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David Gibson authoredSome upcoming POWER machines have a system called PEF (Protected Execution Facility) which uses a small ultravisor to allow guests to run in a way that they can't be eavesdropped by the hypervisor. The effect is roughly similar to AMD SEV, although the mechanisms are quite different. Most of the work of this is done between the guest, KVM and the ultravisor, with little need for involvement by qemu. However qemu does need to tell KVM to allow secure VMs. Because the availability of secure mode is a guest visible difference which depends on having the right hardware and firmware, we don't enable this by default. In order to run a secure guest you need to create a "pef-guest" object and set the confidential-guest-support property to point to it. Note that this just *allows* secure guests, the architecture of PEF is such that the guest still needs to talk to the ultravisor to enter secure mode. Qemu has no direct way of knowing if the guest is in secure mode, and certainly can't know until well after machine creation time. To start a PEF-capable guest, use the command line options: -object pef-guest,id=pef0 -machine confidential-guest-support=pef0 Signed-off-by:
David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>David Gibson authoredSome upcoming POWER machines have a system called PEF (Protected Execution Facility) which uses a small ultravisor to allow guests to run in a way that they can't be eavesdropped by the hypervisor. The effect is roughly similar to AMD SEV, although the mechanisms are quite different. Most of the work of this is done between the guest, KVM and the ultravisor, with little need for involvement by qemu. However qemu does need to tell KVM to allow secure VMs. Because the availability of secure mode is a guest visible difference which depends on having the right hardware and firmware, we don't enable this by default. In order to run a secure guest you need to create a "pef-guest" object and set the confidential-guest-support property to point to it. Note that this just *allows* secure guests, the architecture of PEF is such that the guest still needs to talk to the ultravisor to enter secure mode. Qemu has no direct way of knowing if the guest is in secure mode, and certainly can't know until well after machine creation time. To start a PEF-capable guest, use the command line options: -object pef-guest,id=pef0 -machine confidential-guest-support=pef0 Signed-off-by:David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
papr-pef.txt 1.03 KiB
POWER (PAPR) Protected Execution Facility (PEF)
===============================================
Protected Execution Facility (PEF), also known as Secure Guest support
is a feature found on IBM POWER9 and POWER10 processors.
If a suitable firmware including an Ultravisor is installed, it adds
an extra memory protection mode to the CPU. The ultravisor manages a
pool of secure memory which cannot be accessed by the hypervisor.
When this feature is enabled in QEMU, a guest can use ultracalls to
enter "secure mode". This transfers most of its memory to secure
memory, where it cannot be eavesdropped by a compromised hypervisor.
Launching
---------
To launch a guest which will be permitted to enter PEF secure mode:
# ${QEMU} \
-object pef-guest,id=pef0 \
-machine confidential-guest-support=pef0 \
...
Live Migration
----------------
Live migration is not yet implemented for PEF guests. For
consistency, we currently prevent migration if the PEF feature is
enabled, whether or not the guest has actually entered secure mode.