Re: [PATCH 10/14] KVM: x86: Make Hyper-V emulation optional

[Vitaly Kuznetsov <vkuznets@redhat.com>]

Maxim Levitsky <mlevitsk@redhat.com> writes:

> On Wed, 2023-10-25 at 17:24 +0200, Vitaly Kuznetsov wrote:
>> Hyper-V emulation in KVM is a fairly big chunk and in some cases it may be
>> desirable to not compile it in to reduce module sizes as well as the attack
>> surface. Introduce CONFIG_KVM_HYPERV option to make it possible.
>> 
>> Note, there's room for further nVMX/nSVM code optimizations when
>> !CONFIG_KVM_HYPERV, this will be done in follow-up patches.
>> 
>> Reorganize Makefile a bit so all CONFIG_HYPERV and CONFIG_KVM_HYPERV files
>> are grouped together.
>> 
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>> ---
>>  arch/x86/include/asm/kvm_host.h |  4 +++
>>  arch/x86/kvm/Kconfig            | 14 ++++++++
>>  arch/x86/kvm/Makefile           | 23 ++++++------
>>  arch/x86/kvm/cpuid.c            |  6 ++++
>>  arch/x86/kvm/hyperv.h           | 30 ++++++++++++++--
>>  arch/x86/kvm/irq_comm.c         |  9 ++++-
>>  arch/x86/kvm/svm/hyperv.h       |  7 ++++
>>  arch/x86/kvm/vmx/hyperv.h       |  8 +++++
>>  arch/x86/kvm/vmx/nested.c       | 15 ++++++++
>>  arch/x86/kvm/x86.c              | 62 ++++++++++++++++++++++++---------
>>  10 files changed, 147 insertions(+), 31 deletions(-)
>> 
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index 7fb2810f4573..e5b881dda747 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -1095,6 +1095,7 @@ enum hv_tsc_page_status {
>>  	HV_TSC_PAGE_BROKEN,
>>  };
>>  
>> +#ifdef CONFIG_KVM_HYPERV
>>  /* Hyper-V emulation context */
>>  struct kvm_hv {
>>  	struct mutex hv_lock;
>> @@ -1127,6 +1128,7 @@ struct kvm_hv {
>>  
>>  	struct kvm_hv_syndbg hv_syndbg;
>>  };
>> +#endif
>>  
>>  struct msr_bitmap_range {
>>  	u32 flags;
>> @@ -1349,7 +1351,9 @@ struct kvm_arch {
>>  	/* reads protected by irq_srcu, writes by irq_lock */
>>  	struct hlist_head mask_notifier_list;
>>  
>> +#ifdef CONFIG_KVM_HYPERV
>>  	struct kvm_hv hyperv;
>> +#endif
>>  
>>  #ifdef CONFIG_KVM_XEN
>>  	struct kvm_xen xen;
>> diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
>> index 950c12868d30..93930cef9b3b 100644
>> --- a/arch/x86/kvm/Kconfig
>> +++ b/arch/x86/kvm/Kconfig
>> @@ -129,6 +129,20 @@ config KVM_SMM
>>  
>>  	  If unsure, say Y.
>>  
>> +config KVM_HYPERV
>> +	bool "Support for Microsoft Hyper-V emulation"
>> +	depends on KVM
>> +	default y
>> +	help
>> +	  Provides KVM support for emulating Microsoft Hyper-V.  This allows KVM
>> +	  to expose a subset of the paravirtualized interfaces defined in the
>> +	  Hyper-V Hypervisor Top-Level Functional Specification (TLFS):
>> +	  https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs
>> +	  These interfaces are required for the correct and performant functioning
>> +	  of Windows and Hyper-V guests on KVM.
> Looks very good.
>
>> +
>> +	  If unsure, say "Y".
