linux-kernel - Re: [PATCH v4] x86/vmware: use BIT() macro for shifting

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Date:   Thu, 2 Jun 2022 15:01:55 +0200
From:   "Srivatsa S. Bhat" <srivatsa@...il.mit.edu>
To:     Shreenidhi Shedi <yesshedi@...il.com>, amakhalov@...are.com,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com
Cc:     pv-drivers@...are.com, x86@...nel.org,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, Shreenidhi Shedi <sshedi@...are.com>
Subject: Re: [PATCH v4] x86/vmware: use BIT() macro for shifting

On 6/1/22 3:18 AM, Shreenidhi Shedi wrote:
> From: Shreenidhi Shedi <sshedi@...are.com>
> 
> Using BIT() macro improves readability & it uses unsigned long for
> shifting which is an added advantage.
> 
> Kernel builds with -fno-strict-overflow CFLAG hence shifting a signed
> integer by 31 bits is not an issue in this case.
> 
> Signed-off-by: Shreenidhi Shedi <sshedi@...are.com>
> ---

Looks good to me.

Reviewed-by: Srivatsa S. Bhat (VMware) <srivatsa@...il.mit.edu>

>  arch/x86/kernel/cpu/vmware.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
> index c04b933f4..02039ec35 100644
> --- a/arch/x86/kernel/cpu/vmware.c
> +++ b/arch/x86/kernel/cpu/vmware.c
> @@ -476,8 +476,8 @@ static bool __init vmware_legacy_x2apic_available(void)
>  {
>  	uint32_t eax, ebx, ecx, edx;
>  	VMWARE_CMD(GETVCPU_INFO, eax, ebx, ecx, edx);
> -	return (eax & (1 << VMWARE_CMD_VCPU_RESERVED)) == 0 &&
> -	       (eax & (1 << VMWARE_CMD_LEGACY_X2APIC)) != 0;
> +	return !(eax & BIT(VMWARE_CMD_VCPU_RESERVED)) &&
> +		(eax & BIT(VMWARE_CMD_LEGACY_X2APIC));
>  }
> 
>  #ifdef CONFIG_AMD_MEM_ENCRYPT
> --
> 2.36.1
>  
Regards,
Srivatsa
VMware Photon OS