On 10/25/22 19:21, Sean Christopherson wrote:
Shortlog scope is still wrong, should be "KVM: nVMX:"
The shortlog is also somewhat is misleading/confusing, as it's not at all obvious that "sgx enabled" means "KVM's sgx_module param is enabled" and not "SGX is enabled in the system".
E.g.
KVM: nVMX: Advertise ENCLS_EXITING to L1 iff SGX is fully supported
Queued with this commit message:
--- KVM: VMX: fully disable SGX if SECONDARY_EXEC_ENCLS_EXITING unavailable
Clear enable_sgx if ENCLS-exiting is not supported, i.e. if SGX cannot be virtualized. When KVM is loaded, adjust_vmx_controls checks that the bit is available before enabling the feature; however, other parts of the code check enable_sgx and not clearing the variable caused two different bugs, mostly affecting nested virtualization scenarios.
First, because enable_sgx remained true, SECONDARY_EXEC_ENCLS_EXITING would be marked available in the capability MSR that are accessed by a nested hypervisor. KVM would then propagate the control from vmcs12 to vmcs02 even if it isn't supported by the processor, thus causing an unexpected VM-Fail (exit code 0x7) in L1.
Second, vmx_set_cpu_caps() would not clear the SGX bits when hardware support is unavailable. This is a much less problematic bug as it only happens if SGX is soft-disabled (available in the processor but hidden in CPUID) or if SGX is supported for bare metal but not in the VMCS (will never happen when running on bare metal, but can theoertically happen when running in a VM).
Last but not least, this ensures that module params in sysfs reflect KVM's actual configuration.
RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=2127128 Fixes: 72add915fbd5 ("KVM: VMX: Enable SGX virtualization for SGX1, SGX2 and LC") Cc: stable@vger.kernel.org Suggested-by: Sean Christopherson seanjc@google.com Suggested-by: Bandan Das bsd@redhat.com Signed-off-by: Emanuele Giuseppe Esposito eesposit@redhat.com Message-Id: 20221025123749.2201649-1-eesposit@redhat.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com ---
The bug is strictly speaking not in nVMX, although that's where most of the symptoms surface.
Paolo