[Xen-devel] [PATCH v1] x86/vvmx: don't enable vmcs shadowing for nested guests

[Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>]

Running "./xtf_runner vvmx" in L1 Xen under L0 Xen produces the
following result on H/W with VMCS shadowing:

    Test: vmxon
    Failure in test_vmxon_in_root_cpl0()
      Expected 0x8200000f: VMfailValid(15) VMXON_IN_ROOT
           Got 0x82004400: VMfailValid(17408) <unknown>
    Test result: FAILURE

This happens because SDM allows vmentries with enabled VMCS shadowing
VM-execution control and VMCS link pointer value of ~0ull. But results
of a nested VMREAD are undefined in such cases.

Fix this by not copying the value of VMCS shadowing control from vmcs01
to vmcs02.

Signed-off-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/vvmx.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index dde02c076b..013d049f8a 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -633,6 +633,7 @@ void nvmx_update_secondary_exec_control(struct vcpu *v,
                     SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY;
 
     host_cntrl &= ~apicv_bit;
+    host_cntrl &= ~SECONDARY_EXEC_ENABLE_VMCS_SHADOWING;
     shadow_cntrl = get_vvmcs(v, SECONDARY_VM_EXEC_CONTROL);
 
     /* No vAPIC-v support, so it shouldn't be set in vmcs12. */
-- 
2.11.0


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