linux-kernel - [PATCH 3/5] KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS

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Date:   Mon,  2 Apr 2018 18:10:57 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org
Cc:     x86@...nel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Roman Kagan <rkagan@...tuozzo.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "Michael Kelley (EOSG)" <Michael.H.Kelley@...rosoft.com>,
        Mohammed Gamal <mmorsy@...hat.com>,
        Cathy Avery <cavery@...hat.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 3/5] KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE} implementation

Implement HvFlushVirtualAddress{List,Space} hypercalls in a simplistic way:
do full TLB flush with KVM_REQ_TLB_FLUSH and rely on kvm_vcpu_kick()
kicking only vCPUs which are currently IN_GUEST_MODE.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/hyperv.c | 54 ++++++++++++++++++++++++++++++++++++++++++++-------
 arch/x86/kvm/trace.h  | 24 +++++++++++++++++++++++
 2 files changed, 71 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 3cb3bb68db7e..aa866994366d 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1242,6 +1242,49 @@ int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
 		return kvm_hv_get_msr(vcpu, msr, pdata);
 }
 
+static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
+			    u16 rep_cnt)
+{
+	struct kvm *kvm = current_vcpu->kvm;
+	struct hv_tlb_flush flush;
+	struct kvm_vcpu *vcpu;
+	int i;
+
+	if (unlikely(kvm_read_guest(kvm, ingpa, &flush, sizeof(flush))))
+		return HV_STATUS_INVALID_HYPERCALL_INPUT;
+
+	trace_kvm_hv_flush_tlb(flush.processor_mask, flush.address_space,
+			       flush.flags);
+
+	kvm_for_each_vcpu(i, vcpu, kvm) {
+		struct kvm_vcpu_hv *hv = &vcpu->arch.hyperv;
+
+		if (!(flush.flags & HV_FLUSH_ALL_PROCESSORS) &&
+		    !(flush.processor_mask & BIT_ULL(hv->vp_index)))
+			continue;
+
+		/*
+		 * vcpu->arch.cr3 may not be up-to-date for running vCPUs so we
+		 * can't analyze it here, flush TLB regardless of the specified
+		 * address space.
+		 */
+		kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
+
+		/*
+		 * It is very unlikely but possible that we're doing an extra
+		 * kick here (e.g. if the vCPU has just entered the guest and
+		 * has its TLB flushed).
+		 */
+		if (vcpu != current_vcpu)
+			kvm_vcpu_kick(vcpu);
+	}
+
+	/* We always do full TLB flush, set rep_done = rep_cnt. */
+	return (u64)HV_STATUS_SUCCESS |
+		((u64)rep_cnt << HV_HYPERCALL_REP_START_OFFSET) |
+		((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;
@@ -1345,12 +1388,6 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 
 	trace_kvm_hv_hypercall(code, fast, rep_cnt, rep_idx, ingpa, outgpa);
 
-	/* Hypercall continuation is not supported yet */
-	if (rep_cnt || rep_idx) {
-		ret = HV_STATUS_INVALID_HYPERCALL_CODE;
-		goto set_result;
-	}
-
 	switch (code) {
 	case HVCALL_NOTIFY_LONG_SPIN_WAIT:
 		kvm_vcpu_on_spin(vcpu, true);
@@ -1374,12 +1411,15 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 		vcpu->arch.complete_userspace_io =
 				kvm_hv_hypercall_complete_userspace;
 		return 0;
+	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
+	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
+		ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt);
+		break;
 	default:
 		ret = HV_STATUS_INVALID_HYPERCALL_CODE;
 		break;
 	}
 
-set_result:
 	kvm_hv_hypercall_set_result(vcpu, ret);
 	return 1;
 }
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 9807c314c478..47a4fd758743 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -1367,6 +1367,30 @@ TRACE_EVENT(kvm_hv_timer_state,
 			__entry->vcpu_id,
 			__entry->hv_timer_in_use)
 );
+
+/*
+ * Tracepoint for kvm_hv_flush_tlb.
+ */
+TRACE_EVENT(kvm_hv_flush_tlb,
+	TP_PROTO(u64 processor_mask, u64 address_space, u64 flags),
+	TP_ARGS(processor_mask, address_space, flags),
+
+	TP_STRUCT__entry(
+		__field(u64, processor_mask)
+		__field(u64, address_space)
+		__field(u64, flags)
+	),
+
+	TP_fast_assign(
+		__entry->processor_mask = processor_mask;
+		__entry->address_space = address_space;
+		__entry->flags = flags;
+	),
+
+	TP_printk("processor_mask 0x%llx address_space 0x%llx flags 0x%llx",
+		  __entry->processor_mask, __entry->address_space,
+		  __entry->flags)
+);
 #endif /* _TRACE_KVM_H */
 
 #undef TRACE_INCLUDE_PATH
-- 
2.14.3