Re: [PATCH 2/5] KVM: nVMX: add KVM_CAP_HYPERV_ENLIGHTENED_VMCS capability

From: Vitaly Kuznetsov
Date: Fri Jun 15 2018 - 06:34:59 EST

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Previous message: Vitaly Kuznetsov: "Re: [PATCH 3/5] KVM: nVMX: add enlightened VMCS state"
In reply to: Liran Alon: "Re: [PATCH 2/5] KVM: nVMX: add KVM_CAP_HYPERV_ENLIGHTENED_VMCS capability"
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Liran Alon <liran.alon@xxxxxxxxxx> writes:

> ----- vkuznets@xxxxxxxxxx wrote:
>
>> Enlightened VMCS is opt-in. The current version does not contain all
>> fields supported by nested VMX so we must not advertise the
>> corresponding VMX features if enlightened VMCS is enabled.
>>
>> Userspace is given the enlightened VMCS version supported by KVM as
>> part of enabling KVM_CAP_HYPERV_ENLIGHTENED_VMCS. The version is to
>> be advertised to the nested hypervisor, currently done via a cpuid
>> leaf for Hyper-V.
>>
>> Suggested-by: Ladi Prosek <lprosek@xxxxxxxxxx>
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
>> ---
>> arch/x86/include/asm/kvm_host.h | 3 +
>> arch/x86/kvm/svm.c | 9 +++
>> arch/x86/kvm/vmx.c | 138
>> ++++++++++++++++++++++------------------
>> arch/x86/kvm/x86.c | 15 +++++
>> include/uapi/linux/kvm.h | 1 +
>> 5 files changed, 105 insertions(+), 61 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/kvm_host.h
>> b/arch/x86/include/asm/kvm_host.h
>> index 0ebe659f2802..d7e8f7155d79 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -1095,6 +1095,9 @@ struct kvm_x86_ops {
>> int (*mem_enc_unreg_region)(struct kvm *kvm, struct kvm_enc_region
>> *argp);
>>
>> int (*get_msr_feature)(struct kvm_msr_entry *entry);
>> +
>> + int (*nested_enable_evmcs)(struct kvm_vcpu *vcpu,
>> + uint16_t *vmcs_version);
>> };
>>
>> struct kvm_arch_async_pf {
>> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
>> index d9305f1723f5..6dc42c870565 100644
>> --- a/arch/x86/kvm/svm.c
>> +++ b/arch/x86/kvm/svm.c
>> @@ -7009,6 +7009,13 @@ static int svm_unregister_enc_region(struct kvm
>> *kvm,
>> return ret;
>> }
>>
>> +static int nested_enable_evmcs(struct kvm_vcpu *vcpu,
>> + uint16_t *vmcs_version)
>> +{
>> + /* Intel-only feature */
>> + return -ENODEV;
>> +}
>> +
>> static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
>> .cpu_has_kvm_support = has_svm,
>> .disabled_by_bios = is_disabled,
>> @@ -7135,6 +7142,8 @@ static struct kvm_x86_ops svm_x86_ops
>> __ro_after_init = {
>> .mem_enc_op = svm_mem_enc_op,
>> .mem_enc_reg_region = svm_register_enc_region,
>> .mem_enc_unreg_region = svm_unregister_enc_region,
>> +
>> + .nested_enable_evmcs = nested_enable_evmcs,
