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[v3,06/11] KVM: nVMX: Release enlightened VMCS on VMCLEAR

Message ID 20210526132026.270394-7-vkuznets@redhat.com (mailing list archive)
State New, archived
Headers show
Series KVM: nVMX: Fixes for nested state migration when eVMCS is in use | expand

Commit Message

Vitaly Kuznetsov May 26, 2021, 1:20 p.m. UTC
Unlike VMREAD/VMWRITE/VMPTRLD, VMCLEAR is a valid instruction when
enlightened VMCS is in use. TLFS has the following brief description:
"The L1 hypervisor can execute a VMCLEAR instruction to transition an
enlightened VMCS from the active to the non-active state". Normally,
this change can be ignored as unmapping active eVMCS can be postponed
until the next VMLAUNCH instruction but in case nested state is migrated
with KVM_GET_NESTED_STATE/KVM_SET_NESTED_STATE, keeping eVMCS mapped
may result in its synchronization with VMCS12 and this is incorrect:
L1 hypervisor is free to reuse inactive eVMCS memory for something else.

Inactive eVMCS after VMCLEAR can just be unmapped.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/kvm/vmx/nested.c | 2 ++
 1 file changed, 2 insertions(+)
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Patch

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 4d0867d5e94b..080990ebe989 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4989,6 +4989,8 @@  static int handle_vmclear(struct kvm_vcpu *vcpu)
 				     vmptr + offsetof(struct vmcs12,
 						      launch_state),
 				     &zero, sizeof(zero));
+	} else if (vmx->nested.hv_evmcs && vmptr == vmx->nested.hv_evmcs_vmptr) {
+		nested_release_evmcs(vcpu);
 	}
 
 	return nested_vmx_succeed(vcpu);