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

From: Borislav Petkov
Date: Thu Jun 22 2017 - 06:57:11 EST

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.


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