>> };
>>
>> static int __init svm_init(void)
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index 48989f78be60..51749207cef1 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -648,6 +648,13 @@ struct nested_vmx {
>>
>> bool change_vmcs01_virtual_apic_mode;
>>
>> + /*
>> + * Enlightened VMCS has been enabled. It does not mean that L1 has
>> to
>> + * use it. However, VMX features available to L1 will be limited
>> based
>> + * on what the enlightened VMCS supports.
>> + */
>> + bool enlightened_vmcs_enabled;
>> +
>> /* L2 must run next, and mustn't decide to exit to L1. */
>> bool nested_run_pending;
>>
>> @@ -1186,6 +1193,49 @@ DEFINE_STATIC_KEY_FALSE(enable_evmcs);
>>
>> #define KVM_EVMCS_VERSION 1
>>
>> +/*
>> + * Enlightened VMCSv1 doesn't support these:
>> + *
>> + * POSTED_INTR_NV = 0x00000002,
>> + * GUEST_INTR_STATUS = 0x00000810,
>> + * APIC_ACCESS_ADDR = 0x00002014,
>> + * POSTED_INTR_DESC_ADDR = 0x00002016,
>> + * EOI_EXIT_BITMAP0 = 0x0000201c,
>> + * EOI_EXIT_BITMAP1 = 0x0000201e,
>> + * EOI_EXIT_BITMAP2 = 0x00002020,
>> + * EOI_EXIT_BITMAP3 = 0x00002022,
>> + * GUEST_PML_INDEX = 0x00000812,
>> + * PML_ADDRESS = 0x0000200e,
>> + * VM_FUNCTION_CONTROL = 0x00002018,
>> + * EPTP_LIST_ADDRESS = 0x00002024,
>> + * VMREAD_BITMAP = 0x00002026,
>> + * VMWRITE_BITMAP = 0x00002028,
>> + *
>> + * TSC_MULTIPLIER = 0x00002032,
>> + * PLE_GAP = 0x00004020,
>> + * PLE_WINDOW = 0x00004022,
>> + * VMX_PREEMPTION_TIMER_VALUE = 0x0000482E,
>> + * GUEST_IA32_PERF_GLOBAL_CTRL = 0x00002808,
>> + * HOST_IA32_PERF_GLOBAL_CTRL = 0x00002c04,
>> + *
>> + * Currently unsupported in KVM:
>> + * GUEST_IA32_RTIT_CTL = 0x00002814,
>> + */
>> +#define EVMCS1_UNSUPPORTED_PINCTRL (PIN_BASED_POSTED_INTR | \
>> + PIN_BASED_VMX_PREEMPTION_TIMER)
>> +#define EVMCS1_UNSUPPORTED_2NDEXEC \
>> + (SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY | \
>> + SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES | \
>> + SECONDARY_EXEC_APIC_REGISTER_VIRT | \
>> + SECONDARY_EXEC_ENABLE_PML | \
>> + SECONDARY_EXEC_ENABLE_VMFUNC | \
>> + SECONDARY_EXEC_SHADOW_VMCS | \
>> + SECONDARY_EXEC_TSC_SCALING | \
>> + SECONDARY_EXEC_PAUSE_LOOP_EXITING)
>> +#define EVMCS1_UNSUPPORTED_VMEXIT_CTRL
>> (VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL)
>> +#define EVMCS1_UNSUPPORTED_VMENTRY_CTRL
>> (VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL)
>> +#define EVMCS1_UNSUPPORTED_VMFUNC (VMX_VMFUNC_EPTP_SWITCHING)
>> +
>> #if IS_ENABLED(CONFIG_HYPERV)
>> static bool __read_mostly enlightened_vmcs = true;
>> module_param(enlightened_vmcs, bool, 0444);