>> +
>>  config KVM_XEN
>>  	bool "Support for Xen hypercall interface"
>>  	depends on KVM
>> diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
>> index 8ea872401cd6..b97b875ad75f 100644
>> --- a/arch/x86/kvm/Makefile
>> +++ b/arch/x86/kvm/Makefile
>> @@ -11,32 +11,33 @@ include $(srctree)/virt/kvm/Makefile.kvm
>>  
>>  kvm-y			+= x86.o emulate.o i8259.o irq.o lapic.o \
>>  			   i8254.o ioapic.o irq_comm.o cpuid.o pmu.o mtrr.o \
>> -			   hyperv.o debugfs.o mmu/mmu.o mmu/page_track.o \
>> +			   debugfs.o mmu/mmu.o mmu/page_track.o \
>>  			   mmu/spte.o
>>  
>> -ifdef CONFIG_HYPERV
>> -kvm-y			+= kvm_onhyperv.o
>> -endif
>> -
>>  kvm-$(CONFIG_X86_64) += mmu/tdp_iter.o mmu/tdp_mmu.o
>> +kvm-$(CONFIG_KVM_HYPERV) += hyperv.o
>>  kvm-$(CONFIG_KVM_XEN)	+= xen.o
>>  kvm-$(CONFIG_KVM_SMM)	+= smm.o
>>  
>>  kvm-intel-y		+= vmx/vmx.o vmx/vmenter.o vmx/pmu_intel.o vmx/vmcs12.o \
>> -			   vmx/hyperv.o vmx/hyperv_evmcs.o vmx/nested.o vmx/posted_intr.o
>> -kvm-intel-$(CONFIG_X86_SGX_KVM)	+= vmx/sgx.o
>> +			   vmx/nested.o vmx/posted_intr.o
>>  
>> -ifdef CONFIG_HYPERV
>> -kvm-intel-y		+= vmx/vmx_onhyperv.o
>> -endif
>> +kvm-intel-$(CONFIG_X86_SGX_KVM)	+= vmx/sgx.o
>>  
>>  kvm-amd-y		+= svm/svm.o svm/vmenter.o svm/pmu.o svm/nested.o svm/avic.o \
>> -			   svm/sev.o svm/hyperv.o
>> +			   svm/sev.o
>>  
>>  ifdef CONFIG_HYPERV
>> +kvm-y			+= kvm_onhyperv.o
>> +kvm-intel-y		+= vmx/vmx_onhyperv.o vmx/hyperv_evmcs.o
>>  kvm-amd-y		+= svm/svm_onhyperv.o
>>  endif
>>  
>> +ifdef CONFIG_KVM_HYPERV
>> +kvm-intel-y		+= vmx/hyperv.o vmx/hyperv_evmcs.o
>> +kvm-amd-y		+= svm/hyperv.o
>> +endif
>> +
>>  obj-$(CONFIG_KVM)	+= kvm.o
>>  obj-$(CONFIG_KVM_INTEL)	+= kvm-intel.o
>>  obj-$(CONFIG_KVM_AMD)	+= kvm-amd.o
>
> This also looks much better.
>
>> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
>> index 464b23ac5f93..da8e0873f63a 100644
>> --- a/arch/x86/kvm/cpuid.c
>> +++ b/arch/x86/kvm/cpuid.c
>> @@ -314,11 +314,15 @@ EXPORT_SYMBOL_GPL(kvm_update_cpuid_runtime);
>>  
>>  static bool kvm_cpuid_has_hyperv(struct kvm_cpuid_entry2 *entries, int nent)
>>  {
>> +#ifdef CONFIG_KVM_HYPERV
>>  	struct kvm_cpuid_entry2 *entry;
>>  
>>  	entry = cpuid_entry2_find(entries, nent, HYPERV_CPUID_INTERFACE,
>>  				  KVM_CPUID_INDEX_NOT_SIGNIFICANT);
>>  	return entry && entry->eax == HYPERV_CPUID_SIGNATURE_EAX;
>> +#else
>> +	return false;
>> +#endif
>>  }
>>  
>>  static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
>> @@ -433,11 +437,13 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
>>  		return 0;
>>  	}
>>  
>> +#ifdef CONFIG_KVM_HYPERV
>>  	if (kvm_cpuid_has_hyperv(e2, nent)) {
>>  		r = kvm_hv_vcpu_init(vcpu);
>>  		if (r)
>>  			return r;
>>  	}
>> +#endif
>>  
>>  	r = kvm_check_cpuid(vcpu, e2, nent);
>>  	if (r)
>> diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
>> index 75dcbe598fbc..5c5ec7015136 100644
>> --- a/arch/x86/kvm/hyperv.h
>> +++ b/arch/x86/kvm/hyperv.h
>> @@ -24,6 +24,8 @@
>>  #include <linux/kvm_host.h>
>>  #include "x86.h"
>>  
>> +#ifdef CONFIG_KVM_HYPERV
>> +
>>  /* "Hv#1" signature */
>>  #define HYPERV_CPUID_SIGNATURE_EAX 0x31237648
>>  
>> @@ -259,5 +261,29 @@ static inline void kvm_hv_nested_transtion_tlb_flush(struct kvm_vcpu *vcpu, bool
>>  }
>>  
>>  int kvm_hv_vcpu_flush_tlb(struct kvm_vcpu *vcpu);
>> -
>> -#endif
>> +#else /* CONFIG_KVM_HYPERV */
