From: Daan De Meyer <daan.j.demeyer@gmail.com>
Date: Tue, 12 Apr 2022 11:58:58 +0000 (+0200)
Subject: Add --qemu-kvm option
X-Git-Tag: v13~50^2~10
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f1d87c852ed8dc6d748edec456ff039d8e39f34d;p=thirdparty%2Fmkosi.git

Add --qemu-kvm option

Allows running without KVM acceleration on machines that support KVM.
Useful when trying to reproduce CI issues where KVM is not supported.
---

diff --git a/NEWS.md b/NEWS.md
index 8054657f7..247b99d78 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -15,6 +15,7 @@
   mkosi won't automatically build new unified kernel images anymore when a kernel is updated or installed. To keep this
   behavior, you can install the kernel-install script manually via a skeleton tree. The original script can be found
   [here](https://github.com/systemd/mkosi/blob/3798eb0c2ebcdf7dac207a559a3cb5a65cdb77b0/mkosi/resources/dracut_unified_kernel_install.sh).
+- Added QemuKvm option to configure whether to use KVM or not when running `mkosi qemu`.
 
 ## v12
 
diff --git a/mkosi.md b/mkosi.md
index 0ad3f43be..9e54317d8 100644
--- a/mkosi.md
+++ b/mkosi.md
@@ -1095,6 +1095,12 @@ a machine ID.
 : When used with the `qemu` verb, this options sets `qemu`'s `-m`
   argument which controls the amount of guest's RAM. Defaults to `1G`.
 
+`QemuKvm=`, `--qemu-kvm=`
+
+: When used with the `qemu` verb, this option specifies whether QEMU
+  should use KVM acceleration. Defaults to yes if the host machine
+  supports KVM acceleration, no otherwise.
+
 `NspawnKeepUnit=`, `--nspawn-keep-unit`
 
 : When used, this option instructs underlying calls of systemd-nspawn to
diff --git a/mkosi/__init__.py b/mkosi/__init__.py
index 96cded114..3e343e471 100644
--- a/mkosi/__init__.py
+++ b/mkosi/__init__.py
@@ -5624,6 +5624,8 @@ def create_parser() -> ArgumentParserMkosi:
     group.add_argument("--qemu-headless", action=BooleanAction, help="Configure image for qemu's -nographic mode")
     group.add_argument("--qemu-smp", help="Configure guest's SMP settings", metavar="SMP", default="2")
     group.add_argument("--qemu-mem", help="Configure guest's RAM size", metavar="MEM", default="1G")
+    group.add_argument("--qemu-kvm", action=BooleanAction, help="Configure whether to use KVM or not",
+                       default=qemu_check_kvm_support())
     group.add_argument(
         "--nspawn-keep-unit",
         action=BooleanAction,
@@ -6638,6 +6640,9 @@ def load_args(args: argparse.Namespace) -> MkosiArgs:
     if args.base_image is not None:
         args.base_packages = False
 
+    if args.qemu_kvm and not qemu_check_kvm_support():
+        die("Sorry, the host machine does not support KVM acceleration.")
+
     return MkosiArgs(**vars(args))
 
 
@@ -7636,8 +7641,7 @@ def qemu_check_kvm_support() -> bool:
 
 @contextlib.contextmanager
 def run_qemu_cmdline(args: MkosiArgs) -> Iterator[List[str]]:
-    has_kvm = qemu_check_kvm_support()
-    accel = "kvm" if has_kvm else "tcg"
+    accel = "kvm" if args.qemu_kvm else "tcg"
 
     firmware, fw_supports_sb = find_qemu_firmware()
 
@@ -7655,7 +7659,7 @@ def run_qemu_cmdline(args: MkosiArgs) -> Iterator[List[str]]:
         "virtio-rng-pci,rng=rng0,id=rng-device0",
     ]
 
-    if has_kvm:
+    if args.qemu_kvm:
         cmdline += ["-cpu", "host"]
 
     if args.qemu_headless:
diff --git a/mkosi/backend.py b/mkosi/backend.py
index 36c856f99..d424a2717 100644
--- a/mkosi/backend.py
+++ b/mkosi/backend.py
@@ -516,6 +516,7 @@ class MkosiArgs:
     qemu_headless: bool
     qemu_smp: str
     qemu_mem: str
+    qemu_kvm: bool
 
     # systemd-nspawn specific options
     nspawn_keep_unit: bool
diff --git a/tests/test_config_parser.py b/tests/test_config_parser.py
index 7f8e1bd56..ee1b01a0d 100644
--- a/tests/test_config_parser.py
+++ b/tests/test_config_parser.py
@@ -132,6 +132,7 @@ class MkosiConfig:
             "qemu_headless": False,
             "qemu_smp": "2",
             "qemu_mem": "1G",
+            "qemu_kvm": mkosi.qemu_check_kvm_support(),
             "nspawn_keep_unit": False,
             "netdev": False,
             "ephemeral": False,