linux-kernel - Re: [PATCH v1 1/7] x86/mm: Move force_dma

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Date:   Fri, 11 Jun 2021 09:43:51 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>
Cc:     Peter H Anvin <hpa@...or.com>, Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/7] x86/mm: Move force_dma_unencrypted() to common
 code

On 6/9/21 4:55 PM, Kuppuswamy Sathyanarayanan wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
> 
> diff --git a/arch/x86/mm/mem_encrypt_common.c b/arch/x86/mm/mem_encrypt_common.c
> new file mode 100644
> index 000000000000..4a9a4d5f36cd
> --- /dev/null
> +++ b/arch/x86/mm/mem_encrypt_common.c
> @@ -0,0 +1,20 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Memory Encryption Support Common Code
> + *
> + * Copyright (C) 2021 Intel Corporation
> + *
> + * Author: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> + */
> +
> +#include <asm/mem_encrypt_common.h>
> +#include <linux/dma-mapping.h>
> +
> +/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
> +bool force_dma_unencrypted(struct device *dev)
> +{
> +	if (sev_active() || sme_active())
> +		return amd_force_dma_unencrypted(dev);
> +
> +	return false;

Until other stuff is added, this should probably just be:

	return amd_force_dma_unencrypted(dev);

Thanks,
Tom

> +}
>