>> +static inline void kvm_hv_setup_tsc_page(struct kvm *kvm,
>> +					 struct pvclock_vcpu_time_info *hv_clock) {}
>> +static inline void kvm_hv_request_tsc_page_update(struct kvm *kvm) {}
>> +static inline void kvm_hv_init_vm(struct kvm *kvm) {}
>> +static inline void kvm_hv_destroy_vm(struct kvm *kvm) {}
>> +static inline int kvm_hv_vcpu_init(struct kvm_vcpu *vcpu) { return 0; }
>> +static inline void kvm_hv_vcpu_uninit(struct kvm_vcpu *vcpu) {}
>> +static inline bool kvm_hv_hypercall_enabled(struct kvm_vcpu *vcpu) { return false; }
>> +static inline int kvm_hv_hypercall(struct kvm_vcpu *vcpu) { return HV_STATUS_ACCESS_DENIED; }
>> +static inline void kvm_hv_vcpu_purge_flush_tlb(struct kvm_vcpu *vcpu) {}
>> +static inline void kvm_hv_free_pa_page(struct kvm *kvm) {}
>> +static inline bool kvm_hv_synic_has_vector(struct kvm_vcpu *vcpu, int vector) { return false; }
>> +static inline bool kvm_hv_synic_auto_eoi_set(struct kvm_vcpu *vcpu, int vector) { return false; }
>> +static inline void kvm_hv_synic_send_eoi(struct kvm_vcpu *vcpu, int vector) {}
>> +static inline bool kvm_hv_invtsc_suppressed(struct kvm_vcpu *vcpu) { return false; }
>> +static inline void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu, bool hyperv_enabled) {}
>> +static inline bool kvm_hv_has_stimer_pending(struct kvm_vcpu *vcpu) { return false; }
>> +static inline bool kvm_hv_is_tlb_flush_hcall(struct kvm_vcpu *vcpu) { return false; }
>> +static inline bool guest_hv_cpuid_has_l2_tlb_flush(struct kvm_vcpu *vcpu) { return false; }
>> +static inline int kvm_hv_verify_vp_assist(struct kvm_vcpu *vcpu) { return 0; }
>> +static inline u32 kvm_hv_get_vpindex(struct kvm_vcpu *vcpu) { return vcpu->vcpu_idx; }
>> +static inline void kvm_hv_nested_transtion_tlb_flush(struct kvm_vcpu *vcpu, bool tdp_enabled) {}
>> +#endif /* CONFIG_KVM_HYPERV */
>> +
>> +#endif /* __ARCH_X86_KVM_HYPERV_H__ */
>
>
>> diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
>> index 16d076a1b91a..68f3f6c26046 100644
>> --- a/arch/x86/kvm/irq_comm.c
>> +++ b/arch/x86/kvm/irq_comm.c
>> @@ -144,7 +144,7 @@ int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
>>  	return kvm_irq_delivery_to_apic(kvm, NULL, &irq, NULL);
>>  }
>>  
>> -
>> +#ifdef CONFIG_KVM_HYPERV
>>  static int kvm_hv_set_sint(struct kvm_kernel_irq_routing_entry *e,
>>  		    struct kvm *kvm, int irq_source_id, int level,
>>  		    bool line_status)
>> @@ -154,6 +154,7 @@ static int kvm_hv_set_sint(struct kvm_kernel_irq_routing_entry *e,
>>  
>>  	return kvm_hv_synic_set_irq(kvm, e->hv_sint.vcpu, e->hv_sint.sint);
>>  }
>> +#endif
>>  
>>  int kvm_arch_set_irq_inatomic(struct kvm_kernel_irq_routing_entry *e,
>>  			      struct kvm *kvm, int irq_source_id, int level,
>> @@ -163,9 +164,11 @@ int kvm_arch_set_irq_inatomic(struct kvm_kernel_irq_routing_entry *e,
>>  	int r;
>>  
>>  	switch (e->type) {
>> +#ifdef CONFIG_KVM_HYPERV
>>  	case KVM_IRQ_ROUTING_HV_SINT:
>>  		return kvm_hv_set_sint(e, kvm, irq_source_id, level,
>>  				       line_status);
>> +#endif
>>  
>>  	case KVM_IRQ_ROUTING_MSI:
>>  		if (kvm_msi_route_invalid(kvm, e))
>> @@ -314,11 +317,13 @@ int kvm_set_routing_entry(struct kvm *kvm,
>>  		if (kvm_msi_route_invalid(kvm, e))
>>  			return -EINVAL;
>>  		break;
>> +#ifdef CONFIG_KVM_HYPERV
>>  	case KVM_IRQ_ROUTING_HV_SINT:
