linux-kernel - Re: [PATCHv10 05/18] x86/kexec: Keep CR4.MCE set during kexec for TDX guest

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Date: Tue, 30 Apr 2024 17:49:08 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Borislav Petkov <bp@...en8.de>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>, Elena Reshetova <elena.reshetova@...el.com>, 
	Jun Nakajima <jun.nakajima@...el.com>, Rick Edgecombe <rick.p.edgecombe@...el.com>, 
	Tom Lendacky <thomas.lendacky@....com>, "Kalra, Ashish" <ashish.kalra@....com>, 
	Sean Christopherson <seanjc@...gle.com>, "Huang, Kai" <kai.huang@...el.com>, Baoquan He <bhe@...hat.com>, 
	kexec@...ts.infradead.org, linux-coco@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv10 05/18] x86/kexec: Keep CR4.MCE set during kexec for
 TDX guest

On Tue, Apr 30, 2024 at 03:03:23PM +0200, Borislav Petkov wrote:
> On Tue, Apr 09, 2024 at 02:29:57PM +0300, Kirill A. Shutemov wrote:
> > +1:
> > +	testq	$X86_CR4_MCE, %r13
> > +	jz	1f
> > +	ALTERNATIVE "", __stringify(orl $X86_CR4_MCE, %eax), X86_FEATURE_TDX_GUEST
> >  1:
> 
> Please add the below patch to your set. Those same-number labels are
> just abominable.
> 
> Thx.
> 
> ---
> From: "Borislav Petkov (AMD)" <bp@...en8.de>
> Date: Tue, 30 Apr 2024 15:00:16 +0200
> Subject: [PATCH] x86/relocate_kernel: Use named labels for less confusion
> 
> That identity_mapped() function was loving that "1" label to the point
> of completely confusing its readers.
> 
> Use named labels in each place for clarity.
> 
> No functional changes.
> 
> Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
> ---
>  arch/x86/kernel/relocate_kernel_64.S | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
> index 8e2037d78a1f..0077c9e562a7 100644
> --- a/arch/x86/kernel/relocate_kernel_64.S
> +++ b/arch/x86/kernel/relocate_kernel_64.S
> @@ -152,13 +152,15 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
>  	 */
>  	movl	$X86_CR4_PAE, %eax
>  	testq	$X86_CR4_LA57, %r13
> -	jz	1f
> +	jz	no_la57
>  	orl	$X86_CR4_LA57, %eax
> -1:
> +no_la57:

I assume all of these new labels have to be prefixed with ".L", right?

-- 
  Kiryl Shutsemau / Kirill A. Shutemov