linux-kernel - [PATCH v2 12/31] KVM: x86: hyper-v: Introduce kvm_hv_is_tlb_flush

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Date:   Thu,  7 Apr 2022 17:56:26 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Siddharth Chandrasekaran <sidcha@...zon.de>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 12/31] KVM: x86: hyper-v: Introduce kvm_hv_is_tlb_flush_hcall()

The newly introduced helper checks whether vCPU is performing a
Hyper-V TLB flush hypercall. This is required to filter out Direct TLB
flush hypercalls from L2 for processing.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/hyperv.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
index 448877b478ef..3687e1e61e0d 100644
--- a/arch/x86/kvm/hyperv.h
+++ b/arch/x86/kvm/hyperv.h
@@ -168,6 +168,30 @@ static inline void kvm_hv_vcpu_empty_flush_tlb(struct kvm_vcpu *vcpu)
 	tlb_flush_ring = kvm_hv_get_tlb_flush_ring(vcpu);
 	tlb_flush_ring->read_idx = tlb_flush_ring->write_idx;
 }
+
+static inline bool kvm_hv_is_tlb_flush_hcall(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
+	u16 code;
+
+	if (!hv_vcpu)
+		return false;
+
+#ifdef CONFIG_X86_64
+	if (is_64_bit_hypercall(vcpu)) {
+		code = kvm_rcx_read(vcpu) & 0xffff;
+	} else
+#endif
+	{
+		code = kvm_rax_read(vcpu) & 0xffff;
+	}
+
+	return (code == HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE ||
+		code == HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST ||
+		code == HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX ||
+		code == HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX);
+}
+
 void kvm_hv_vcpu_flush_tlb(struct kvm_vcpu *vcpu);
 
 
-- 
2.35.1