[PATCH v3 14/25] KVM: VMX: Tweak the special handling of SECONDARY_EXEC_ENCLS_EXITING in setup_vmcs_config()

Vitaly Kuznetsov
2022-07-08T14:43:44Z

SECONDARY_EXEC_ENCLS_EXITING is conditionally added to the 'optional'
checklist in setup_vmcs_config() but there's little value in doing so.
First, as the control is optional, we can always check for its
presence, no harm done. Second, the only real value cpu_has_sgx() check
gives is that on the CPUs which support SECONDARY_EXEC_ENCLS_EXITING but
don't support SGX, the control is not getting enabled. It's highly unlikely
such CPUs exist but it's possible that some hypervisors expose broken vCPU
models.

Preserve cpu_has_sgx() check but filter the result of adjust_vmx_controls()
instead of the input.

Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/kvm/vmx/vmx.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index ce54f13d8da1..566be73c6509 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2528,9 +2528,9 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
SECONDARY_EXEC_PT_CONCEAL_VMX |
SECONDARY_EXEC_ENABLE_VMFUNC |
SECONDARY_EXEC_BUS_LOCK_DETECTION |
- SECONDARY_EXEC_NOTIFY_VM_EXITING;
- if (cpu_has_sgx())
- opt2 |= SECONDARY_EXEC_ENCLS_EXITING;
+ SECONDARY_EXEC_NOTIFY_VM_EXITING |
+ SECONDARY_EXEC_ENCLS_EXITING;
+
if (adjust_vmx_controls(min2, opt2,
MSR_IA32_VMX_PROCBASED_CTLS2,
&_cpu_based_2nd_exec_control) < 0)
@@ -2577,6 +2577,9 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
vmx_cap->vpid = 0;
}

+ if (!cpu_has_sgx())
+ _cpu_based_2nd_exec_control &= ~SECONDARY_EXEC_ENCLS_EXITING;
+
if (_cpu_based_exec_control & CPU_BASED_ACTIVATE_TERTIARY_CONTROLS) {
u64 opt3 = TERTIARY_EXEC_IPI_VIRT;

--
2.35.3