EPC (Enclave Page Cahe) is a specialized type of memory used by Intel
SGX (Software Guard Extensions). The SDM desribes EPC as:
The Enclave Page Cache (EPC) is the secure storage used to store
enclave pages when they are a part of an executing enclave. For an
EPC page, hardware performs additional access control checks to
restrict access to the page. After the current page access checks
and translations are performed, the hardware checks that the EPC
page is accessible to the program currently executing. Generally an
EPC page is only accessed by the owner of the executing enclave or
an instruction which is setting up an EPC page.
Because of its unique requirements, Linux manages EPC separately from
normal memory. Similar to memfd, the device /dev/sgx_vepc can be
opened to obtain a file descriptor which can in turn be used to mmap()
EPC memory.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Message-Id: <20210719112136.57018-3-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Several architectures have mechanisms which are designed to protect
guest memory from interference or eavesdropping by a compromised
hypervisor. AMD SEV does this with in-chip memory encryption and
Intel's TDX can do similar things. POWER's Protected Execution
Framework (PEF) accomplishes a similar goal using an ultravisor and
new memory protection features, instead of encryption.
To (partially) unify handling for these, this introduces a new
ConfidentialGuestSupport QOM base class. "Confidential" is kind of vague,
but "confidential computing" seems to be the buzzword about these schemes,
and "secure" or "protected" are often used in connection to unrelated
things (such as hypervisor-from-guest or guest-from-guest security).
The "support" in the name is significant because in at least some of the
cases it requires the guest to take specific actions in order to protect
itself from hypervisor eavesdropping.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Sean Christopherson