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Date: Mon, 3 Jun 2024 17:24:00 -0700
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Subject: Re: [PATCHv11 05/19] x86/relocate_kernel: Use named labels for less
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To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Nikolay Borisov <nik.borisov@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>,
        Elena Reshetova <elena.reshetova@intel.com>,
        Jun Nakajima <jun.nakajima@intel.com>,
        Rick Edgecombe <rick.p.edgecombe@intel.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        "Kalra, Ashish"
 <ashish.kalra@amd.com>,
        Sean Christopherson <seanjc@google.com>,
        "Huang, Kai" <kai.huang@intel.com>, Ard Biesheuvel <ardb@kernel.org>,
        Baoquan He <bhe@redhat.com>, "K. Y. Srinivasan" <kys@microsoft.com>,
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        linux-hyperv@vger.kernel.org, linux-acpi@vger.kernel.org,
        linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org
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From: "H. Peter Anvin" <hpa@zytor.com>
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Trying one more time; sorry (again) if someone receives this in duplicate.

>>>
>>> diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
>>> index 56cab1bb25f5..085eef5c3904 100644
>>> --- a/arch/x86/kernel/relocate_kernel_64.S
>>> +++ b/arch/x86/kernel/relocate_kernel_64.S
>>> @@ -148,9 +148,10 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
>>>    	 */
>>>    	movl	$X86_CR4_PAE, %eax
>>>    	testq	$X86_CR4_LA57, %r13
>>> -	jz	1f
>>> +	jz	.Lno_la57
>>>    	orl	$X86_CR4_LA57, %eax
>>> -1:
>>> +.Lno_la57:
>>> +
>>>    	movq	%rax, %cr4

If we are cleaning up this code... the above can simply be:

	andl $(X86_CR4_PAE | X86_CR4_LA54), %r13
	movq %r13, %cr4

%r13 is dead afterwards, and the PAE bit *will* be set in %r13 anyway.

	-hpa