linux-kernel - Re: [PATCH v6 24/34] x86, swiotlb: Add memory encryption support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 14 Jun 2017 18:45:53 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     linux-arch@...r.kernel.org, linux-efi@...r.kernel.org,
        kvm@...r.kernel.org, linux-doc@...r.kernel.org, x86@...nel.org,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        iommu@...ts.linux-foundation.org, Rik van Riel <riel@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Toshimitsu Kani <toshi.kani@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Larry Woodman <lwoodman@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dave Young <dyoung@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v6 24/34] x86, swiotlb: Add memory encryption support

On Wed, Jun 07, 2017 at 02:17:21PM -0500, Tom Lendacky wrote:
> Since DMA addresses will effectively look like 48-bit addresses when the
> memory encryption mask is set, SWIOTLB is needed if the DMA mask of the
> device performing the DMA does not support 48-bits. SWIOTLB will be
> initialized to create decrypted bounce buffers for use by these devices.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> ---

...


> diff --git a/init/main.c b/init/main.c
> index df58a41..7125b5f 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -488,6 +488,10 @@ void __init __weak thread_stack_cache_init(void)
>  }
>  #endif
>  
> +void __init __weak mem_encrypt_init(void)
> +{
> +}

void __init __weak mem_encrypt_init(void) { }

saves some real estate. Please do that for the rest of the stubs you're
adding, for the next version.

> +
>  /*
>   * Set up kernel memory allocators
>   */
> @@ -640,6 +644,15 @@ asmlinkage __visible void __init start_kernel(void)
>  	 */
>  	locking_selftest();
>  
> +	/*
> +	 * This needs to be called before any devices perform DMA
> +	 * operations that might use the SWIOTLB bounce buffers.
> +	 * This call will mark the bounce buffers as decrypted so
> +	 * that their usage will not cause "plain-text" data to be
> +	 * decrypted when accessed.

s/This call/It/

> +	 */
> +	mem_encrypt_init();
> +
>  #ifdef CONFIG_BLK_DEV_INITRD
>  	if (initrd_start && !initrd_below_start_ok &&
>  	    page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> index a8d74a7..74d6557 100644
> --- a/lib/swiotlb.c
> +++ b/lib/swiotlb.c
> @@ -30,6 +30,7 @@
>  #include <linux/highmem.h>
>  #include <linux/gfp.h>
>  #include <linux/scatterlist.h>
> +#include <linux/mem_encrypt.h>
>  
>  #include <asm/io.h>
>  #include <asm/dma.h>
> @@ -155,6 +156,17 @@ unsigned long swiotlb_size_or_default(void)
>  	return size ? size : (IO_TLB_DEFAULT_SIZE);
>  }
>  
> +void __weak swiotlb_set_mem_attributes(void *vaddr, unsigned long size)
> +{
> +}

As above.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.