KVM: TDX: Add an ioctl to create initial guest memory

Add a new ioctl for the user space VMM to initialize guest memory with the
specified memory contents.

Because TDX protects the guest's memory, the creation of the initial guest
memory requires a dedicated TDX module API, TDH.MEM.PAGE.ADD(), instead of
directly copying the memory contents into the guest's memory in the case of
the default VM type.

Define a new subcommand, KVM_TDX_INIT_MEM_REGION, of vCPU-scoped
KVM_MEMORY_ENCRYPT_OP.  Check if the GFN is already pre-allocated, assign
the guest page in Secure-EPT, copy the initial memory contents into the
guest memory, and encrypt the guest memory.  Optionally, extend the memory
measurement of the TDX guest.

The ioctl uses the vCPU file descriptor because of the TDX module's
requirement that the memory is added to the S-EPT (via TDH.MEM.SEPT.ADD)
prior to initialization (TDH.MEM.PAGE.ADD).  Accessing the MMU in turn
requires a vCPU file descriptor, just like for KVM_PRE_FAULT_MEMORY.  In
fact, the post-populate callback is able to reuse the same logic used by
KVM_PRE_FAULT_MEMORY, so that userspace can do everything with a single
ioctl.

Note that this is the only way to invoke TDH.MEM.SEPT.ADD before the TD
in finalized, as userspace cannot use KVM_PRE_FAULT_MEMORY at that
point.  This ensures that there cannot be pages in the S-EPT awaiting
TDH.MEM.PAGE.ADD, which would be treated incorrectly as spurious by
tdp_mmu_map_handle_target_level() (KVM would see the SPTE as PRESENT,
but the corresponding S-EPT entry will be !PRESENT).

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Co-developed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Co-developed-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
---
 - KVM_BUG_ON() for kvm_tdx->nr_premapped (Paolo)
 - Use tdx_operand_busy()
 - Merge first patch in SEPT SEAMCALL retry series in to this base
   (Paolo)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

0 files changed, 0 insertions, 0 deletions