linux-kernel - Re: [PATCH v3] KVM: VMX: Fix enable VPID even if INVVPID is not exposed in vmx capability

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Message-ID: <CANRm+CzUq=eY_gJs5CsNCtDBR12dLMgF4mWMAg+xSr=rBSbZvw@mail.gmail.com>
Date:   Thu, 23 Mar 2017 10:41:18 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Jim Mattson <jmattson@...gle.com>
Cc:     David Hildenbrand <david@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        kvm list <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [PATCH v3] KVM: VMX: Fix enable VPID even if INVVPID is not
 exposed in vmx capability

2017-03-23 2:20 GMT+08:00 Jim Mattson <jmattson@...gle.com>:
> Is cpu_has_vmx_invvpid() sufficient? This indicates support for the
> INVVPID instruction, but not necessarily any of the desired INVVPID
> types. KVM's vpid_sync_context() assumes that at least one of
> {VMX_VPID_EXTENT_SINGLE_CONTEXT, VMX_VPID_EXTENT_ALL_CONTEXT} is
> supported.

Good point, fix it in v4.

Regards,
Wanpeng Li

>
> On Wed, Mar 22, 2017 at 1:50 AM, David Hildenbrand <david@...hat.com> wrote:
>> On 22.03.2017 02:19, Wanpeng Li wrote:
>>> 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 | 8 +++++++-
>>>  1 file changed, 7 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>>> index 8795a70..f2b912e 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 &
>>> @@ -6518,8 +6523,9 @@ 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)
>>>
>>
>> Reviewed-by: David Hildenbrand <david@...hat.com>
>>
>> --
>>
>> Thanks,
>>
>> David