[PATCH RFC 12/19] KVM: x86: hyper-v: Introduce kvm_hv_is_tlb_flush_hcall()

[Vitaly Kuznetsov]

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@xxxxxxxxxx>
---
 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 137f906eb8c3..0c0877a6aa74 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