From 67c92f3fec63f064a479c873fb14303a60d96f87 Mon Sep 17 00:00:00 2001
From: Daan De Meyer <daan.j.demeyer@gmail.com>
Date: Thu, 28 Sep 2023 09:50:36 +0200
Subject: [PATCH] kmod-setup: Load virtiofs and virtio_pci early

There's no way for us to wait for specific virtiofs tags to appear,
so we have to try and make sure that the tags are all available by
the time we try to mount any virtiofs tag. Let's try to do that by
loading the necessary modules as early as we can.
---
 src/core/kmod-setup.c | 63 +++++++++++++++++--------------------------
 1 file changed, 25 insertions(+), 38 deletions(-)

diff --git a/src/core/kmod-setup.c b/src/core/kmod-setup.c
index a99309f5c2..b8e3f7aadd 100644
--- a/src/core/kmod-setup.c
+++ b/src/core/kmod-setup.c
@@ -65,7 +65,7 @@ static int match_modalias_recurse_dir_cb(
         return RECURSE_DIR_LEAVE_DIRECTORY;
 }
 
-static bool has_virtio_rng(void) {
+static bool has_virtio_feature(const char *name, char **modaliases) {
         int r;
 
         /* Directory traversal might be slow, hence let's do a cheap check first if it's even worth it */
@@ -76,56 +76,34 @@ static bool has_virtio_rng(void) {
                         AT_FDCWD,
                         "/sys/devices/pci0000:00",
                         /* statx_mask= */ 0,
-                        /* n_depth_max= */ 2,
+                        /* n_depth_max= */ 3,
                         RECURSE_DIR_ENSURE_TYPE,
                         match_modalias_recurse_dir_cb,
-                        STRV_MAKE("pci:v00001AF4d00001005", "pci:v00001AF4d00001044"));
+                        modaliases);
         if (r < 0)
-                log_debug_errno(r, "Failed to determine whether host has virtio-rng device, ignoring: %m");
+                log_debug_errno(r, "Failed to determine whether host has %s device, ignoring: %m", name);
 
         return r > 0;
 }
 
+static bool has_virtio_rng(void) {
+        return has_virtio_feature("virtio-rng", STRV_MAKE("pci:v00001AF4d00001005", "pci:v00001AF4d00001044"));
+}
+
 static bool has_virtio_console(void) {
-        int r;
-
-        /* Directory traversal might be slow, hence let's do a cheap check first if it's even worth it */
-        if (detect_vm() == VIRTUALIZATION_NONE)
-                return false;
-
-        r = recurse_dir_at(
-                        AT_FDCWD,
-                        "/sys/devices/pci0000:00",
-                        /* statx_mask= */ 0,
-                        /* n_depth_max= */ 3,
-                        RECURSE_DIR_ENSURE_TYPE,
-                        match_modalias_recurse_dir_cb,
-                        STRV_MAKE("virtio:d00000003v", "virtio:d0000000Bv"));
-        if (r < 0)
-                log_debug_errno(r, "Failed to determine whether host has virtio-console device, ignoring: %m");
-
-        return r > 0;
+        return has_virtio_feature("virtio-console", STRV_MAKE("virtio:d00000003v", "virtio:d0000000Bv"));
 }
 
 static bool has_virtio_vsock(void) {
-        int r;
+        return has_virtio_feature("virtio-vsock", STRV_MAKE("virtio:d00000013v"));
+}
 
-        /* Directory traversal might be slow, hence let's do a cheap check first if it's even worth it */
-        if (detect_vm() == VIRTUALIZATION_NONE)
-                return false;
+static bool has_virtiofs(void) {
+        return has_virtio_feature("virtiofs", STRV_MAKE("virtio:d0000001Av"));
+}
 
-        r = recurse_dir_at(
-                        AT_FDCWD,
-                        "/sys/devices/pci0000:00",
-                        /* statx_mask= */ 0,
-                        /* n_depth_max= */ 3,
-                        RECURSE_DIR_ENSURE_TYPE,
-                        match_modalias_recurse_dir_cb,
-                        STRV_MAKE("virtio:d00000013v"));
-        if (r < 0)
-                log_debug_errno(r, "Failed to determine whether host has virtio-vsock device, ignoring: %m");
-
-        return r > 0;
+static bool has_virtio_pci(void) {
+        return has_virtio_feature("virtio-pci", STRV_MAKE("pci:v00001AF4d"));
 }
 
 static bool in_qemu(void) {
@@ -168,6 +146,15 @@ int kmod_setup(void) {
                 /* Make sure we can send sd-notify messages over vsock as early as possible. */
                 { "vmw_vsock_virtio_transport", NULL,                        false, false, has_virtio_vsock   },
 
+                /* We can't wait for specific virtiofs tags to show up as device nodes so we have to load the
+                 * virtiofs and virtio_pci modules early to make sure the virtiofs tags are found when
+                 * sysroot.mount is started.
+                 *
+                 * TODO: Remove these again once https://gitlab.com/virtio-fs/virtiofsd/-/issues/128 is
+                 * resolved and the kernel fix is widely available. */
+                { "virtiofs",                   "/sys/module/virtiofs",      false, false, has_virtiofs       },
+                { "virtio_pci",                 "/sys/module/virtio_pci",    false, false, has_virtio_pci     },
+
                 /* qemu_fw_cfg would be loaded by udev later, but we want to import credentials from it super early */
                 { "qemu_fw_cfg",                "/sys/firmware/qemu_fw_cfg", false, false, in_qemu            },