src/cpu: add a basic RiscV64 cpu driver

There are tests in qemuxml2argvtest that will fail if we enable RISC-V
testing, with an error like the following:

"cpuGetSubDriver:64 : this function is not supported by the connection
driver: 'riscv64' architecture is not supp orted by CPU driver"

This happens because we don't have a RISC-V driver yet.

Add a barebone RISC-V driver to allow tests to be executed. The only 2
callbacks implemented here are 'compare' and 'validateFeatures', both
acting as a no-op. More callbacks and features will be added in the
future.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

src/cpu/cpu.c

@@ -27,6 +27,7 @@
 #include "cpu_ppc64.h"
 #include "cpu_s390.h"
 #include "cpu_arm.h"
+#include "cpu_riscv64.h"
 #include "capabilities.h"
 
 
@@ -39,6 +40,7 @@ static struct cpuArchDriver *drivers[] = {
     &cpuDriverPPC64,
     &cpuDriverS390,
     &cpuDriverArm,
+    &cpuDriverRiscv64,
 };
 
 

src/cpu/cpu_riscv64.c

@@ -0,0 +1,59 @@
+/*
+ * cpu_riscv64.c: CPU driver for riscv64 CPUs
+ *
+ * Copyright (C) 2023, Ventana Micro
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+
+#include "cpu.h"
+
+
+#define VIR_FROM_THIS VIR_FROM_CPU
+
+static const virArch archs[] = { VIR_ARCH_RISCV64 };
+
+static virCPUCompareResult
+virCPURiscv64Compare(virCPUDef *host G_GNUC_UNUSED,
+                     virCPUDef *cpu G_GNUC_UNUSED,
+                     bool failMessages G_GNUC_UNUSED)
+{
+    /*
+     * For now QEMU will perform all runtime checks.
+     */
+    return VIR_CPU_COMPARE_IDENTICAL;
+}
+
+
+static int
+virCPURiscv64ValidateFeatures(virCPUDef *cpu G_GNUC_UNUSED)
+{
+    return 0;
+}
+
+
+struct cpuArchDriver cpuDriverRiscv64 = {
+    .name = "riscv64",
+    .arch = archs,
+    .narch = G_N_ELEMENTS(archs),
+    .compare    = virCPURiscv64Compare,
+    .decode     = NULL,
+    .encode     = NULL,
+    .baseline   = NULL,
+    .update     = NULL,
+    .validateFeatures = virCPURiscv64ValidateFeatures,
+};

src/cpu/cpu_riscv64.h

@@ -0,0 +1,25 @@
+/*
+ * cpu_riscv64.h: CPU driver for riscv64 CPUs
+ *
+ * Copyright (c) 2023, Ventana Micro
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "cpu.h"
+
+extern struct cpuArchDriver cpuDriverRiscv64;

src/cpu/meson.build

@@ -3,6 +3,7 @@ cpu_sources = [
   'cpu_arm.c',
   'cpu_map.c',
   'cpu_ppc64.c',
+  'cpu_riscv64.c',
   'cpu_s390.c',
   'cpu_x86.c',
 ]