Re: [Part2 PATCH v9 00/38] x86: Secure Encrypted Virtualization (AMD)

From: Brijesh Singh
Date: Thu Dec 21 2017 - 10:51:31 EST

On 12/21/17 7:06 AM, Paolo Bonzini wrote:

Hi Paolo,

> Hi Brijesh,
> I have a couple comments:
> 1) how is MSR_AMD64_SEV's value passed to the guest, and where is it in
> the manual?

It is a non interceptable read-only MSR set by the HW when SEV feature
is enabled in VMRUN instruction.
> 2) ECX should be 0 in the guest's 0x8000_001f leaf, because we don't
> support nested SEV guests. Likewise, EAX bit 2 should be 0 since you
> don't emulate the page flush MSR.

IIRC, I do clear both EAX Page_Flush and nested virtualization case from
Qemu SEV feature is enabled.
> Both can be fixed on top (and I can do the second myself of course), so
> there should be no need for a v10.