[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH v10 00/38] x86: Secure Memory Encryption (AMD)

On 7/18/2017 7:03 AM, Thomas Gleixner wrote:
On Mon, 17 Jul 2017, Tom Lendacky wrote:
This patch series provides support for AMD's new Secure Memory Encryption (SME)

SME can be used to mark individual pages of memory as encrypted through the
page tables. A page of memory that is marked encrypted will be automatically
decrypted when read from DRAM and will be automatically encrypted when
written to DRAM. Details on SME can found in the links below.

The SME feature is identified through a CPUID function and enabled through
the SYSCFG MSR. Once enabled, page table entries will determine how the
memory is accessed. If a page table entry has the memory encryption mask set,
then that memory will be accessed as encrypted memory. The memory encryption
mask (as well as other related information) is determined from settings
returned through the same CPUID function that identifies the presence of the

The approach that this patch series takes is to encrypt everything possible
starting early in the boot where the kernel is encrypted. Using the page
table macros the encryption mask can be incorporated into all page table
entries and page allocations. By updating the protection map, userspace
allocations are also marked encrypted. Certain data must be accounted for
as having been placed in memory before SME was enabled (EFI, initrd, etc.)
and accessed accordingly.

This patch series is a pre-cursor to another AMD processor feature called
Secure Encrypted Virtualization (SEV). The support for SEV will build upon
the SME support and will be submitted later. Details on SEV can be found
in the links below.

Well done series. Thanks to all people involved, especially Tom and Boris!
It was a pleasure to review that.

Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

A big thanks from me to everyone that helped review this.  I truly
appreciate all the time that everyone put into this - especially Boris,
who helped guide this series from the start.


Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.