>>  		e->set = kvm_hv_set_sint;
>>  		e->hv_sint.vcpu = ue->u.hv_sint.vcpu;
>>  		e->hv_sint.sint = ue->u.hv_sint.sint;
>>  		break;
>> +#endif
>>  #ifdef CONFIG_KVM_XEN
>>  	case KVM_IRQ_ROUTING_XEN_EVTCHN:
>>  		return kvm_xen_setup_evtchn(kvm, e, ue);
>> @@ -438,5 +443,7 @@ void kvm_scan_ioapic_routes(struct kvm_vcpu *vcpu,
>>  
>>  void kvm_arch_irq_routing_update(struct kvm *kvm)
>>  {
>> +#ifdef CONFIG_KVM_HYPERV
>>  	kvm_hv_irq_routing_update(kvm);
>> +#endif
>>  }
>> diff --git a/arch/x86/kvm/svm/hyperv.h b/arch/x86/kvm/svm/hyperv.h
>> index 02f4784b5d44..14eec2d9b6be 100644
>> --- a/arch/x86/kvm/svm/hyperv.h
>> +++ b/arch/x86/kvm/svm/hyperv.h
>> @@ -11,6 +11,7 @@
>>  #include "../hyperv.h"
>>  #include "svm.h"
>>  
>> +#ifdef CONFIG_KVM_HYPERV
>>  static inline void nested_svm_hv_update_vm_vp_ids(struct kvm_vcpu *vcpu)
>>  {
>>  	struct vcpu_svm *svm = to_svm(vcpu);
>> @@ -41,5 +42,11 @@ static inline bool nested_svm_l2_tlb_flush_enabled(struct kvm_vcpu *vcpu)
>>  }
>>  
>>  void svm_hv_inject_synthetic_vmexit_post_tlb_flush(struct kvm_vcpu *vcpu);
>> +#else /* CONFIG_KVM_HYPERV */
>> +static inline void nested_svm_hv_update_vm_vp_ids(struct kvm_vcpu *vcpu) {}
>> +static inline bool nested_svm_l2_tlb_flush_enabled(struct kvm_vcpu *vcpu) { return false; }
>> +static inline void svm_hv_inject_synthetic_vmexit_post_tlb_flush(struct kvm_vcpu *vcpu) {}
>> +#endif /* CONFIG_KVM_HYPERV */
>> +
>>  
>>  #endif /* __ARCH_X86_KVM_SVM_HYPERV_H__ */
>> diff --git a/arch/x86/kvm/vmx/hyperv.h b/arch/x86/kvm/vmx/hyperv.h
>> index d4ed99008518..933ef6cad5e6 100644
>> --- a/arch/x86/kvm/vmx/hyperv.h
>> +++ b/arch/x86/kvm/vmx/hyperv.h
>> @@ -20,6 +20,7 @@ enum nested_evmptrld_status {
>>  	EVMPTRLD_ERROR,
>>  };
>>  
>> +#ifdef CONFIG_KVM_HYPERV
>>  u64 nested_get_evmptr(struct kvm_vcpu *vcpu);
>>  uint16_t nested_get_evmcs_version(struct kvm_vcpu *vcpu);
>>  int nested_enable_evmcs(struct kvm_vcpu *vcpu,
>> @@ -28,5 +29,12 @@ void nested_evmcs_filter_control_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *
>>  int nested_evmcs_check_controls(struct vmcs12 *vmcs12);
>>  bool nested_evmcs_l2_tlb_flush_enabled(struct kvm_vcpu *vcpu);
>>  void vmx_hv_inject_synthetic_vmexit_post_tlb_flush(struct kvm_vcpu *vcpu);
>> +#else
>> +static inline u64 nested_get_evmptr(struct kvm_vcpu *vcpu) { return EVMPTR_INVALID; }
>> +static inline void nested_evmcs_filter_control_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata) {}
>> +static inline bool nested_evmcs_l2_tlb_flush_enabled(struct kvm_vcpu *vcpu) { return false; }
>> +static inline int nested_evmcs_check_controls(struct vmcs12 *vmcs12) { return 0; }
>> +#endif
>> +
>>  
>>  #endif /* __KVM_X86_VMX_HYPERV_H */
>> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
>> index 382c0746d069..d0d735974b2c 100644
>> --- a/arch/x86/kvm/vmx/nested.c
>> +++ b/arch/x86/kvm/vmx/nested.c
>> @@ -226,6 +226,7 @@ static void vmx_disable_shadow_vmcs(struct vcpu_vmx *vmx)
>>  
>>  static inline void nested_release_evmcs(struct kvm_vcpu *vcpu)
>>  {
>> +#ifdef CONFIG_KVM_HYPERV
>>  	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
>>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
>>  
>> @@ -241,6 +242,7 @@ static inline void nested_release_evmcs(struct kvm_vcpu *vcpu)
>>  		hv_vcpu->nested.vm_id = 0;
>>  		hv_vcpu->nested.vp_id = 0;
>>  	}
>> +#endif
