Commit 0790ec17 authored Mar 17, 2015 by Radim Krčmář Committed by Marcelo Tosatti Mar 17, 2015

KVM: nVMX: mask unrestricted_guest if disabled on L0



If EPT was enabled, unrestricted_guest was allowed in L1 regardless of
L0.  L1 triple faulted when running L2 guest that required emulation.

Another side effect was 'WARN_ON_ONCE(vmx->nested.nested_run_pending)'
in L0's dmesg:
  WARNING: CPU: 0 PID: 0 at arch/x86/kvm/vmx.c:9190 nested_vmx_vmexit+0x96e/0xb00 [kvm_intel] ()

Prevent this scenario by masking SECONDARY_EXEC_UNRESTRICTED_GUEST when
the host doesn't have it enabled.

Fixes: 78051e3b ("KVM: nVMX: Disable unrestricted mode if ept=0")
Cc: stable@vger.kernel.org
Tested-By: Kashyap Chamarthy <kchamart@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

parent c5861658

arch/x86/kvm/vmx.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -2479,8 +2479,7 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
		if (enable_ept) {
		/* nested EPT: emulate EPT also to L1 */
		vmx->nested.nested_vmx_secondary_ctls_high \|=
		SECONDARY_EXEC_ENABLE_EPT \|
		SECONDARY_EXEC_UNRESTRICTED_GUEST;
		SECONDARY_EXEC_ENABLE_EPT;
		vmx->nested.nested_vmx_ept_caps = VMX_EPT_PAGE_WALK_4_BIT \|
		VMX_EPTP_WB_BIT \| VMX_EPT_2MB_PAGE_BIT \|
		VMX_EPT_INVEPT_BIT;
		@@ -2494,6 +2493,10 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
		} else
		vmx->nested.nested_vmx_ept_caps = 0;

		if (enable_unrestricted_guest)
		vmx->nested.nested_vmx_secondary_ctls_high \|=
		SECONDARY_EXEC_UNRESTRICTED_GUEST;

		/* miscellaneous data */
		rdmsr(MSR_IA32_VMX_MISC,
		vmx->nested.nested_vmx_misc_low,

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