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?
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
>
