linux-kernel - Re: [PATCH 15/14] x86/gds: Lock GDS mitigation when keylocker feature is present

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Date: Fri, 19 Apr 2024 11:03:28 -0700
From: Daniel Sneddon <daniel.sneddon@...ux.intel.com>
To: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
 linux-kernel@...r.kernel.org
Cc: x86@...nel.org, dan.j.williams@...el.com, bernie.keany@...el.com,
 charishma1.gairuboyina@...el.com, chang.seok.bae@...el.com,
 Josh Poimboeuf <jpoimboe@...nel.org>, antonio.gomez.iglesias@...ux.intel.com
Subject: Re: [PATCH 15/14] x86/gds: Lock GDS mitigation when keylocker feature
 is present

On 4/19/24 10:47, Pawan Gupta wrote:
> +	u64 gds_lock = 0;
>  
>  	switch (gds_mitigation) {
>  	case GDS_MITIGATION_OFF:
> @@ -769,6 +769,8 @@ void update_gds_msr(void)
>  		 * the same state. Make sure the mitigation is enabled on all
>  		 * CPUs.
>  		 */
> +		gds_lock = GDS_MITG_LOCKED;
Can't we just drop the new gds_lock var and set mcu_ctrl |= GDS_MITG_LOCKED here?
> +		fallthrough;
>  	case GDS_MITIGATION_FULL:
>  		rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
>  		mcu_ctrl &= ~GDS_MITG_DIS;
> @@ -779,6 +781,7 @@ void update_gds_msr(void)
>  		return;
>  	}
>  
> +	mcu_ctrl |= gds_lock;
>  	wrmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);