On 2013-08-25 09:37, Arthur Chunqi Li wrote: > On Sun, Aug 25, 2013 at 3:28 PM, Jan Kiszka <jan.kiszka@xxxxxx> wrote: >> On 2013-08-25 09:24, Arthur Chunqi Li wrote: >>> On Sun, Aug 25, 2013 at 2:44 PM, Jan Kiszka <jan.kiszka@xxxxxx> wrote: >>>> On 2013-08-24 20:44, root wrote: >>>>> 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 <yzt356@xxxxxxxxx> >>>>> --- >>>>> arch/x86/kvm/vmx.c | 30 +++++++++++++++++++++++++----- >>>>> 1 file changed, 25 insertions(+), 5 deletions(-) >>>>> >>>>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >>>>> index 57b4e12..9579409 100644 >>>>> --- a/arch/x86/kvm/vmx.c >>>>> +++ b/arch/x86/kvm/vmx.c >>>>> @@ -2204,7 +2204,8 @@ 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; >>>>> nested_vmx_exit_ctls_high |= (VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR | >>>>> VM_EXIT_LOAD_IA32_EFER); >>>> >>>> In the absence of VM_EXIT_SAVE_VMX_PREEMPTION_TIMER, you need to hide >>>> PIN_BASED_VMX_PREEMPTION_TIMER from the guest as we cannot emulate its >>>> behavior properly in that case. > Besides, we need to test that in the absence of > PIN_BASED_VMX_PREEMPTION_TIMER, we need to hide > VM_EXIT_SAVE_VMX_PREEMPTION_TIMER, though this should not happen > according to Intel SDM. If the SDM guarantees this for us, we don't need such a safety measure. Otherwise, it should be added, yes. Jan
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