i386: Update SGX CPUID info according to hardware/KVM/user input

Expose SGX to the guest if and only if KVM is enabled and supports
virtualization of SGX.  While the majority of ENCLS can be emulated to
some degree, because SGX uses a hardware-based root of trust, the
attestation aspects of SGX cannot be emulated in software, i.e.
ultimately emulation will fail as software cannot generate a valid
quote/report.  The complexity of partially emulating SGX in Qemu far
outweighs the value added, e.g. an SGX specific simulator for userspace
applications can emulate SGX for development and testing purposes.

Note, access to the PROVISIONKEY is not yet advertised to the guest as
KVM blocks access to the PROVISIONKEY by default and requires userspace
to provide additional credentials (via ioctl()) to expose PROVISIONKEY.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Message-Id: <20210719112136.57018-13-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 668e48be8a..5748d7c55f 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -195,6 +195,9 @@ void pc_system_parse_ovmf_flash(uint8_t *flash_ptr, size_t flash_size);
 void pc_madt_cpu_entry(AcpiDeviceIf *adev, int uid,
                        const CPUArchIdList *apic_ids, GArray *entry);
 
+/* sgx.c */
+void pc_machine_init_sgx_epc(PCMachineState *pcms);
+
 extern GlobalProperty pc_compat_6_1[];
 extern const size_t pc_compat_6_1_len;