Re: [PATCH v5 3/7] KVM: x86: hyper-v: Move the remote TLB flush logic out of vmx

[Paolo Bonzini <pbonzini@redhat.com>]

On 10/06/21 13:20, Vitaly Kuznetsov wrote:

>> +static inline void hv_track_root_tdp(struct kvm_vcpu *vcpu, hpa_t root_tdp)
>> +{
>> +	struct kvm_arch *kvm_arch = &vcpu->kvm->arch;
>> +
>> +	if (kvm_x86_ops.tlb_remote_flush == hv_remote_flush_tlb) {
>> +		spin_lock(&kvm_arch->hv_root_tdp_lock);
>> +		vcpu->arch.hv_root_tdp = root_tdp;
>> +		if (root_tdp != kvm_arch->hv_root_tdp)
>> +			kvm_arch->hv_root_tdp = INVALID_PAGE;
>> +		spin_unlock(&kvm_arch->hv_root_tdp_lock);
>> +	}
>> +}
>> +#else
>> +static inline void hv_track_root_tdp(struct kvm_vcpu *vcpu, hpa_t root_tdp)
>> +{
>> +}
>> +#endif
>> +#endif
> 
> Super-nitpick: I'd suggest adding /* __ARCH_X86_KVM_KVM_ONHYPERV_H__ */
> to the second '#endif' and /* IS_ENABLED(CONFIG_HYPERV) */ to '#else'
> and the first one: files/functions tend to grow and it becomes hard to
> see where the particular '#endif/#else' belongs.

Done, thanks.  I've also changed the #if to just "#ifdef CONFIG_HYPERV", 
since IS_ENABLED is only needed in C statements.

