linux-kernel - [PATCH v2 2/3] KVM: VMX: Fix enable VPID even if INVVPID is not exposed in vmx capability

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Date:   Mon, 20 Mar 2017 21:18:54 -0700
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: [PATCH v2 2/3] KVM: VMX: Fix enable VPID even if INVVPID is not exposed in vmx capability

From: Wanpeng Li <wanpeng.li@...mail.com>

This can be reproduced by running L2 on L1, and disable VPID on L0 if w/o 
commit "KVM: nVMX: Fix nested VPID vmx exec control", the L2 crash as below:

KVM: entry failed, hardware error 0x7
EAX=00000000 EBX=00000000 ECX=00000000 EDX=000306c3
ESI=00000000 EDI=00000000 EBP=00000000 ESP=00000000
EIP=0000fff0 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0000 00000000 0000ffff 00009300
CS =f000 ffff0000 0000ffff 00009b00
SS =0000 00000000 0000ffff 00009300
DS =0000 00000000 0000ffff 00009300
FS =0000 00000000 0000ffff 00009300
GS =0000 00000000 0000ffff 00009300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 0000ffff
IDT=     00000000 0000ffff
CR0=60000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 
DR6=00000000ffff0ff0 DR7=0000000000000400
EFER=0000000000000000

Reference SDM 30.3 INVVPID:
 
Protected Mode Exceptions
#UD 
  - If not in VMX operation.
  - If the logical processor does not support VPIDs (IA32_VMX_PROCBASED_CTLS2[37]=0).
  - If the logical processor supports VPIDs (IA32_VMX_PROCBASED_CTLS2[37]=1) but does 
    not support the INVVPID instruction (IA32_VMX_EPT_VPID_CAP[32]=0).

So we should check both VPID enable bit in vmx exec control and INVVPID support bit 
in vmx capability MSRs to enable VPID. This patch adds the guarantee to not enable VPID
if INVVPID is not exposed in vmx capability MSRs.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
---
 arch/x86/kvm/vmx.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 06d8080..b310214 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1239,6 +1239,11 @@ static inline bool cpu_has_vmx_invvpid_global(void)
 	return vmx_capability.vpid & VMX_VPID_EXTENT_GLOBAL_CONTEXT_BIT;
 }
 
+static inline bool cpu_has_vmx_invvpid(void)
+{
+	return vmx_capability.vpid & VMX_VPID_INVVPID_BIT;
+}
+
 static inline bool cpu_has_vmx_ept(void)
 {
 	return vmcs_config.cpu_based_2nd_exec_ctrl &
@@ -6519,8 +6524,10 @@ static __init int hardware_setup(void)
 	if (boot_cpu_has(X86_FEATURE_NX))
 		kvm_enable_efer_bits(EFER_NX);
 
-	if (!cpu_has_vmx_vpid())
+	if (!cpu_has_vmx_vpid() ||
+		!(cpu_has_vmx_invvpid()))
 		enable_vpid = 0;
+
 	if (!cpu_has_vmx_shadow_vmcs())
 		enable_shadow_vmcs = 0;
 	if (enable_shadow_vmcs)
-- 
2.7.4