ssize_t reload_store(struct device *dev,
>  		return size;
>  
>  	get_online_cpus();
> +
> +	ret = check_online_cpus();
> +	if (ret)
> +		goto put;
> +
>  	mutex_lock(&microcode_mutex);
> +
>  	for_each_online_cpu(cpu) {
>  		tmp_ret = reload_for_cpu(cpu);
>  		if (tmp_ret > UCODE_NFOUND) {
> @@ -538,6 +554,8 @@ static ssize_t reload_store(struct device *dev,
>  		microcode_check();
>  
>  	mutex_unlock(&microcode_mutex);
> +
> +put:
>  	put_online_cpus();
>  
>  	if (!ret)
> 

  parent reply	other threads:[~2018-03-05 22:06 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-28 10:28 [PATCH 0/7] x86/microcode: Improve late loading Borislav Petkov
2018-02-28 10:28 ` [PATCH 1/7] x86/microcode: Get rid of struct apply_microcode_ctx Borislav Petkov
2018-03-08  9:25   ` [tip:x86/pti] " tip-bot for Borislav Petkov
2018-02-28 10:28 ` [PATCH 2/7] x86/microcode/intel: Check microcode revision before updating sibling threads Borislav Petkov
2018-03-08  9:25   ` [tip:x86/pti] " tip-bot for Ashok Raj
2018-02-28 10:28 ` [PATCH 3/7] x86/microcode/intel: Writeback and invalidate caches before updating microcode Borislav Petkov
2018-03-08  9:26   ` [tip:x86/pti] " tip-bot for Ashok Raj
2018-02-28 10:28 ` [PATCH 4/7] x86/microcode: Do not upload microcode if CPUs are offline Borislav Petkov
2018-02-28 13:11   ` Henrique de Moraes Holschuh
2018-02-28 13:26     ` Raj, Ashok
2018-02-28 19:07       ` Henrique de Moraes Holschuh
2018-03-05 22:06   ` Tom Lendacky [this message]
2018-03-08  9:26   ` [tip:x86/pti] " tip-bot for Ashok Raj
2018-02-28 10:28 ` [PATCH 5/7] x86/microcode/intel: Look into the patch cache first Borislav Petkov
2018-03-08  9:27   ` [tip:x86/pti] " tip-bot for Borislav Petkov
2018-02-28 10:28 ` [PATCH 6/7] x86/microcode: Request microcode on the BSP Borislav Petkov
2018-03-05 22:08   ` Tom Lendacky
2018-03-08  9:27   ` [tip:x86/pti] " tip-bot for Borislav Petkov
2018-02-28 10:28 ` [PATCH 7/7] x86/microcode: Synchronize late microcode loading Borislav Petkov
2018-02-28 13:59   ` Henrique de Moraes Holschuh
2018-02-28 14:08     ` Borislav Petkov
2018-02-28 17:48       ` Henrique de Moraes Holschuh
2018-03-05 22:09   ` Tom Lendacky
2018-03-08  9:28   ` [tip:x86/pti] " tip-bot for Ashok Raj
2018-03-05 22:12 ` [PATCH 0/7] x86/microcode: Improve late loading Tom Lendacky
2018-03-05 23:51   ` Raj, Ashok

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