[PATCH 4.20 62/92] x86/kvm/nVMX: read from MSR_IA32_VMX_PROCBASED_CTLS2 only when it is available

[Greg Kroah-Hartman]

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>

commit 6b1971c694975e49af302229202c0043568b1791 upstream.

SDM says MSR_IA32_VMX_PROCBASED_CTLS2 is only available "If
(CPUID.01H:ECX.[5] && IA32_VMX_PROCBASED_CTLS[63])". It was found that
some old cpus (namely "Intel(R) Core(TM)2 CPU 6600 @ 2.40GHz (family: 0x6,
model: 0xf, stepping: 0x6") don't have it. Add the missing check.

Reported-by: Zdenek Kaspar <zkaspar82@xxxxxxxxx>
Tested-by: Zdenek Kaspar <zkaspar82@xxxxxxxxx>
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/kvm/vmx.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3620,9 +3620,11 @@ static void nested_vmx_setup_ctls_msrs(s
 	 * secondary cpu-based controls.  Do not include those that
 	 * depend on CPUID bits, they are added later by vmx_cpuid_update.
 	 */
-	rdmsr(MSR_IA32_VMX_PROCBASED_CTLS2,
-		msrs->secondary_ctls_low,
-		msrs->secondary_ctls_high);
+	if (msrs->procbased_ctls_high & CPU_BASED_ACTIVATE_SECONDARY_CONTROLS)
+		rdmsr(MSR_IA32_VMX_PROCBASED_CTLS2,
+		      msrs->secondary_ctls_low,
+		      msrs->secondary_ctls_high);
+
 	msrs->secondary_ctls_low = 0;
 	msrs->secondary_ctls_high &=
 		SECONDARY_EXEC_DESC |