These two patches remove some redundant code related to mode switch
and EFER emulation.
Sanity tested with kernel in L0, L1 and L2 all patched.
v2: Split to two patches and use comments from Sean to explain why
it's secure to remove them, suggested by Sean.
Zhenzhong Duan (2):
KVM: x86: Remove unnecessory assignment to uret->data
KVM: x86: Remove redundant vm_entry_controls_clearbit() call
arch/x86/kvm/vmx/vmx.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)
--
2.25.1
When emulating exit from long mode, EFER_LMA is cleared which lead to
efer writing emulation, which will unset VM_ENTRY_IA32E_MODE control
bit as requested by SDM. So no need to unset VM_ENTRY_IA32E_MODE again
in exit_lmode() explicitly.
In fact benefited from shadow controls mechanism, this change doesn't
eliminate vmread or vmwrite.
In case EFER isn't supported by hardware, long mode isn't supported,
so this will no break.
Signed-off-by: Zhenzhong Duan <[email protected]>
---
arch/x86/kvm/vmx/vmx.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index cadb3769031c..70717f56a2a2 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2907,7 +2907,6 @@ static void enter_lmode(struct kvm_vcpu *vcpu)
static void exit_lmode(struct kvm_vcpu *vcpu)
{
- vm_entry_controls_clearbit(to_vmx(vcpu), VM_ENTRY_IA32E_MODE);
vmx_set_efer(vcpu, vcpu->arch.efer & ~EFER_LMA);
}
--
2.25.1