git: 0e1f5ab7db2c - main - virtio_mmio: Support command-line parameters

From: Colin Percival <cperciva_at_FreeBSD.org>
Date: Tue, 18 Oct 2022 06:03:05 UTC
The branch main has been updated by cperciva:

URL: https://cgit.FreeBSD.org/src/commit/?id=0e1f5ab7db2cd2837f97f169122897b19c185dbd

commit 0e1f5ab7db2cd2837f97f169122897b19c185dbd
Author:     Colin Percival <cperciva@FreeBSD.org>
AuthorDate: 2022-08-13 00:54:26 +0000
Commit:     Colin Percival <cperciva@FreeBSD.org>
CommitDate: 2022-10-18 06:02:21 +0000

    virtio_mmio: Support command-line parameters
    
    The Virtio MMIO bus driver was added in 2014 with support for devices
    exposed via FDT; in 2018 support was added to discover Virtio MMIO
    devices via ACPI tables, as in QEMU.  The Firecracker VMM eschews both
    FDT and ACPI, instead presenting device information via kernel command
    line arguments of the form virtio_mmio.device=<parameters>.
    
    These command line parameters get converted into kernel environment
    variables; this adds support for parsing those variables and attaching
    virtio_mmio children to nexus.
    
    There is a case to be made that it would be cleaner to have a new
    "cmdlinebus" attached to nexus and virtio_mmio children attached to
    that.  A future commit might do that.
    
    Discussed with: imp, jrtc27
    Sponsored by:   https://patreon.com/cperciva
    Differential Revision:  https://reviews.freebsd.org/D36189
---
 sys/conf/files                            |   1 +
 sys/dev/virtio/mmio/virtio_mmio_cmdline.c | 150 ++++++++++++++++++++++++++++++
 2 files changed, 151 insertions(+)

diff --git a/sys/conf/files b/sys/conf/files
index b7da3626111d..39e6d4aaf0a8 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -3437,6 +3437,7 @@ dev/virtio/pci/virtio_pci_legacy.c	optional	virtio_pci
 dev/virtio/pci/virtio_pci_modern.c	optional	virtio_pci
 dev/virtio/mmio/virtio_mmio.c		optional	virtio_mmio
 dev/virtio/mmio/virtio_mmio_acpi.c	optional	virtio_mmio acpi
+dev/virtio/mmio/virtio_mmio_cmdline.c	optional	virtio_mmio
 dev/virtio/mmio/virtio_mmio_fdt.c	optional	virtio_mmio fdt
 dev/virtio/mmio/virtio_mmio_if.m	optional	virtio_mmio
 dev/virtio/network/if_vtnet.c		optional	vtnet
diff --git a/sys/dev/virtio/mmio/virtio_mmio_cmdline.c b/sys/dev/virtio/mmio/virtio_mmio_cmdline.c
new file mode 100644
index 000000000000..cb4762adc964
--- /dev/null
+++ b/sys/dev/virtio/mmio/virtio_mmio_cmdline.c
@@ -0,0 +1,150 @@
+/*-
+ * Copyright (c) 2022 Colin Percival
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/bus.h>
+#include <sys/kernel.h>
+#include <sys/limits.h>
+#include <sys/malloc.h>
+#include <sys/module.h>
+#include <sys/rman.h>
+
+#include <machine/bus.h>
+#include <machine/resource.h>
+
+#include <dev/virtio/mmio/virtio_mmio.h>
+
+/* Parse <size>@<baseaddr>:<irq>[:<id>] and add a child. */
+static void
+parsearg(driver_t *driver, device_t parent, char * arg)
+{
+	device_t child;
+	char * p;
+	unsigned long sz;
+	unsigned long baseaddr;
+	unsigned long irq;
+	unsigned long id;
+
+	/* <size> */
+	sz = strtoul(arg, &p, 0);
+	if ((sz == 0) || (sz == ULONG_MAX))
+		goto bad;
+	switch (*p) {
+	case 'E': case 'e':
+		sz <<= 10;
+		/* FALLTHROUGH */
+	case 'P': case 'p':
+		sz <<= 10;
+		/* FALLTHROUGH */
+	case 'T': case 't':
+		sz <<= 10;
+		/* FALLTHROUGH */
+	case 'G': case 'g':
+		sz <<= 10;
+		/* FALLTHROUGH */
+	case 'M': case 'm':
+		sz <<= 10;
+		/* FALLTHROUGH */
+	case 'K': case 'k':
+		sz <<= 10;
+		p++;
+		break;
+	}
+
+	/* @<baseaddr> */
+	if (*p++ != '@')
+		goto bad;
+	baseaddr = strtoul(p, &p, 0);
+	if ((baseaddr == 0) || (baseaddr == ULONG_MAX))
+		goto bad;
+
+	/* :<irq> */
+	if (*p++ != ':')
+		goto bad;
+	irq = strtoul(p, &p, 0);
+	if ((irq == 0) || (irq == ULONG_MAX))
+		goto bad;
+
+	/* Optionally, :<id> */
+	if (*p) {
+		if (*p++ != ':')
+			goto bad;
+		id = strtoul(p, &p, 0);
+		if ((id == 0) || (id == ULONG_MAX))
+			goto bad;
+	} else {
+		id = 0;
+	}
+
+	/* Should have reached the end of the string. */
+	if (*p)
+		goto bad;
+
+	/* Create the child and assign its resources. */
+	child = BUS_ADD_CHILD(parent, 0, driver->name, id ? id : -1);
+	bus_set_resource(child, SYS_RES_MEMORY, 0, baseaddr, sz);
+	bus_set_resource(child, SYS_RES_IRQ, 0, irq, 1);
+	device_set_driver(child, driver);
+
+	return;
+
+bad:
+	printf("Error parsing virtio_mmio parameter: %s\n", arg);
+}
+
+static void
+vtmmio_cmdline_identify(driver_t *driver, device_t parent)
+{
+	size_t n;
+	char name[] = "virtio_mmio.device_XXXX";
+	char * val;
+
+	/* First variable just has its own name. */
+	if ((val = kern_getenv("virtio_mmio.device")) == NULL)
+		return;
+	parsearg(driver, parent, val);
+	freeenv(val);
+
+	/* The rest have _%zu suffixes. */
+	for (n = 1; n <= 9999; n++) {
+		sprintf(name, "virtio_mmio.device_%zu", n);
+		if ((val = kern_getenv(name)) == NULL)
+			return;
+		parsearg(driver, parent, val);
+		freeenv(val);
+	}
+}
+
+static device_method_t vtmmio_cmdline_methods[] = {
+        /* Device interface. */
+	DEVMETHOD(device_identify,	vtmmio_cmdline_identify),
+	DEVMETHOD(device_probe,		vtmmio_probe),
+
+        DEVMETHOD_END
+};
+DEFINE_CLASS_1(virtio_mmio, vtmmio_cmdline_driver, vtmmio_cmdline_methods,
+    sizeof(struct vtmmio_softc), vtmmio_driver);
+DRIVER_MODULE(vtmmio_cmdline, nexus, vtmmio_cmdline_driver, 0, 0);