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    SubjectRe: [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@amd.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.
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