From 64d19f333464a877f3ebe538510a10a514db0eb9 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Fri, 8 Jan 2021 13:23:09 +1100 Subject: [PATCH] confidential guest support: Update documentation Now that we've implemented a generic machine option for configuring various confidential guest support mechanisms: 1. Update docs/amd-memory-encryption.txt to reference this rather than the earlier SEV specific option 2. Add a docs/confidential-guest-support.txt to cover the generalities of the confidential guest support scheme Signed-off-by: David Gibson Reviewed-by: Greg Kurz --- docs/amd-memory-encryption.txt | 2 +- docs/confidential-guest-support.txt | 43 +++++++++++++++++++++++++++++ 2 files changed, 44 insertions(+), 1 deletion(-) create mode 100644 docs/confidential-guest-support.txt diff --git a/docs/amd-memory-encryption.txt b/docs/amd-memory-encryption.txt index 80b8eb00e9..145896aec7 100644 --- a/docs/amd-memory-encryption.txt +++ b/docs/amd-memory-encryption.txt @@ -73,7 +73,7 @@ complete flow chart. To launch a SEV guest # ${QEMU} \ - -machine ...,memory-encryption=sev0 \ + -machine ...,confidential-guest-support=sev0 \ -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=1 Debugging diff --git a/docs/confidential-guest-support.txt b/docs/confidential-guest-support.txt new file mode 100644 index 0000000000..bd439ac800 --- /dev/null +++ b/docs/confidential-guest-support.txt @@ -0,0 +1,43 @@ +Confidential Guest Support +========================== + +Traditionally, hypervisors such as QEMU have complete access to a +guest's memory and other state, meaning that a compromised hypervisor +can compromise any of its guests. A number of platforms have added +mechanisms in hardware and/or firmware which give guests at least some +protection from a compromised hypervisor. This is obviously +especially desirable for public cloud environments. + +These mechanisms have different names and different modes of +operation, but are often referred to as Secure Guests or Confidential +Guests. We use the term "Confidential Guest Support" to distinguish +this from other aspects of guest security (such as security against +attacks from other guests, or from network sources). + +Running a Confidential Guest +---------------------------- + +To run a confidential guest you need to add two command line parameters: + +1. Use "-object" to create a "confidential guest support" object. The + type and parameters will vary with the specific mechanism to be + used +2. Set the "confidential-guest-support" machine parameter to the ID of + the object from (1). + +Example (for AMD SEV):: + + qemu-system-x86_64 \ + \ + -machine ...,confidential-guest-support=sev0 \ + -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=1 + +Supported mechanisms +-------------------- + +Currently supported confidential guest mechanisms are: + +AMD Secure Encrypted Virtualization (SEV) + docs/amd-memory-encryption.txt + +Other mechanisms may be supported in future.