>>  }
>>  
>>  static void vmx_sync_vmcs_host_state(struct vcpu_vmx *vmx,
>> @@ -1570,6 +1572,7 @@ static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx)
>>  	vmcs_load(vmx->loaded_vmcs->vmcs);
>>  }
>>  
>> +#ifdef CONFIG_KVM_HYPERV
>>  static void copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx, u32 hv_clean_fields)
>>  {
>>  	struct vmcs12 *vmcs12 = vmx->nested.cached_vmcs12;
>> @@ -2077,6 +2080,10 @@ static enum nested_evmptrld_status nested_vmx_handle_enlightened_vmptrld(
>>  
>>  	return EVMPTRLD_SUCCEEDED;
>>  }
>> +#else /* CONFIG_KVM_HYPERV */
>> +static inline void copy_enlightened_to_vmcs12(struct vcpu_vmx *vmx, u32 hv_clean_fields) {}
>> +static inline void copy_vmcs12_to_enlightened(struct vcpu_vmx *vmx) {}
>> +#endif /* CONFIG_KVM_HYPERV */
>>  
>>  void nested_sync_vmcs12_to_shadow(struct kvm_vcpu *vcpu)
>>  {
>> @@ -3155,6 +3162,7 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu)
>>  	return 0;
>>  }
>>  
>> +#ifdef CONFIG_KVM_HYPERV
>>  static bool nested_get_evmcs_page(struct kvm_vcpu *vcpu)
>>  {
>>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
>> @@ -3182,6 +3190,9 @@ static bool nested_get_evmcs_page(struct kvm_vcpu *vcpu)
>>  
>>  	return true;
>>  }
>> +#else
>> +static bool nested_get_evmcs_page(struct kvm_vcpu *vcpu) { return true; }
>> +#endif
>>  
>>  static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
>>  {
>> @@ -3552,11 +3563,13 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
>>  	if (!nested_vmx_check_permission(vcpu))
>>  		return 1;
>>  
>> +#ifdef CONFIG_KVM_HYPERV
>>  	evmptrld_status = nested_vmx_handle_enlightened_vmptrld(vcpu, launch);
>>  	if (evmptrld_status == EVMPTRLD_ERROR) {
>>  		kvm_queue_exception(vcpu, UD_VECTOR);
>>  		return 1;
>>  	}
>> +#endif
>>  
>>  	kvm_pmu_trigger_event(vcpu, PERF_COUNT_HW_BRANCH_INSTRUCTIONS);
>>  
>> @@ -7090,7 +7103,9 @@ struct kvm_x86_nested_ops vmx_nested_ops = {
>>  	.set_state = vmx_set_nested_state,
>>  	.get_nested_state_pages = vmx_get_nested_state_pages,
>>  	.write_log_dirty = nested_vmx_write_pml_buffer,
>> +#ifdef CONFIG_KVM_HYPERV
>>  	.enable_evmcs = nested_enable_evmcs,
>>  	.get_evmcs_version = nested_get_evmcs_version,
>>  	.hv_inject_synthetic_vmexit_post_tlb_flush = vmx_hv_inject_synthetic_vmexit_post_tlb_flush,
>> +#endif
>>  };
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index cc2524598368..8ef9898092cd 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -1504,6 +1504,8 @@ static unsigned num_msrs_to_save;
>>  static const u32 emulated_msrs_all[] = {
>>  	MSR_KVM_SYSTEM_TIME, MSR_KVM_WALL_CLOCK,
>>  	MSR_KVM_SYSTEM_TIME_NEW, MSR_KVM_WALL_CLOCK_NEW,
>> +
>> +#ifdef CONFIG_KVM_HYPERV
>>  	HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL,
>>  	HV_X64_MSR_TIME_REF_COUNT, HV_X64_MSR_REFERENCE_TSC,
>>  	HV_X64_MSR_TSC_FREQUENCY, HV_X64_MSR_APIC_FREQUENCY,
>> @@ -1521,6 +1523,7 @@ static const u32 emulated_msrs_all[] = {
>>  	HV_X64_MSR_SYNDBG_CONTROL, HV_X64_MSR_SYNDBG_STATUS,
>>  	HV_X64_MSR_SYNDBG_SEND_BUFFER, HV_X64_MSR_SYNDBG_RECV_BUFFER,
>>  	HV_X64_MSR_SYNDBG_PENDING_BUFFER,
>> +#endif
>>  
>>  	MSR_KVM_ASYNC_PF_EN, MSR_KVM_STEAL_TIME,
>>  	MSR_KVM_PV_EOI_EN, MSR_KVM_ASYNC_PF_INT, MSR_KVM_ASYNC_PF_ACK,
>> @@ -4022,6 +4025,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>>  		 * the need to ignore the workaround.