>> @@ -1278,69 +1328,12 @@ static void evmcs_load(u64 phys_addr)
>>
>> static void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf)
>> {
>> - /*
>> - * Enlightened VMCSv1 doesn't support these:
>> - *
>> - * POSTED_INTR_NV = 0x00000002,
>> - * GUEST_INTR_STATUS = 0x00000810,
>> - * APIC_ACCESS_ADDR = 0x00002014,
>> - * POSTED_INTR_DESC_ADDR = 0x00002016,
>> - * EOI_EXIT_BITMAP0 = 0x0000201c,
>> - * EOI_EXIT_BITMAP1 = 0x0000201e,
>> - * EOI_EXIT_BITMAP2 = 0x00002020,
>> - * EOI_EXIT_BITMAP3 = 0x00002022,
>> - */
>> - vmcs_conf->pin_based_exec_ctrl &= ~PIN_BASED_POSTED_INTR;
>> - vmcs_conf->cpu_based_2nd_exec_ctrl &=
>> - ~SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY;
>> - vmcs_conf->cpu_based_2nd_exec_ctrl &=
>> - ~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
>> - vmcs_conf->cpu_based_2nd_exec_ctrl &=
>> - ~SECONDARY_EXEC_APIC_REGISTER_VIRT;
>> -
>> - /*
>> - * GUEST_PML_INDEX = 0x00000812,
>> - * PML_ADDRESS = 0x0000200e,
>> - */
>> - vmcs_conf->cpu_based_2nd_exec_ctrl &= ~SECONDARY_EXEC_ENABLE_PML;
>> + vmcs_conf->pin_based_exec_ctrl &= ~EVMCS1_UNSUPPORTED_PINCTRL;
>> + vmcs_conf->cpu_based_2nd_exec_ctrl &= ~EVMCS1_UNSUPPORTED_2NDEXEC;
>>
>> - /* VM_FUNCTION_CONTROL = 0x00002018, */
>> - vmcs_conf->cpu_based_2nd_exec_ctrl &=
>> ~SECONDARY_EXEC_ENABLE_VMFUNC;
>> + vmcs_conf->vmexit_ctrl &= ~EVMCS1_UNSUPPORTED_VMEXIT_CTRL;
>> + vmcs_conf->vmentry_ctrl &= ~EVMCS1_UNSUPPORTED_VMENTRY_CTRL;
>>
>> - /*
>> - * EPTP_LIST_ADDRESS = 0x00002024,
>> - * VMREAD_BITMAP = 0x00002026,
>> - * VMWRITE_BITMAP = 0x00002028,
>> - */
>> - vmcs_conf->cpu_based_2nd_exec_ctrl &= ~SECONDARY_EXEC_SHADOW_VMCS;
>> -
>> - /*
>> - * TSC_MULTIPLIER = 0x00002032,
>> - */
>> - vmcs_conf->cpu_based_2nd_exec_ctrl &= ~SECONDARY_EXEC_TSC_SCALING;
>> -
>> - /*
>> - * PLE_GAP = 0x00004020,
>> - * PLE_WINDOW = 0x00004022,
>> - */
>> - vmcs_conf->cpu_based_2nd_exec_ctrl &=
>> ~SECONDARY_EXEC_PAUSE_LOOP_EXITING;
>> -
>> - /*
>> - * VMX_PREEMPTION_TIMER_VALUE = 0x0000482E,
>> - */
>> - vmcs_conf->pin_based_exec_ctrl &= ~PIN_BASED_VMX_PREEMPTION_TIMER;
>> -
>> - /*
>> - * GUEST_IA32_PERF_GLOBAL_CTRL = 0x00002808,
>> - * HOST_IA32_PERF_GLOBAL_CTRL = 0x00002c04,
>> - */
>> - vmcs_conf->vmexit_ctrl &= ~VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL;
>> - vmcs_conf->vmentry_ctrl &= ~VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL;
>> -
>> - /*
>> - * Currently unsupported in KVM:
>> - * GUEST_IA32_RTIT_CTL = 0x00002814,
>> - */
>
> The creation of the EVMCS1_UNSUPPORTED_* macros and the refactor to evmcs_sanitize_exec_ctrls()
> should be done in a separate patch in this series before this one.
>

