On 18/10/2017 17:39, Jim Mattson wrote:
> As long as we're taking the "better safe than sorry" approach, why
> don't we go ahead and clear vmx_capability.ept/vmx_capability.vpid
> along with the warnings?
Indeed.
Paolo
> On Tue, Oct 17, 2017 at 6:43 PM, Wanpeng Li <kernellwp@xxxxxxxxx> wrote:
>> From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
>>
>> In my setup, EPT is not exposed to L1, the VPID capability is exposed and
>> can be observed by vmxcap tool in L1:
>> INVVPID supported yes
>> Individual-address INVVPID yes
>> Single-context INVVPID yes
>> All-context INVVPID yes
>> Single-context-retaining-globals INVVPID yes
>>
>> However, the module parameter of VPID observed in L1 is always N, the
>> cpu_has_vmx_invvpid() check in L1 KVM fails since vmx_capability.vpid
>> is 0 and it is not read from MSR due to EPT is not exposed.
>>
>> The VPID can be used to tag linear mappings when EPT is not enabled. However,
>> current logic just detects VPID capability if EPT is enabled, this patch
>> fixes it.
>>
>> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
>> Cc: Jim Mattson <jmattson@xxxxxxxxxx>
>> Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
>> ---
>> v2 -> v3:
>> * add pr_warn_once
>> v1 -> v2:
>> * rdmsr_safe instead of rdmsr
>> * add more explanation to patch description
>>
>> arch/x86/kvm/vmx.c | 13 ++++++++++---
>> 1 file changed, 10 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index 3644540..c14e981 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -3681,15 +3681,22 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
>> SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
>> SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY);
>>
>> + rdmsr_safe(MSR_IA32_VMX_EPT_VPID_CAP,
>> + &vmx_capability.ept, &vmx_capability.vpid);
>> +
>> if (_cpu_based_2nd_exec_control & SECONDARY_EXEC_ENABLE_EPT) {
>> /* CR3 accesses and invlpg don't need to cause VM Exits when EPT
>> enabled */
>> _cpu_based_exec_control &= ~(CPU_BASED_CR3_LOAD_EXITING |
>> CPU_BASED_CR3_STORE_EXITING |
>> CPU_BASED_INVLPG_EXITING);
>> - rdmsr(MSR_IA32_VMX_EPT_VPID_CAP,
>> - vmx_capability.ept, vmx_capability.vpid);
>> - }
>> + } else if (vmx_capability.ept)
>> + pr_warn_once("EPT CAP should not exist if not support "
>> + "1-setting enable EPT VM-execution control\n");
>> + if (!(_cpu_based_2nd_exec_control & SECONDARY_EXEC_ENABLE_VPID) &&
>> + vmx_capability.vpid)
>> + pr_warn_once("VPID CAP should not exist if not support "
>> + "1-setting enable VPID VM-execution control\n");
>>
>> min = VM_EXIT_SAVE_DEBUG_CONTROLS | VM_EXIT_ACK_INTR_ON_EXIT;
>> #ifdef CONFIG_X86_64
>> --
>> 2.7.4
>>
