Arthur Chunqi Li wrote on 2013-09-04:
> This patch contains the following two changes:
> 1. Fix the bug in nested preemption timer support. If vmexit L2->L0 with some
> reasons not emulated by L1, preemption timer value should be save in such
> exits.
> 2. Add support of "Save VMX-preemption timer value" VM-Exit controls to
> nVMX.
> 
> With this patch, nested VMX preemption timer features are fully supported.
> 
> Signed-off-by: Arthur Chunqi Li <yzt...@gmail.com>
> ---
> This series depends on queue.
> 
>  arch/x86/include/uapi/asm/msr-index.h |    1 +
>  arch/x86/kvm/vmx.c                    |   51
> ++++++++++++++++++++++++++++++---
>  2 files changed, 48 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/include/uapi/asm/msr-index.h
> b/arch/x86/include/uapi/asm/msr-index.h
> index bb04650..b93e09a 100644
> --- a/arch/x86/include/uapi/asm/msr-index.h
> +++ b/arch/x86/include/uapi/asm/msr-index.h
> @@ -536,6 +536,7 @@
> 
>  /* MSR_IA32_VMX_MISC bits */
>  #define MSR_IA32_VMX_MISC_VMWRITE_SHADOW_RO_FIELDS (1ULL << 29)
> +#define MSR_IA32_VMX_MISC_PREEMPTION_TIMER_SCALE   0x1F
>  /* AMD-V MSRs */
> 
>  #define MSR_VM_CR                       0xc0010114
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 1f1da43..870caa8
> 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2204,7 +2204,14 @@ static __init void
> nested_vmx_setup_ctls_msrs(void)  #ifdef CONFIG_X86_64
>               VM_EXIT_HOST_ADDR_SPACE_SIZE |
>  #endif
> -             VM_EXIT_LOAD_IA32_PAT | VM_EXIT_SAVE_IA32_PAT;
> +             VM_EXIT_LOAD_IA32_PAT | VM_EXIT_SAVE_IA32_PAT |
> +             VM_EXIT_SAVE_VMX_PREEMPTION_TIMER;
> +     if (!(nested_vmx_pinbased_ctls_high &
> PIN_BASED_VMX_PREEMPTION_TIMER))
> +             nested_vmx_exit_ctls_high &=
> +                     (~VM_EXIT_SAVE_VMX_PREEMPTION_TIMER);
> +     if (!(nested_vmx_exit_ctls_high &
> VM_EXIT_SAVE_VMX_PREEMPTION_TIMER))
> +             nested_vmx_pinbased_ctls_high &=
> +                     (~PIN_BASED_VMX_PREEMPTION_TIMER);
The following logic is more clearly:
if(nested_vmx_pinbased_ctls_high & PIN_BASED_VMX_PREEMPTION_TIMER)
        nested_vmx_exit_ctls_high |= VM_EXIT_SAVE_VMX_PREEMPTION_TIMER

BTW: I don't see nested_vmx_setup_ctls_msrs() considers the hardware's 
capability when expose those vmx features(not just preemption timer) to L1. 

