[PATCH v2 6/6] KVM: selftests: Test Hyper-V extended hypercall exit to userspace

[Vipin Sharma]

Hyper-V extended hypercalls by default exit to userspace. Verify
userspace gets the call, update the result and then verify in guest
correct result is received.

Signed-off-by: Vipin Sharma <vipinsh@xxxxxxxxxx>
---
 tools/testing/selftests/kvm/.gitignore        |  1 +
 tools/testing/selftests/kvm/Makefile          |  1 +
 .../selftests/kvm/include/x86_64/processor.h  |  3 +
 .../kvm/x86_64/hyperv_extended_hypercalls.c   | 94 +++++++++++++++++++
 4 files changed, 99 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/x86_64/hyperv_extended_hypercalls.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 082855d94c72..b17874697d74 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -24,6 +24,7 @@
 /x86_64/hyperv_clock
 /x86_64/hyperv_cpuid
 /x86_64/hyperv_evmcs
+/x86_64/hyperv_extended_hypercalls
 /x86_64/hyperv_features
 /x86_64/hyperv_ipi
 /x86_64/hyperv_svm_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 2275ba861e0e..a0e12f5d9835 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -87,6 +87,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/fix_hypercall_test
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_clock
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_cpuid
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_evmcs
+TEST_GEN_PROGS_x86_64 += x86_64/hyperv_extended_hypercalls
 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
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 5d310abe6c3f..f167396b887b 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -168,6 +168,9 @@ struct kvm_x86_cpu_feature {
 #define X86_FEATURE_KVM_HC_MAP_GPA_RANGE	KVM_X86_CPU_FEATURE(0x40000001, 0, EAX, 16)
 #define X86_FEATURE_KVM_MIGRATION_CONTROL	KVM_X86_CPU_FEATURE(0x40000001, 0, EAX, 17)
 
+/* Hyper-V defined paravirt features */
+#define X86_FEATURE_HYPERV_EXTENDED_HYPERCALLS	KVM_X86_CPU_FEATURE(0x40000003, 0, EBX, 20)
+
 /*
  * Same idea as X86_FEATURE_XXX, but X86_PROPERTY_XXX retrieves a multi-bit
  * value/property as opposed to a single-bit feature.  Again, pack the info
diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_extended_hypercalls.c b/tools/testing/selftests/kvm/x86_64/hyperv_extended_hypercalls.c
new file mode 100644
index 000000000000..13c1b03294a4
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_extended_hypercalls.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Test Hyper-V extended hypercall, HV_EXT_CALL_QUERY_CAPABILITIES (0x8001),
+ * exit to userspace and receive result in guest.
+ *
+ * Negative tests are present in hyperv_features.c
+ *
+ * Copyright 2022 Google LLC
+ * Author: Vipin Sharma <vipinsh@xxxxxxxxxx>
+ */
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "hyperv.h"
+
+/* Any value is fine */
+#define EXT_CAPABILITIES 0xbull
+
+static void guest_code(vm_vaddr_t in_pg_gpa, vm_vaddr_t out_pg_gpa,
+		       vm_vaddr_t out_pg_gva)
+{
+	uint64_t *output_gva;
+
+	wrmsr(HV_X64_MSR_GUEST_OS_ID, HYPERV_LINUX_OS_ID);
+	wrmsr(HV_X64_MSR_HYPERCALL, in_pg_gpa);
+
+	output_gva = (uint64_t *)out_pg_gva;
+
+	hyperv_hypercall(HV_EXT_CALL_QUERY_CAPABILITIES, in_pg_gpa, out_pg_gpa);
+
+	/* TLFS states output will be a uint64_t value */
+	GUEST_ASSERT_EQ(*output_gva, EXT_CAPABILITIES);
+
+	GUEST_DONE();
+}
+
+int main(void)
+{
+	vm_vaddr_t hcall_out_page;
+	vm_vaddr_t hcall_in_page;
+	struct kvm_vcpu *vcpu;
+	struct kvm_run *run;
+	struct kvm_vm *vm;
+	uint64_t *outval;
+	struct ucall uc;
+
+	/* Verify if extended hypercalls are supported */
+	if (!kvm_cpuid_has(kvm_get_supported_hv_cpuid(),
+			   X86_FEATURE_HYPERV_EXTENDED_HYPERCALLS)) {
+		print_skip("Extended calls not supported by the kernel");
+		exit(KSFT_SKIP);
+	}
+
+	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+	run = vcpu->run;
+	vcpu_enable_cap(vcpu, KVM_CAP_HYPERV_ENFORCE_CPUID, 1);
+	vcpu_set_hv_cpuid(vcpu);
+
+	/* Hypercall input */
+	hcall_in_page = vm_vaddr_alloc_pages(vm, 1);
+	memset(addr_gva2hva(vm, hcall_in_page), 0x0, vm->page_size);
+
+	/* Hypercall output */
+	hcall_out_page = vm_vaddr_alloc_pages(vm, 1);
+	memset(addr_gva2hva(vm, hcall_out_page), 0x0, vm->page_size);
+
+	vcpu_args_set(vcpu, 3, addr_gva2gpa(vm, hcall_in_page),
+		      addr_gva2gpa(vm, hcall_out_page), hcall_out_page);
+
+	vcpu_run(vcpu);
+
+	ASSERT_EXIT_REASON(vcpu, KVM_EXIT_HYPERV);
+
+	outval = addr_gpa2hva(vm, run->hyperv.u.hcall.params[1]);
+	*outval = EXT_CAPABILITIES;
+	run->hyperv.u.hcall.result = HV_STATUS_SUCCESS;
+
+	vcpu_run(vcpu);
+
+	ASSERT_EXIT_REASON(vcpu, KVM_EXIT_IO);
+
+	switch (get_ucall(vcpu, &uc)) {
+	case UCALL_ABORT:
+		REPORT_GUEST_ASSERT_2(uc, "arg1 = %ld, arg2 = %ld");
+		break;
+	case UCALL_DONE:
+		break;
+	default:
+		TEST_FAIL("Unhandled ucall: %ld", uc.cmd);
+	}
+
+	kvm_vm_free(vm);
+	return 0;
+}
-- 
2.38.1.584.g0f3c55d4c2-goog