>>  		 */
>>  		break;
>> +#ifdef CONFIG_KVM_HYPERV
>>  	case HV_X64_MSR_GUEST_OS_ID ... HV_X64_MSR_SINT15:
>>  	case HV_X64_MSR_SYNDBG_CONTROL ... HV_X64_MSR_SYNDBG_PENDING_BUFFER:
>>  	case HV_X64_MSR_SYNDBG_OPTIONS:
>> @@ -4034,6 +4038,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>>  	case HV_X64_MSR_TSC_INVARIANT_CONTROL:
>>  		return kvm_hv_set_msr_common(vcpu, msr, data,
>>  					     msr_info->host_initiated);
>> +#endif
>>  	case MSR_IA32_BBL_CR_CTL3:
>>  		/* Drop writes to this legacy MSR -- see rdmsr
>>  		 * counterpart for further detail.
>> @@ -4378,6 +4383,7 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>>  		 */
>>  		msr_info->data = 0x20000000;
>>  		break;
>> +#ifdef CONFIG_KVM_HYPERV
>>  	case HV_X64_MSR_GUEST_OS_ID ... HV_X64_MSR_SINT15:
>>  	case HV_X64_MSR_SYNDBG_CONTROL ... HV_X64_MSR_SYNDBG_PENDING_BUFFER:
>>  	case HV_X64_MSR_SYNDBG_OPTIONS:
>> @@ -4391,6 +4397,7 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>>  		return kvm_hv_get_msr_common(vcpu,
>>  					     msr_info->index, &msr_info->data,
>>  					     msr_info->host_initiated);
>> +#endif
>>  	case MSR_IA32_BBL_CR_CTL3:
>>  		/* This legacy MSR exists but isn't fully documented in current
>>  		 * silicon.  It is however accessed by winxp in very narrow
>> @@ -4528,6 +4535,7 @@ static inline bool kvm_can_mwait_in_guest(void)
>>  		boot_cpu_has(X86_FEATURE_ARAT);
>>  }
>>  
>> +#ifdef CONFIG_KVM_HYPERV
>>  static int kvm_ioctl_get_supported_hv_cpuid(struct kvm_vcpu *vcpu,
>>  					    struct kvm_cpuid2 __user *cpuid_arg)
>>  {
>> @@ -4548,6 +4556,7 @@ static int kvm_ioctl_get_supported_hv_cpuid(struct kvm_vcpu *vcpu,
>>  
>>  	return 0;
>>  }
>> +#endif
>>  
>>  int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>  {
>> @@ -4574,9 +4583,11 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>  	case KVM_CAP_PIT_STATE2:
>>  	case KVM_CAP_SET_IDENTITY_MAP_ADDR:
>>  	case KVM_CAP_VCPU_EVENTS:
>> +#ifdef CONFIG_KVM_HYPERV
>>  	case KVM_CAP_HYPERV:
>>  	case KVM_CAP_HYPERV_VAPIC:
>>  	case KVM_CAP_HYPERV_SPIN:
>> +	case KVM_CAP_HYPERV_TIME:
>>  	case KVM_CAP_HYPERV_SYNIC:
>>  	case KVM_CAP_HYPERV_SYNIC2:
>>  	case KVM_CAP_HYPERV_VP_INDEX:
>> @@ -4586,6 +4597,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>  	case KVM_CAP_HYPERV_CPUID:
>>  	case KVM_CAP_HYPERV_ENFORCE_CPUID:
>>  	case KVM_CAP_SYS_HYPERV_CPUID:
>> +#endif
>>  	case KVM_CAP_PCI_SEGMENT:
>>  	case KVM_CAP_DEBUGREGS:
>>  	case KVM_CAP_X86_ROBUST_SINGLESTEP:
>> @@ -4595,7 +4607,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>  	case KVM_CAP_GET_TSC_KHZ:
>>  	case KVM_CAP_KVMCLOCK_CTRL:
>>  	case KVM_CAP_READONLY_MEM:
>> -	case KVM_CAP_HYPERV_TIME:
>>  	case KVM_CAP_IOAPIC_POLARITY_IGNORED:
>>  	case KVM_CAP_TSC_DEADLINE_TIMER:
>>  	case KVM_CAP_DISABLE_QUIRKS:
>> @@ -4705,12 +4716,14 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>  		r = kvm_x86_ops.nested_ops->get_state ?
