KVM: selftests: Test Hyper-V extended hypercall exit to userspace

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.

Add KVM_EXIT_HYPERV to list of "known" hypercalls so errors generate
pretty strings.

Signed-off-by: Vipin Sharma <vipinsh@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20221212183720.4062037-14-vipinsh@google.com
[sean: add KVM_EXIT_HYPERV to exit_reasons_known]
Signed-off-by: Sean Christopherson <seanjc@google.com>

3 files changed, 99 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 1750f91dd936..844417601618 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -67,6 +67,7 @@ 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/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 56d5ea949cbb..f25b3e9b5a07 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1844,6 +1844,7 @@ static struct exit_reason {
 	{KVM_EXIT_X86_RDMSR, "RDMSR"},
 	{KVM_EXIT_X86_WRMSR, "WRMSR"},
 	{KVM_EXIT_XEN, "XEN"},
+	{KVM_EXIT_HYPERV, "HYPERV"},
 #ifdef KVM_EXIT_MEMORY_NOT_PRESENT
 	{KVM_EXIT_MEMORY_NOT_PRESENT, "MEMORY_NOT_PRESENT"},
 #endif
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..73af44d2167f
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_extended_hypercalls.c
@@ -0,0 +1,97 @@
+// 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@google.com>
+ */
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "hyperv.h"
+
+/* Any value is fine */
+#define EXT_CAPABILITIES 0xbull
+
+static void guest_code(vm_paddr_t in_pg_gpa, vm_paddr_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(),
+			   HV_ENABLE_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_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);
+
+	TEST_ASSERT(run->exit_reason == KVM_EXIT_HYPERV,
+		    "Unexpected exit reason: %u (%s)",
+		    run->exit_reason, exit_reason_str(run->exit_reason));
+
+	outval = addr_gpa2hva(vm, run->hyperv.u.hcall.params[1]);
+	*outval = EXT_CAPABILITIES;
+	run->hyperv.u.hcall.result = HV_STATUS_SUCCESS;
+
+	vcpu_run(vcpu);
+
+	TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+		    "Unexpected exit reason: %u (%s)",
+		    run->exit_reason, exit_reason_str(run->exit_reason));
+
+	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;
+}