>       nested_vmx_exit_ctls_high |=
> (VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR |
>                                     VM_EXIT_LOAD_IA32_EFER);
> 
> @@ -6707,6 +6714,23 @@ static void vmx_get_exit_info(struct kvm_vcpu
> *vcpu, u64 *info1, u64 *info2)
>       *info2 = vmcs_read32(VM_EXIT_INTR_INFO);  }
> 
> +static void nested_adjust_preemption_timer(struct kvm_vcpu *vcpu) {
> +     u64 delta_tsc_l1;
> +     u32 preempt_val_l1, preempt_val_l2, preempt_scale;
> +
> +     preempt_scale = native_read_msr(MSR_IA32_VMX_MISC) &
> +                     MSR_IA32_VMX_MISC_PREEMPTION_TIMER_SCALE;
> +     preempt_val_l2 = vmcs_read32(VMX_PREEMPTION_TIMER_VALUE);
> +     delta_tsc_l1 = kvm_x86_ops->read_l1_tsc(vcpu,
> +                     native_read_tsc()) - vcpu->arch.last_guest_tsc;
> +     preempt_val_l1 = delta_tsc_l1 >> preempt_scale;
> +     if (preempt_val_l2 - preempt_val_l1 < 0)
> +             preempt_val_l2 = 0;
> +     else
> +             preempt_val_l2 -= preempt_val_l1;
> +     vmcs_write32(VMX_PREEMPTION_TIMER_VALUE, preempt_val_l2); }
>  /*
>   * The guest has exited.  See if we can fix it or if we need userspace
>   * assistance.
> @@ -6716,6 +6740,7 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
>       struct vcpu_vmx *vmx = to_vmx(vcpu);
>       u32 exit_reason = vmx->exit_reason;
>       u32 vectoring_info = vmx->idt_vectoring_info;
> +     int ret;
> 
>       /* If guest state is invalid, start emulating */
>       if (vmx->emulation_required)
> @@ -6795,12 +6820,15 @@ static int vmx_handle_exit(struct kvm_vcpu
> *vcpu)
> 
>       if (exit_reason < kvm_vmx_max_exit_handlers
>           && kvm_vmx_exit_handlers[exit_reason])
> -             return kvm_vmx_exit_handlers[exit_reason](vcpu);
> +             ret = kvm_vmx_exit_handlers[exit_reason](vcpu);
>       else {
>               vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
>               vcpu->run->hw.hardware_exit_reason = exit_reason;
> +             ret = 0;
>       }
> -     return 0;
> +     if (is_guest_mode(vcpu))
> +             nested_adjust_preemption_timer(vcpu);
Move this forward to avoid the changes for ret.
> +     return ret;
>  }
> 
>  static void update_cr8_intercept(struct kvm_vcpu *vcpu, int tpr, int irr) @@
> -7518,6 +7546,7 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu,
> struct vmcs12 *vmcs12)  {
>       struct vcpu_vmx *vmx = to_vmx(vcpu);
>       u32 exec_control;
> +     u32 exit_control;
> 
>       vmcs_write16(GUEST_ES_SELECTOR, vmcs12->guest_es_selector);
>       vmcs_write16(GUEST_CS_SELECTOR, vmcs12->guest_cs_selector); @@
> -7691,7 +7720,10 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu,
> struct vmcs12 *vmcs12)
>        * we should use its exit controls. Note that VM_EXIT_LOAD_IA32_EFER
>        * bits are further modified by vmx_set_efer() below.
>        */
> -     vmcs_write32(VM_EXIT_CONTROLS, vmcs_config.vmexit_ctrl);
> +     exit_control = vmcs_config.vmexit_ctrl;
> +     if (vmcs12->pin_based_vm_exec_control &
> PIN_BASED_VMX_PREEMPTION_TIMER)
> +             exit_control |= VM_EXIT_SAVE_VMX_PREEMPTION_TIMER;
> +     vmcs_write32(VM_EXIT_CONTROLS, exit_control);
And here should be problem if host doesn't support 
VM_EXIT_SAVE_VMX_PREEMPTION_TIMER.

> 
>       /* vmcs12's VM_ENTRY_LOAD_IA32_EFER and VM_ENTRY_IA32E_MODE
> are
>        * emulated by vmx_set_efer(), below.
> @@ -8090,6 +8122,17 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu,
> struct vmcs12 *vmcs12)
>       vmcs12->guest_pending_dbg_exceptions =
>               vmcs_readl(GUEST_PENDING_DBG_EXCEPTIONS);
> 
> +     if (vmcs12->pin_based_vm_exec_control &
> +                     PIN_BASED_VMX_PREEMPTION_TIMER) {
> +             if (vmcs12->vm_exit_controls &
> +                             VM_EXIT_SAVE_VMX_PREEMPTION_TIMER)
> +                     vmcs12->vmx_preemption_timer_value =
> +                             vmcs_read32(VMX_PREEMPTION_TIMER_VALUE);
> +             else
> +                     vmcs_write32(VMX_PREEMPTION_TIMER_VALUE,
> +                                     vmcs12->vmx_preemption_timer_value);
Why write it to vmcs directly if VM_EXIT_SAVE_VMX_PREEMPTION_TIMER not set?

> +     }
> +
>       /*
>        * In some cases (usually, nested EPT), L2 is allowed to change its
>        * own CR3 without exiting. If it has changed it, we must keep it.
> --
> 1.7.9.5
> 
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in the body of 
> a
> message to majord...@vger.kernel.org More majordomo info at
> http://vger.kernel.org/majordomo-info.html

Best regards,
Yang


--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Reply via email to