linux-kernel - Re: [patch V2 19/52] x86/kvm: Avoid looking up PKRU in XSAVE buffer

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Date:   Thu, 17 Jun 2021 14:09:31 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Yu-cheng Yu <yu-cheng.yu@...el.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: Re: [patch V2 19/52] x86/kvm: Avoid looking up PKRU in XSAVE buffer

On Mon, Jun 14, 2021 at 05:44:27PM +0200, Thomas Gleixner wrote:
> @@ -4632,18 +4633,20 @@ static void load_xsave(struct kvm_vcpu *
>  	 */
>  	valid = xstate_bv & ~XFEATURE_MASK_FPSSE;
>  	while (valid) {
> +		u32 size, offset, ecx, edx;
>  		u64 xfeature_mask = valid & -valid;
>  		int xfeature_nr = fls64(xfeature_mask) - 1;
> -		void *dest = get_xsave_addr(xsave, xfeature_nr);
>  
> -		if (dest) {
> -			u32 size, offset, ecx, edx;
> -			cpuid_count(XSTATE_CPUID, xfeature_nr,
> -				    &size, &offset, &ecx, &edx);
> -			if (xfeature_nr == XFEATURE_PKRU)
> -				memcpy(&vcpu->arch.pkru, src + offset,
> -				       sizeof(vcpu->arch.pkru));
> -			else
> +		cpuid_count(XSTATE_CPUID, xfeature_nr,
> +			    &size, &offset, &ecx, &edx);
> +
> +		if (xfeature_nr == XFEATURE_PKRU) {
> +			memcpy(&vcpu->arch.pkru, src + offset,
> +			       sizeof(vcpu->arch.pkru));
> +		} else {
> +			void *dest = get_xsave_addr(xsave, xfeature_nr);
> +

With that superfluous newline removed:

Reviewed-by: Borislav Petkov <bp@...e.de>

> +			if (dest)
>  				memcpy(dest, src + offset, size);
>  		}

-- 
Regards/Gruss,
    Boris.

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