linux-kernel - Re: [PATCH v3 2/2] x86/head64: Replace pointer fixups with RIP_RELATIVE

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Date: Wed, 31 Jan 2024 10:22:52 +0200
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Kevin Loughlin <kevinloughlin@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	Nick Desaulniers <ndesaulniers@...gle.com>, Justin Stitt <justinstitt@...gle.com>, 
	Tom Lendacky <thomas.lendacky@....com>, Pankaj Gupta <pankaj.gupta@....com>, 
	Hou Wenlong <houwenlong.hwl@...group.com>, Ard Biesheuvel <ardb@...nel.org>, 
	Dionna Glaze <dionnaglaze@...gle.com>, Brijesh Singh <brijesh.singh@....com>, 
	Michael Roth <michael.roth@....com>, linux-kernel@...r.kernel.org, llvm@...ts.linux.dev, 
	linux-coco@...ts.linux.dev, Ashish Kalra <ashish.kalra@....com>, 
	Andi Kleen <ak@...ux.intel.com>, Adam Dunlap <acdunlap@...gle.com>, 
	Peter Gonda <pgonda@...gle.com>, Jacob Xu <jacobhxu@...gle.com>, 
	Sidharth Telang <sidtelang@...gle.com>
Subject: Re: [PATCH v3 2/2] x86/head64: Replace pointer fixups with
 RIP_RELATIVE_ADDR()

On Tue, Jan 30, 2024 at 10:08:45PM +0000, Kevin Loughlin wrote:
> @@ -594,15 +579,15 @@ static void set_bringup_idt_handler(gate_desc *idt, int n, void *handler)
>  /* This runs while still in the direct mapping */
>  static void __head startup_64_load_idt(unsigned long physbase)
>  {
> -	struct desc_ptr *desc = fixup_pointer(&bringup_idt_descr, physbase);
> -	gate_desc *idt = fixup_pointer(bringup_idt_table, physbase);
> +	struct desc_ptr *desc = RIP_RELATIVE_ADDR(bringup_idt_descr);
> +	gate_desc *idt = RIP_RELATIVE_ADDR(bringup_idt_table);
>  
>  
>  	if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {
>  		void *handler;
>  
>  		/* VMM Communication Exception */
> -		handler = fixup_pointer(vc_no_ghcb, physbase);
> +		handler = RIP_RELATIVE_ADDR(vc_no_ghcb);
>  		set_bringup_idt_handler(idt, X86_TRAP_VC, handler);
>  	}
>  

Looks like you removed all physbase users in the function. No need to pass
it to it.

> @@ -629,7 +614,7 @@ void early_setup_idt(void)
>  void __head startup_64_setup_env(unsigned long physbase)
>  {
>  	/* Load GDT */
> -	startup_gdt_descr.address = (unsigned long)fixup_pointer(startup_gdt, physbase);
> +	startup_gdt_descr.address = (unsigned long)RIP_RELATIVE_ADDR(startup_gdt);
>  	native_load_gdt(&startup_gdt_descr);
>  
>  	/* New GDT is live - reload data segment registers */

With startup_64_load_idt() fixed, no users for physbase in this function
either.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov