Re: [PATCH v3 5/6] KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}_EX implementation

2018-05-10 Thread Radim Krčmář
2018-04-16 13:08+0200, Vitaly Kuznetsov:
> Implement HvFlushVirtualAddress{List,Space}Ex hypercalls in a simplistic
> way: do full TLB flush with KVM_REQ_TLB_FLUSH and kick vCPUs which are
> currently IN_GUEST_MODE.
> 
> Signed-off-by: Vitaly Kuznetsov 
> ---
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> @@ -1301,6 +1301,108 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu 
> *current_vcpu, u64 ingpa,
>   ((u64)rep_cnt << HV_HYPERCALL_REP_COMP_OFFSET);
>  }
>  
> +static __always_inline int get_sparse_bank_no(u64 valid_bank_mask, int 
> bank_no)
> +{
> + int i = 0, j;
> +
> + if (!(valid_bank_mask & BIT_ULL(bank_no)))
> + return -1;
> +
> + for (j = 0; j < bank_no; j++)
> + if (valid_bank_mask & BIT_ULL(j))
> + i++;
> +
> + return i;
> +}
> +
> +static __always_inline int load_bank_guest(struct kvm *kvm, u64 ingpa,
> +   int sparse_bank, u64 *bank_contents)
> +{
> + int offset;
> +
> + offset = offsetof(struct hv_tlb_flush_ex, hv_vp_set.bank_contents) +
> + sizeof(u64) * sparse_bank;
> +
> + if (unlikely(kvm_read_guest(kvm, ingpa + offset,
> + bank_contents, sizeof(u64
> + return 1;
> +
> + return 0;
> +}
> +
> +static int kvm_hv_flush_tlb_ex(struct kvm_vcpu *current_vcpu, u64 ingpa,
> +u16 rep_cnt)
> +{
> + struct kvm *kvm = current_vcpu->kvm;
> + struct kvm_vcpu_hv *hv_current = ¤t_vcpu->arch.hyperv;
> + struct hv_tlb_flush_ex flush;
> + struct kvm_vcpu *vcpu;
> + u64 bank_contents, valid_bank_mask;
> + int i, cpu, me, current_sparse_bank = -1;
> + u64 ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
> +
> + if (unlikely(kvm_read_guest(kvm, ingpa, &flush, sizeof(flush
> + return ret;
> +
> + valid_bank_mask = flush.hv_vp_set.valid_bank_mask;
> +
> + trace_kvm_hv_flush_tlb_ex(valid_bank_mask, flush.hv_vp_set.format,
> +   flush.address_space, flush.flags);
> +
> + cpumask_clear(&hv_current->tlb_lush);
> +
> + me = get_cpu();
> +
> + kvm_for_each_vcpu(i, vcpu, kvm) {
> + struct kvm_vcpu_hv *hv = &vcpu->arch.hyperv;
> + int bank = hv->vp_index / 64, sparse_bank;
> +
> + if (flush.hv_vp_set.format == HV_GENERIC_SET_SPARCE_4K) {
 ^
  typo in the define

> + /* Check is the bank of this vCPU is in sparse set */
> + sparse_bank = get_sparse_bank_no(valid_bank_mask, bank);
> + if (sparse_bank < 0)
> + continue;
> +
> + /*
> +  * Assume hv->vp_index is in ascending order and we can
> +  * optimize by not reloading bank contents for every
> +  * vCPU.
> +  */

Since sparse_bank is packed, we could compute how many bank_contents do
we need to load and do it with one kvm_read_guest() into a local array;
it would be faster even if hv->vp_index were in ascending order and
wouldn't take that much memory (up to 512 B).

> + if (sparse_bank != current_sparse_bank) {
> + if (load_bank_guest(kvm, ingpa, sparse_bank,
> + &bank_contents))
> + return ret;
> + current_sparse_bank = sparse_bank;
> + }


[PATCH v3 5/6] KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}_EX implementation

2018-04-16 Thread Vitaly Kuznetsov
Implement HvFlushVirtualAddress{List,Space}Ex hypercalls in a simplistic
way: do full TLB flush with KVM_REQ_TLB_FLUSH and kick vCPUs which are
currently IN_GUEST_MODE.

Signed-off-by: Vitaly Kuznetsov 
---
 arch/x86/kvm/hyperv.c | 116 ++
 arch/x86/kvm/trace.h  |  27 
 2 files changed, 143 insertions(+)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index fa26af1e8b7c..7028cd58d5f4 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1301,6 +1301,108 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu 
*current_vcpu, u64 ingpa,
((u64)rep_cnt << HV_HYPERCALL_REP_COMP_OFFSET);
 }
 
+static __always_inline int get_sparse_bank_no(u64 valid_bank_mask, int bank_no)
+{
+   int i = 0, j;
+
+   if (!(valid_bank_mask & BIT_ULL(bank_no)))
+   return -1;
+
+   for (j = 0; j < bank_no; j++)
+   if (valid_bank_mask & BIT_ULL(j))
+   i++;
+
+   return i;
+}
+
+static __always_inline int load_bank_guest(struct kvm *kvm, u64 ingpa,
+ int sparse_bank, u64 *bank_contents)
+{
+   int offset;
+
+   offset = offsetof(struct hv_tlb_flush_ex, hv_vp_set.bank_contents) +
+   sizeof(u64) * sparse_bank;
+
+   if (unlikely(kvm_read_guest(kvm, ingpa + offset,
+   bank_contents, sizeof(u64
+   return 1;
+
+   return 0;
+}
+
+static int kvm_hv_flush_tlb_ex(struct kvm_vcpu *current_vcpu, u64 ingpa,
+  u16 rep_cnt)
+{
+   struct kvm *kvm = current_vcpu->kvm;
+   struct kvm_vcpu_hv *hv_current = ¤t_vcpu->arch.hyperv;
+   struct hv_tlb_flush_ex flush;
+   struct kvm_vcpu *vcpu;
+   u64 bank_contents, valid_bank_mask;
+   int i, cpu, me, current_sparse_bank = -1;
+   u64 ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+
+   if (unlikely(kvm_read_guest(kvm, ingpa, &flush, sizeof(flush
+   return ret;
+
+   valid_bank_mask = flush.hv_vp_set.valid_bank_mask;
+
+   trace_kvm_hv_flush_tlb_ex(valid_bank_mask, flush.hv_vp_set.format,
+ flush.address_space, flush.flags);
+
+   cpumask_clear(&hv_current->tlb_lush);
+
+   me = get_cpu();
+
+   kvm_for_each_vcpu(i, vcpu, kvm) {
+   struct kvm_vcpu_hv *hv = &vcpu->arch.hyperv;
+   int bank = hv->vp_index / 64, sparse_bank;
+
+   if (flush.hv_vp_set.format == HV_GENERIC_SET_SPARCE_4K) {
+   /* Check is the bank of this vCPU is in sparse set */
+   sparse_bank = get_sparse_bank_no(valid_bank_mask, bank);
+   if (sparse_bank < 0)
+   continue;
+
+   /*
+* Assume hv->vp_index is in ascending order and we can
+* optimize by not reloading bank contents for every
+* vCPU.
+*/
+   if (sparse_bank != current_sparse_bank) {
+   if (load_bank_guest(kvm, ingpa, sparse_bank,
+   &bank_contents))
+   return ret;
+   current_sparse_bank = sparse_bank;
+   }
+
+   if (!(bank_contents & BIT_ULL(hv->vp_index % 64)))
+   continue;
+   }
+
+   kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
+
+   /*
+* It is possible that vCPU will migrate and we will kick wrong
+* CPU but vCPU's TLB will anyway be flushed upon migration as
+* we already made KVM_REQ_TLB_FLUSH request.
+*/
+   cpu = vcpu->cpu;
+   if (cpu != -1 && cpu != me && cpu_online(cpu) &&
+   kvm_arch_vcpu_should_kick(vcpu))
+   cpumask_set_cpu(cpu, &hv_current->tlb_lush);
+   }
+
+   if (!cpumask_empty(&hv_current->tlb_lush))
+   smp_call_function_many(&hv_current->tlb_lush, ack_flush,
+  NULL, true);
+
+   put_cpu();
+
+   /* We always do full TLB flush, set rep_done = rep_cnt. */
+   return (u64)HV_STATUS_SUCCESS |
+   ((u64)rep_cnt << HV_HYPERCALL_REP_COMP_OFFSET);
+}
+
 bool kvm_hv_hypercall_enabled(struct kvm *kvm)
 {
return READ_ONCE(kvm->arch.hyperv.hv_hypercall) & 
HV_X64_MSR_HYPERCALL_ENABLE;
@@ -1450,6 +1552,20 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
}
ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt);
break;
+   case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
+   if (unlikely(fast || !rep_cnt || rep_idx)) {
+   ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+   break;
+   }