linux-kernel - Re: [RFC PATCH v7 17/37] x86/apic: Unionize apic regs for 32bit/64bit access w/o type casting

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <05a9de6392a4ade9c9e70953be2a6a87a06044ca.camel@intel.com>
Date: Tue, 24 Jun 2025 10:28:17 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Neeraj.Upadhyay@....com" <Neeraj.Upadhyay@....com>
CC: "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "tiala@...rosoft.com"
	<tiala@...rosoft.com>, "Vasant.Hegde@....com" <Vasant.Hegde@....com>,
	"Suravee.Suthikulpanit@....com" <Suravee.Suthikulpanit@....com>,
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
	"Thomas.Lendacky@....com" <Thomas.Lendacky@....com>,
	"kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
	"seanjc@...gle.com" <seanjc@...gle.com>, "mingo@...hat.com"
	<mingo@...hat.com>, "pbonzini@...hat.com" <pbonzini@...hat.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>, "huibo.wang@....com"
	<huibo.wang@....com>, "Santosh.Shukla@....com" <Santosh.Shukla@....com>,
	"nikunj@....com" <nikunj@....com>, "hpa@...or.com" <hpa@...or.com>,
	"peterz@...radead.org" <peterz@...radead.org>, "bp@...en8.de" <bp@...en8.de>,
	"francescolavra.fl@...il.com" <francescolavra.fl@...il.com>,
	"naveen.rao@....com" <naveen.rao@....com>, "David.Kaplan@....com"
	<David.Kaplan@....com>, "x86@...nel.org" <x86@...nel.org>
Subject: Re: [RFC PATCH v7 17/37] x86/apic: Unionize apic regs for 32bit/64bit
 access w/o type casting


> +struct apic_page {
> +	union {
> +		u64     regs64[PAGE_SIZE / 8];
> +		u32     regs[PAGE_SIZE / 4];
> +		u8      bytes[PAGE_SIZE];
> +	};
> +} __aligned(PAGE_SIZE);

The 'bytes' field is never used.  Should it be removed?

> +
>  static inline u32 apic_get_reg(void *regs, int reg)
>  {
> -	return *((u32 *) (regs + reg));
> +	struct apic_page *ap = regs;
> +
> +	return ap->regs[reg / 4];
>  }
>  
>  static inline void apic_set_reg(void *regs, int reg, u32 val)
>  {
> -	*((u32 *) (regs + reg)) = val;
> +	struct apic_page *ap = regs;
> +
> +	ap->regs[reg / 4] = val;
>  }
>  
>  static __always_inline u64 apic_get_reg64(void *regs, int reg)
>  {
> +	struct apic_page *ap = regs;
> +
>  	BUILD_BUG_ON(reg != APIC_ICR);
> -	return *((u64 *) (regs + reg));
> +
> +	return ap->regs64[reg / 8];
>  }
>  
>  static __always_inline void apic_set_reg64(void *regs, int reg, u64 val)
>  {
> +	struct apic_page *ap = regs;
> +
>  	BUILD_BUG_ON(reg != APIC_ICR);
> -	*((u64 *) (regs + reg)) = val;
> +	ap->regs64[reg / 8] = val;
>  }
>  
>  static inline void apic_clear_vector(int vec, void *bitmap)