KVM: selftests: Add helpers to do KVM_HC_MAP_GPA_RANGE hypercalls (x86)

Add helpers for x86 guests to invoke the KVM_HC_MAP_GPA_RANGE hypercall,
which KVM will forward to userspace and thus can be used by tests to
coordinate private<=>shared conversions between host userspace code and
guest code.

Signed-off-by: Vishal Annapurve <vannapurve@google.com>
[sean: drop shared/private helpers (let tests specify flags)]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20231027182217.3615211-29-seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Author: vishals4gh

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

@@ -15,6 +15,7 @@
 #include <asm/msr-index.h>
 #include <asm/prctl.h>
 
+#include <linux/kvm_para.h>
 #include <linux/stringify.h>
 
 #include "../kvm_util.h"
@@ -1194,6 +1195,20 @@ uint64_t kvm_hypercall(uint64_t nr, uint64_t a0, uint64_t a1, uint64_t a2,
 uint64_t __xen_hypercall(uint64_t nr, uint64_t a0, void *a1);
 void xen_hypercall(uint64_t nr, uint64_t a0, void *a1);
 
+static inline uint64_t __kvm_hypercall_map_gpa_range(uint64_t gpa,
+						     uint64_t size, uint64_t flags)
+{
+	return kvm_hypercall(KVM_HC_MAP_GPA_RANGE, gpa, size >> PAGE_SHIFT, flags, 0);
+}
+
+static inline void kvm_hypercall_map_gpa_range(uint64_t gpa, uint64_t size,
+					       uint64_t flags)
+{
+	uint64_t ret = __kvm_hypercall_map_gpa_range(gpa, size, flags);
+
+	GUEST_ASSERT(!ret);
+}
+
 void __vm_xsave_require_permission(uint64_t xfeature, const char *name);
 
 #define vm_xsave_require_permission(xfeature)	\