On 09/22/2016 02:11 PM, Borislav Petkov wrote:

On Thu, Sep 22, 2016 at 02:04:27PM -0500, Tom Lendacky wrote:

quoted

That's not what I mean here.  If the BIOS sets the SMEE bit in the
SYS_CFG msr then, even if the encryption bit is never used, there is
still a reduction in physical address space.

I thought that reduction is the reservation of bits for the SME mask.

What other reduction is there?

There is a reduction in physical address space for the SME mask and the
bits used to aid in identifying the ASID associated with the memory
request. This allows for the memory controller to determine the key to
be used for the encryption operation (host/hypervisor key vs. an SEV
guest key).

Thanks,
Tom

quoted

Transparent SME (TSME) will be a BIOS option that will result in the
memory controller performing encryption no matter what. In this case
all data will be encrypted without a reduction in physical address
space.

Now I'm confused: aren't we reducing the address space with the SME
mask?

Or what reduction do you mean?

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