Sure, will do!

>> }
>> #else /* !IS_ENABLED(CONFIG_HYPERV) */
>> static inline void evmcs_write64(unsigned long field, u64 value) {}
>> @@ -1354,6 +1347,27 @@ static inline void
>> evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf) {}
>> static inline void evmcs_touch_msr_bitmap(void) {}
>> #endif /* IS_ENABLED(CONFIG_HYPERV) */
>>
>> +static int nested_enable_evmcs(struct kvm_vcpu *vcpu,
>> + uint16_t *vmcs_version)
>> +{
>> + struct vcpu_vmx *vmx = to_vmx(vcpu);
>> +
>> + /* We don't support disabling the feature for simplicity. */
>> + if (vmx->nested.enlightened_vmcs_enabled)
>> + return 0;
>> +
>> + vmx->nested.enlightened_vmcs_enabled = true;
>> + *vmcs_version = (KVM_EVMCS_VERSION << 8) | 1;
>
> Please add a comment here explaining the "<< 8) | 1" part.
>

Got it.

>> +
>> + vmx->nested.msrs.pinbased_ctls_high &= ~EVMCS1_UNSUPPORTED_PINCTRL;
>> + vmx->nested.msrs.entry_ctls_high &=
>> ~EVMCS1_UNSUPPORTED_VMENTRY_CTRL;
>> + vmx->nested.msrs.exit_ctls_high &= ~EVMCS1_UNSUPPORTED_VMEXIT_CTRL;
>> + vmx->nested.msrs.secondary_ctls_high &=
>> ~EVMCS1_UNSUPPORTED_2NDEXEC;
>> + vmx->nested.msrs.vmfunc_controls &= ~EVMCS1_UNSUPPORTED_VMFUNC;
>> +
>> + return 0;
>> +}
>> +
>> static inline bool is_exception_n(u32 intr_info, u8 vector)
>> {
>> return (intr_info & (INTR_INFO_INTR_TYPE_MASK |
>> INTR_INFO_VECTOR_MASK |
>> @@ -13039,6 +13053,8 @@ static struct kvm_x86_ops vmx_x86_ops
>> __ro_after_init = {
>> .pre_enter_smm = vmx_pre_enter_smm,
>> .pre_leave_smm = vmx_pre_leave_smm,
>> .enable_smi_window = enable_smi_window,
>> +
>> + .nested_enable_evmcs = nested_enable_evmcs,
>> };
>>
>> static int __init vmx_init(void)
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index a57766b940a5..51488019dec2 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -2873,6 +2873,7 @@ int kvm_vm_ioctl_check_extension(struct kvm
>> *kvm, long ext)
>> case KVM_CAP_HYPERV_VP_INDEX:
>> case KVM_CAP_HYPERV_EVENTFD:
>> case KVM_CAP_HYPERV_TLBFLUSH:
>> + case KVM_CAP_HYPERV_ENLIGHTENED_VMCS:
>> case KVM_CAP_PCI_SEGMENT:
>> case KVM_CAP_DEBUGREGS:
>> case KVM_CAP_X86_ROBUST_SINGLESTEP:
>> @@ -3650,6 +3651,10 @@ static int kvm_set_guest_paused(struct kvm_vcpu
>> *vcpu)
>> static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
>> struct kvm_enable_cap *cap)
>> {
>> + int r;
>> + uint16_t vmcs_version;
>> + void __user *user_ptr;
>> +
>> if (cap->flags)
>> return -EINVAL;
>>
>> @@ -3662,6 +3667,16 @@ static int kvm_vcpu_ioctl_enable_cap(struct
>> kvm_vcpu *vcpu,
>> return -EINVAL;
>> return kvm_hv_activate_synic(vcpu, cap->cap ==
>> KVM_CAP_HYPERV_SYNIC2);
>> + case KVM_CAP_HYPERV_ENLIGHTENED_VMCS:
>> + r = kvm_x86_ops->nested_enable_evmcs(vcpu, &vmcs_version);
>> + if (!r) {
>> + user_ptr = (void __user *)(uintptr_t)cap->args[0];
>> + if (copy_to_user(user_ptr, &vmcs_version,
>> + sizeof(vmcs_version)))
>> + r = -EFAULT;
>> + }
>> + return r;
>> +
>> default:
>> return -EINVAL;
>> }
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index b6270a3b38e9..5c4b79c1af19 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -949,6 +949,7 @@ struct kvm_ppc_resize_hpt {
>> #define KVM_CAP_GET_MSR_FEATURES 153
>> #define KVM_CAP_HYPERV_EVENTFD 154
>> #define KVM_CAP_HYPERV_TLBFLUSH 155
>> +#define KVM_CAP_HYPERV_ENLIGHTENED_VMCS 156
>>
>> #ifdef KVM_CAP_IRQ_ROUTING
>>
>> --
>> 2.14.4
>
> Besides above comments,
> Reviewed-By: Liran Alon <liran.alon@xxxxxxxxxx>

Thank you for reviewing the series!

--
Vitaly

Next message: Ilpo Järvinen: "Re: [RFC PATCH RESEND] tcp: avoid F-RTO if SACK and timestamps are disabled"
Previous message: Vitaly Kuznetsov: "Re: [PATCH 3/5] KVM: nVMX: add enlightened VMCS state"
In reply to: Liran Alon: "Re: [PATCH 2/5] KVM: nVMX: add KVM_CAP_HYPERV_ENLIGHTENED_VMCS capability"
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