Paolo

>> +
>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>> index d000cddbd734..117fb88cd354 100644
>> --- a/arch/x86/kvm/vmx/vmx.c
>> +++ b/arch/x86/kvm/vmx/vmx.c
>> @@ -52,6 +52,7 @@
>>   #include "cpuid.h"
>>   #include "evmcs.h"
>>   #include "hyperv.h"
>> +#include "kvm_onhyperv.h"
>>   #include "irq.h"
>>   #include "kvm_cache_regs.h"
>>   #include "lapic.h"
>> @@ -474,86 +475,6 @@ static const u32 vmx_uret_msrs_list[] = {
>>   static bool __read_mostly enlightened_vmcs = true;
>>   module_param(enlightened_vmcs, bool, 0444);
>>   
>> -static int kvm_fill_hv_flush_list_func(struct hv_guest_mapping_flush_list *flush,
>> -		void *data)
>> -{
>> -	struct kvm_tlb_range *range = data;
>> -
>> -	return hyperv_fill_flush_guest_mapping_list(flush, range->start_gfn,
>> -			range->pages);
>> -}
>> -
>> -static inline int hv_remote_flush_root_ept(hpa_t root_ept,
>> -					   struct kvm_tlb_range *range)
>> -{
>> -	if (range)
>> -		return hyperv_flush_guest_mapping_range(root_ept,
>> -				kvm_fill_hv_flush_list_func, (void *)range);
>> -	else
>> -		return hyperv_flush_guest_mapping(root_ept);
>> -}
>> -
>> -static int hv_remote_flush_tlb_with_range(struct kvm *kvm,
>> -		struct kvm_tlb_range *range)
>> -{
>> -	struct kvm_vmx *kvm_vmx = to_kvm_vmx(kvm);
>> -	struct kvm_vcpu *vcpu;
>> -	int ret = 0, i, nr_unique_valid_roots;
>> -	hpa_t root;
>> -
>> -	spin_lock(&kvm_vmx->hv_root_ept_lock);
>> -
>> -	if (!VALID_PAGE(kvm_vmx->hv_root_ept)) {
>> -		nr_unique_valid_roots = 0;
>> -
>> -		/*
>> -		 * Flush all valid roots, and see if all vCPUs have converged
>> -		 * on a common root, in which case future flushes can skip the
>> -		 * loop and flush the common root.
>> -		 */
>> -		kvm_for_each_vcpu(i, vcpu, kvm) {
>> -			root = to_vmx(vcpu)->hv_root_ept;
>> -			if (!VALID_PAGE(root) || root == kvm_vmx->hv_root_ept)
>> -				continue;
>> -
>> -			/*
>> -			 * Set the tracked root to the first valid root.  Keep
>> -			 * this root for the entirety of the loop even if more
>> -			 * roots are encountered as a low effort optimization
>> -			 * to avoid flushing the same (first) root again.
>> -			 */
>> -			if (++nr_unique_valid_roots == 1)
>> -				kvm_vmx->hv_root_ept = root;
>> -
>> -			if (!ret)
>> -				ret = hv_remote_flush_root_ept(root, range);
>> -
>> -			/*
>> -			 * Stop processing roots if a failure occurred and
>> -			 * multiple valid roots have already been detected.
>> -			 */
>> -			if (ret && nr_unique_valid_roots > 1)
>> -				break;
>> -		}
>> -
>> -		/*
>> -		 * The optimized flush of a single root can't be used if there
>> -		 * are multiple valid roots (obviously).
>> -		 */
>> -		if (nr_unique_valid_roots > 1)
>> -			kvm_vmx->hv_root_ept = INVALID_PAGE;
>> -	} else {
>> -		ret = hv_remote_flush_root_ept(kvm_vmx->hv_root_ept, range);
>> -	}
>> -
>> -	spin_unlock(&kvm_vmx->hv_root_ept_lock);
>> -	return ret;
>> -}
>> -static int hv_remote_flush_tlb(struct kvm *kvm)
>> -{
>> -	return hv_remote_flush_tlb_with_range(kvm, NULL);
>> -}
>> -
>>   static int hv_enable_direct_tlbflush(struct kvm_vcpu *vcpu)
>>   {
>>   	struct hv_enlightened_vmcs *evmcs;
>> @@ -581,21 +502,6 @@ static int hv_enable_direct_tlbflush(struct kvm_vcpu *vcpu)
>>   
>>   #endif /* IS_ENABLED(CONFIG_HYPERV) */
>>   
>> -static void hv_track_root_ept(struct kvm_vcpu *vcpu, hpa_t root_ept)
>> -{
>> -#if IS_ENABLED(CONFIG_HYPERV)
>> -	struct kvm_vmx *kvm_vmx = to_kvm_vmx(vcpu->kvm);
>> -
>> -	if (kvm_x86_ops.tlb_remote_flush == hv_remote_flush_tlb) {
>> -		spin_lock(&kvm_vmx->hv_root_ept_lock);
>> -		to_vmx(vcpu)->hv_root_ept = root_ept;
>> -		if (root_ept != kvm_vmx->hv_root_ept)
>> -			kvm_vmx->hv_root_ept = INVALID_PAGE;
>> -		spin_unlock(&kvm_vmx->hv_root_ept_lock);
>> -	}
>> -#endif
>> -}
>> -
>>   /*
>>    * Comment's format: document - errata name - stepping - processor name.
>>    * Refer from
>> @@ -3202,7 +3108,7 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa,
>>   		eptp = construct_eptp(vcpu, root_hpa, root_level);
>>   		vmcs_write64(EPT_POINTER, eptp);
>>   
>> -		hv_track_root_ept(vcpu, root_hpa);
>> +		hv_track_root_tdp(vcpu, root_hpa);
>>   
>>   		if (!enable_unrestricted_guest && !is_paging(vcpu))
>>   			guest_cr3 = to_kvm_vmx(kvm)->ept_identity_map_addr;
>> @@ -6980,9 +6886,6 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
>>   	vmx->pi_desc.nv = POSTED_INTR_VECTOR;
>>   	vmx->pi_desc.sn = 1;
>>   
>> -#if IS_ENABLED(CONFIG_HYPERV)
>> -	vmx->hv_root_ept = INVALID_PAGE;
>> -#endif
>>   	return 0;
>>   
>>   free_vmcs:
>> @@ -6999,10 +6902,6 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
>>   
>>   static int vmx_vm_init(struct kvm *kvm)
>>   {
>> -#if IS_ENABLED(CONFIG_HYPERV)
>> -	spin_lock_init(&to_kvm_vmx(kvm)->hv_root_ept_lock);
>> -#endif
>> -
>>   	if (!ple_gap)
>>   		kvm->arch.pause_in_guest = true;
>>   
>> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
>> index 008cb87ff088..d1363e734a01 100644
>> --- a/arch/x86/kvm/vmx/vmx.h
>> +++ b/arch/x86/kvm/vmx/vmx.h
>> @@ -328,10 +328,6 @@ struct vcpu_vmx {
>>   	/* SGX Launch Control public key hash */
>>   	u64 msr_ia32_sgxlepubkeyhash[4];
>>   
>> -#if IS_ENABLED(CONFIG_HYPERV)
>> -	u64 hv_root_ept;
>> -#endif
>> -
>>   	struct pt_desc pt_desc;
>>   	struct lbr_desc lbr_desc;
>>   
>> @@ -349,11 +345,6 @@ struct kvm_vmx {
>>   	unsigned int tss_addr;
>>   	bool ept_identity_pagetable_done;
>>   	gpa_t ept_identity_map_addr;
>> -
>> -#if IS_ENABLED(CONFIG_HYPERV)
>> -	hpa_t hv_root_ept;
>> -	spinlock_t hv_root_ept_lock;
>> -#endif
>>   };
>>   
>>   bool nested_vmx_allowed(struct kvm_vcpu *vcpu);
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 6eda2834fc05..580f3c6c86f9 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -10279,6 +10279,10 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
>>   	vcpu->arch.pending_external_vector = -1;
>>   	vcpu->arch.preempted_in_kernel = false;
>>   
>> +#if IS_ENABLED(CONFIG_HYPERV)
>> +	vcpu->arch.hv_root_tdp = INVALID_PAGE;
>> +#endif
>> +
>>   	r = static_call(kvm_x86_vcpu_create)(vcpu);
>>   	if (r)
>>   		goto free_guest_fpu;
>> @@ -10662,6 +10666,11 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>>   
>>   	kvm->arch.guest_can_read_msr_platform_info = true;
>>   
>> +#if IS_ENABLED(CONFIG_HYPERV)
>> +	spin_lock_init(&kvm->arch.hv_root_tdp_lock);
>> +	kvm->arch.hv_root_tdp = INVALID_PAGE;
>> +#endif
>> +
>>   	INIT_DELAYED_WORK(&kvm->arch.kvmclock_update_work, kvmclock_update_fn);
>>   	INIT_DELAYED_WORK(&kvm->arch.kvmclock_sync_work, kvmclock_sync_fn);
>