>>  			kvm_x86_ops.nested_ops->get_state(NULL, NULL, 0) : 0;
>>  		break;
>> +#ifdef CONFIG_KVM_HYPERV
>>  	case KVM_CAP_HYPERV_DIRECT_TLBFLUSH:
>>  		r = kvm_x86_ops.enable_l2_tlb_flush != NULL;
>>  		break;
>>  	case KVM_CAP_HYPERV_ENLIGHTENED_VMCS:
>>  		r = kvm_x86_ops.nested_ops->enable_evmcs != NULL;
>>  		break;
>> +#endif
>>  	case KVM_CAP_SMALLER_MAXPHYADDR:
>>  		r = (int) allow_smaller_maxphyaddr;
>>  		break;
>> @@ -4872,9 +4885,11 @@ long kvm_arch_dev_ioctl(struct file *filp,
>>  	case KVM_GET_MSRS:
>>  		r = msr_io(NULL, argp, do_get_msr_feature, 1);
>>  		break;
>> +#ifdef CONFIG_KVM_HYPERV
>>  	case KVM_GET_SUPPORTED_HV_CPUID:
>>  		r = kvm_ioctl_get_supported_hv_cpuid(NULL, argp);
>>  		break;
>> +#endif
>>  	case KVM_GET_DEVICE_ATTR: {
>>  		struct kvm_device_attr attr;
>>  		r = -EFAULT;
>> @@ -5700,14 +5715,11 @@ static int kvm_vcpu_ioctl_device_attr(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;
>>  
>>  	switch (cap->cap) {
>> +#ifdef CONFIG_KVM_HYPERV
>>  	case KVM_CAP_HYPERV_SYNIC2:
>>  		if (cap->args[0])
>>  			return -EINVAL;
>> @@ -5719,16 +5731,22 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
>>  		return kvm_hv_activate_synic(vcpu, cap->cap ==
>>  					     KVM_CAP_HYPERV_SYNIC2);
>>  	case KVM_CAP_HYPERV_ENLIGHTENED_VMCS:
>> -		if (!kvm_x86_ops.nested_ops->enable_evmcs)
>> -			return -ENOTTY;
>> -		r = kvm_x86_ops.nested_ops->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;
>> +		{
>> +			int r;
>> +			uint16_t vmcs_version;
>> +			void __user *user_ptr;
>> +
>> +			if (!kvm_x86_ops.nested_ops->enable_evmcs)
>> +				return -ENOTTY;
>> +			r = kvm_x86_ops.nested_ops->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;
>>  		}
>> -		return r;
>
> Minor nitpick: Unless I missed something the above is just refactoring. Can this be split
> into a separate patch?

Yea, it's even less than refactoring: basically, we just need to avoid
"unused variable" warning when !CONFIG_KVM_HYPERV so we need to declare
'vmcs_version' and 'user_ptr' locally. This can certainly be done in a
separate patch but without CONFIG_KVM_HYPERV it would look like a
no-op so I'm on the fence.

