linux-kernel - Re: [PATCH v5 2/8] x86/sev: Add support for the RMPREAD instruction

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Message-ID: <20241112184046.GBZzOhLrqFxSfdZ968@fat_crate.local>
Date: Tue, 12 Nov 2024 19:40:46 +0100
From: Borislav Petkov <bp@...en8.de>
To: Tom Lendacky <thomas.lendacky@....com>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Michael Roth <michael.roth@....com>,
	Ashish Kalra <ashish.kalra@....com>,
	Nikunj A Dadhania <nikunj@....com>,
	Neeraj Upadhyay <Neeraj.Upadhyay@....com>
Subject: Re: [PATCH v5 2/8] x86/sev: Add support for the RMPREAD instruction

On Mon, Oct 28, 2024 at 02:32:37PM -0500, Tom Lendacky wrote:
> +	if (cpu_feature_enabled(X86_FEATURE_RMPREAD)) {
> +		int ret;
> +
> +		/* RMPREAD */

Now that we know:

		/* Supported in binutils version 2.44 */

> +		asm volatile(".byte 0xf2, 0x0f, 0x01, 0xfd"
> +			     : "=a" (ret)
> +			     : "a" (pfn << PAGE_SHIFT), "c" (e)
> +			     : "memory", "cc");
> +

-- 
Regards/Gruss,
    Boris.

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