On Thu, 21 May 2020 13:42:46 +1000 David Gibson <da...@gibson.dropbear.id.au> wrote:
> A number of hardware platforms are implementing mechanisms whereby the > hypervisor does not have unfettered access to guest memory, in order > to mitigate the security impact of a compromised hypervisor. > > AMD's SEV implements this with in-cpu memory encryption, and Intel has > its own memory encryption mechanism. POWER has an upcoming mechanism > to accomplish this in a different way, using a new memory protection > level plus a small trusted ultravisor. s390 also has a protected > execution environment. > > The current code (committed or draft) for these features has each > platform's version configured entirely differently. That doesn't seem > ideal for users, or particularly for management layers. > > AMD SEV introduces a notionally generic machine option > "machine-encryption", but it doesn't actually cover any cases other > than SEV. > > This series is a proposal to at least partially unify configuration > for these mechanisms, by renaming and generalizing AMD's > "memory-encryption" property. It is replaced by a > "guest-memory-protection" property pointing to a platform specific > object which configures and manages the specific details. > > For now this series covers just AMD SEV and POWER PEF. I'm hoping it > can be extended to cover the Intel and s390 mechanisms as well, > though. For s390, there's the 'unpack' cpu facility bit, which is indicated iff the kernel indicates availability of the feature (depending on hardware support). If that cpu facility is available, a guest can choose to transition into protected mode. The current state (protected mode or not) is tracked in the s390 ccw machine. If I understand the series here correctly (I only did a quick read-through), the user has to instruct QEMU to make protection available, via a new machine property that links to an object? > > Note: I'm using the term "guest memory protection" throughout to refer > to mechanisms like this. I don't particular like the term, it's both > long and not really precise. If someone can think of a succinct way > of saying "a means of protecting guest memory from a possibly > compromised hypervisor", I'd be grateful for the suggestion. > > Changes since v1: > * Rebased > * Fixed some errors pointed out by Dave Gilbert > > David Gibson (18): > target/i386: sev: Remove unused QSevGuestInfoClass > target/i386: sev: Move local structure definitions into .c file > target/i386: sev: Rename QSevGuestInfo > target/i386: sev: Embed SEVState in SevGuestState > target/i386: sev: Partial cleanup to sev_state global > target/i386: sev: Remove redundant cbitpos and reduced_phys_bits > fields > target/i386: sev: Remove redundant policy field > target/i386: sev: Remove redundant handle field > target/i386: sev: Unify SEVState and SevGuestState > guest memory protection: Add guest memory protection interface > guest memory protection: Handle memory encrption via interface > guest memory protection: Perform KVM init via interface > guest memory protection: Move side effect out of > machine_set_memory_encryption() > guest memory protection: Rework the "memory-encryption" property > guest memory protection: Decouple kvm_memcrypt_*() helpers from KVM > guest memory protection: Add Error ** to > GuestMemoryProtection::kvm_init > spapr: Added PEF based guest memory protection > guest memory protection: Alter virtio default properties for protected > guests > > accel/kvm/kvm-all.c | 40 +-- > accel/kvm/sev-stub.c | 5 - > accel/stubs/kvm-stub.c | 10 - > backends/Makefile.objs | 2 + > backends/guest-memory-protection.c | 29 ++ > hw/core/machine.c | 61 ++++- > hw/i386/pc_sysfw.c | 6 +- > include/exec/guest-memory-protection.h | 77 ++++++ > include/hw/boards.h | 4 +- > include/sysemu/kvm.h | 17 -- > include/sysemu/sev.h | 6 +- > target/i386/sev.c | 351 +++++++++++++------------ > target/i386/sev_i386.h | 49 ---- > target/ppc/Makefile.objs | 2 +- > target/ppc/pef.c | 81 ++++++ > 15 files changed, 441 insertions(+), 299 deletions(-) > create mode 100644 backends/guest-memory-protection.c > create mode 100644 include/exec/guest-memory-protection.h > create mode 100644 target/ppc/pef.c >
