Re: [Xen-devel] [PATCH v7 27/36] iommu/amd: Allow the AMD IOMMU to work with memory encryption

[Tom Lendacky <thomas.lendacky@xxxxxxx>]

On 6/22/2017 5:56 AM, Borislav Petkov wrote:
> On Fri, Jun 16, 2017 at 01:54:59PM -0500, Tom Lendacky wrote:
> > The IOMMU is programmed with physical addresses for the various tables
> > and buffers that are used to communicate between the device and the
> > driver. When the driver allocates this memory it is encrypted. In order
> > for the IOMMU to access the memory as encrypted the encryption mask needs
> > to be included in these physical addresses during configuration.
> >
> > The PTE entries created by the IOMMU should also include the encryption
> > mask so that when the device behind the IOMMU performs a DMA, the DMA
> > will be performed to encrypted memory.
> >
> > Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> > ---
> >   drivers/iommu/amd_iommu.c       |   30 ++++++++++++++++--------------
> >   drivers/iommu/amd_iommu_init.c  |   34 ++++++++++++++++++++++++++++------
> >   drivers/iommu/amd_iommu_proto.h |   10 ++++++++++
> >   drivers/iommu/amd_iommu_types.h |    2 +-
> >   4 files changed, 55 insertions(+), 21 deletions(-)
> Reviewed-by: Borislav Petkov <bp@xxxxxxx>
>
> Btw, I'm assuming the virt_to_phys() difference on SME systems is only
> needed in a handful of places. Otherwise, I'd suggest changing the
> virt_to_phys() function/macro directly. But I guess most of the places
> need the real physical address without the enc bit.
Correct.

Thanks,
Tom

>
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