KVM: selftests: Hyper-V PV TLB flush selftest

Introduce a selftest for Hyper-V PV TLB flush hypercalls
(HvFlushVirtualAddressSpace/HvFlushVirtualAddressSpaceEx,
HvFlushVirtualAddressList/HvFlushVirtualAddressListEx).

The test creates one 'sender' vCPU and two 'worker' vCPU which do busy
loop reading from a certain GVA checking the observed value. Sender
vCPU swaos the data page with another page filled with a different value.
The expectation for workers is also altered. Without TLB flush on worker
vCPUs, they may continue to observe old value. To guard against accidental
TLB flushes for worker vCPUs the test is repeated 100 times.

Hyper-V TLB flush hypercalls are tested in both 'normal' and 'XMM
fast' modes.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-38-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/.gitignore

@@ -27,6 +27,7 @@
 /x86_64/hyperv_features
 /x86_64/hyperv_ipi
 /x86_64/hyperv_svm_test
+/x86_64/hyperv_tlb_flush
 /x86_64/max_vcpuid_cap_test
 /x86_64/mmio_warning_test
 /x86_64/monitor_mwait_test

tools/testing/selftests/kvm/Makefile

@@ -89,6 +89,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/hyperv_cpuid
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_features
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_ipi
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_svm_test
+TEST_GEN_PROGS_x86_64 += x86_64/hyperv_tlb_flush
 TEST_GEN_PROGS_x86_64 += x86_64/kvm_clock_test
 TEST_GEN_PROGS_x86_64 += x86_64/kvm_pv_test
 TEST_GEN_PROGS_x86_64 += x86_64/mmio_warning_test

tools/testing/selftests/kvm/include/x86_64/hyperv.h

@@ -187,6 +187,7 @@
 /* hypercall options */
 #define HV_HYPERCALL_FAST_BIT		BIT(16)
 #define HV_HYPERCALL_VARHEAD_OFFSET	17
+#define HV_HYPERCALL_REP_COMP_OFFSET	32
 
 /*
  * Issue a Hyper-V hypercall. Returns exception vector raised or 0, 'hv_status'