>
>
>>  	case KVM_CAP_HYPERV_DIRECT_TLBFLUSH:
>>  		if (!kvm_x86_ops.enable_l2_tlb_flush)
>>  			return -ENOTTY;
>> @@ -5737,6 +5755,7 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
>>  
>>  	case KVM_CAP_HYPERV_ENFORCE_CPUID:
>>  		return kvm_hv_set_enforce_cpuid(vcpu, cap->args[0]);
>> +#endif
>>  
>>  	case KVM_CAP_ENFORCE_PV_FEATURE_CPUID:
>>  		vcpu->arch.pv_cpuid.enforce = cap->args[0];
>> @@ -6129,9 +6148,11 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
>>  		srcu_read_unlock(&vcpu->kvm->srcu, idx);
>>  		break;
>>  	}
>> +#ifdef CONFIG_KVM_HYPERV
>>  	case KVM_GET_SUPPORTED_HV_CPUID:
>>  		r = kvm_ioctl_get_supported_hv_cpuid(vcpu, argp);
>>  		break;
>> +#endif
>>  #ifdef CONFIG_KVM_XEN
>>  	case KVM_XEN_VCPU_GET_ATTR: {
>>  		struct kvm_xen_vcpu_attr xva;
>> @@ -7189,6 +7210,7 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
>>  		r = static_call(kvm_x86_mem_enc_unregister_region)(kvm, &region);
>>  		break;
>>  	}
>> +#ifdef CONFIG_KVM_HYPERV
>>  	case KVM_HYPERV_EVENTFD: {
>>  		struct kvm_hyperv_eventfd hvevfd;
>>  
>> @@ -7198,6 +7220,7 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
>>  		r = kvm_vm_ioctl_hv_eventfd(kvm, &hvevfd);
>>  		break;
>>  	}
>> +#endif
>>  	case KVM_SET_PMU_EVENT_FILTER:
>>  		r = kvm_vm_ioctl_set_pmu_event_filter(kvm, argp);
>>  		break;
>> @@ -10576,19 +10599,20 @@ static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)
>>  
>>  static void vcpu_load_eoi_exitmap(struct kvm_vcpu *vcpu)
>>  {
>> -	u64 eoi_exit_bitmap[4];
>> -
>>  	if (!kvm_apic_hw_enabled(vcpu->arch.apic))
>>  		return;
>>  
>> +#ifdef CONFIG_KVM_HYPERV
>>  	if (to_hv_vcpu(vcpu)) {
>> +		u64 eoi_exit_bitmap[4];
>> +
>>  		bitmap_or((ulong *)eoi_exit_bitmap,
>>  			  vcpu->arch.ioapic_handled_vectors,
>>  			  to_hv_synic(vcpu)->vec_bitmap, 256);
>>  		static_call_cond(kvm_x86_load_eoi_exitmap)(vcpu, eoi_exit_bitmap);
>>  		return;
>>  	}
>> -
>> +#endif
>
> Same here.
>

Yep, same story: 'eoi_exit_bitmap' is only used when CONFIG_KVM_HYPERV
so we need to move it under #ifdef. I hope it's OK to keep it here as
the change is really tiny and helps us to avoid second #ifdef.

>>  	static_call_cond(kvm_x86_load_eoi_exitmap)(
>>  		vcpu, (u64 *)vcpu->arch.ioapic_handled_vectors);
>>  }
>> @@ -10679,9 +10703,11 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>>  		 * the flushes are considered "remote" and not "local" because
>>  		 * the requests can be initiated from other vCPUs.
>>  		 */
>> +#ifdef CONFIG_KVM_HYPERV
>>  		if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu) &&
>>  		    kvm_hv_vcpu_flush_tlb(vcpu))
>>  			kvm_vcpu_flush_tlb_guest(vcpu);
>> +#endif
>>  
>>  		if (kvm_check_request(KVM_REQ_REPORT_TPR_ACCESS, vcpu)) {
>>  			vcpu->run->exit_reason = KVM_EXIT_TPR_ACCESS;
>> @@ -10734,6 +10760,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>>  			vcpu_load_eoi_exitmap(vcpu);
>>  		if (kvm_check_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu))
>>  			kvm_vcpu_reload_apic_access_page(vcpu);
>> +#ifdef CONFIG_KVM_HYPERV
>>  		if (kvm_check_request(KVM_REQ_HV_CRASH, vcpu)) {
>>  			vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
>>  			vcpu->run->system_event.type = KVM_SYSTEM_EVENT_CRASH;
>> @@ -10764,6 +10791,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>>  		 */
>>  		if (kvm_check_request(KVM_REQ_HV_STIMER, vcpu))
>>  			kvm_hv_process_stimers(vcpu);
>> +#endif
>>  		if (kvm_check_request(KVM_REQ_APICV_UPDATE, vcpu))
>>  			kvm_vcpu_update_apicv(vcpu);
>>  		if (kvm_check_request(KVM_REQ_APF_READY, vcpu))
>
> Besides nitpicks,
>
> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
>

Thanks!

>
> Best regards,
> 	Maxim Levitsky
>
>

-- 
Vitaly