14660 expose bhyve kernel interface version

Reviewed by: Andy Fiddaman <andy@omnios.org>
Reviewed by: Toomas Soome <tsoome@me.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

6 files changed, 74 insertions, 1 deletions

diff --git a/usr/src/pkg/manifests/system-bhyve-tests.p5m b/usr/src/pkg/manifests/system-bhyve-tests.p5m
index 1a0ba140ce..d4c8be469f 100644
--- a/usr/src/pkg/manifests/system-bhyve-tests.p5m
+++ b/usr/src/pkg/manifests/system-bhyve-tests.p5m
@@ -50,6 +50,7 @@ file path=opt/bhyve-tests/tests/mevent/vnode_file mode=0555
 file path=opt/bhyve-tests/tests/mevent/vnode_zvol mode=0555
 dir  path=opt/bhyve-tests/tests/vmm
 file path=opt/bhyve-tests/tests/vmm/fpu_getset mode=0555
+file path=opt/bhyve-tests/tests/vmm/interface_version mode=0555
 file path=opt/bhyve-tests/tests/vmm/mem_devmem mode=0555
 file path=opt/bhyve-tests/tests/vmm/mem_partial mode=0555
 file path=opt/bhyve-tests/tests/vmm/mem_seg_map mode=0555
diff --git a/usr/src/test/bhyve-tests/runfiles/default.run b/usr/src/test/bhyve-tests/runfiles/default.run
index 476fa5f839..9296a30852 100644
--- a/usr/src/test/bhyve-tests/runfiles/default.run
+++ b/usr/src/test/bhyve-tests/runfiles/default.run
@@ -23,6 +23,7 @@ outputdir = /var/tmp/test_results
 user = root
 tests = [
 	'fpu_getset',
+	'interface_version',
 	'mem_devmem',
 	'mem_partial',
 	'mem_seg_map'
diff --git a/usr/src/test/bhyve-tests/tests/vmm/Makefile b/usr/src/test/bhyve-tests/tests/vmm/Makefile
index 1620706cb6..eeca882915 100644
--- a/usr/src/test/bhyve-tests/tests/vmm/Makefile
+++ b/usr/src/test/bhyve-tests/tests/vmm/Makefile
@@ -18,7 +18,8 @@ include $(SRC)/test/Makefile.com
 PROG =	mem_partial \
 	mem_seg_map \
 	mem_devmem \
-	fpu_getset
+	fpu_getset \
+	interface_version
 
 COMMON_OBJS =	common.o
 CLEAN_OBJS =	$(PROG:%=%.o)
diff --git a/usr/src/test/bhyve-tests/tests/vmm/interface_version.c b/usr/src/test/bhyve-tests/tests/vmm/interface_version.c
new file mode 100644
index 0000000000..b3de2f4f4f
--- /dev/null
+++ b/usr/src/test/bhyve-tests/tests/vmm/interface_version.c
@@ -0,0 +1,48 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright 2022 Oxide Computer Company
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <libgen.h>
+
+#include <sys/vmm.h>
+#include <sys/vmm_dev.h>
+
+int
+main(int argc, char *argv[])
+{
+	const char *suite_name = basename(argv[0]);
+
+	int ctl_fd = open(VMM_CTL_DEV, O_EXCL | O_RDWR);
+	if (ctl_fd < 0) {
+		perror("could not open vmmctl device");
+	}
+
+	int version = ioctl(ctl_fd, VMM_INTERFACE_VERSION, 0);
+	if (version < 0) {
+		perror("VMM_INTERFACE_VERSION ioctl failed");
+	}
+	if (version != VMM_CURRENT_INTERFACE_VERSION) {
+		(void) fprintf(stderr, "kernel version %d != expected %d\n",
+		    version, VMM_CURRENT_INTERFACE_VERSION);
+		return (EXIT_FAILURE);
+	}
+
+	(void) close(ctl_fd);
+	(void) printf("%s\tPASS\n", suite_name);
+	return (0);
+}
diff --git a/usr/src/uts/intel/io/vmm/vmm_sol_dev.c b/usr/src/uts/intel/io/vmm/vmm_sol_dev.c
index 3474ba905b..60a888e600 100644
--- a/usr/src/uts/intel/io/vmm/vmm_sol_dev.c
+++ b/usr/src/uts/intel/io/vmm/vmm_sol_dev.c
@@ -2489,6 +2489,9 @@ vmm_ctl_ioctl(int cmd, intptr_t arg, int md, cred_t *cr, int *rvalp)
 	}
 	case VMM_VM_SUPPORTED:
 		return (vmm_is_supported(arg));
+	case VMM_INTERFACE_VERSION:
+		*rvalp = VMM_CURRENT_INTERFACE_VERSION;
+		return (0);
 	case VMM_RESV_QUERY:
 	case VMM_RESV_ADD:
 	case VMM_RESV_REMOVE:
diff --git a/usr/src/uts/intel/sys/vmm_dev.h b/usr/src/uts/intel/sys/vmm_dev.h
index 027a7da214..0e883f21bb 100644
--- a/usr/src/uts/intel/sys/vmm_dev.h
+++ b/usr/src/uts/intel/sys/vmm_dev.h
@@ -350,6 +350,24 @@ struct vmm_dirty_tracker {
 	void		*vdt_pfns;	/* bit vector of dirty bits */
 };
 
+/*
+ * VMM Interface Version
+ *
+ * Despite the fact that the kernel interface to bhyve is explicitly considered
+ * Private, there are out-of-gate consumers which utilize it.  While they assume
+ * the risk of any breakage incurred by changes to bhyve, we can at least try to
+ * make it easier to detect changes by exposing a "version" of the interface.
+ * It can also be used by the in-gate userland to detect if packaging updates
+ * somehow result in the userland and kernel falling out of sync.
+ *
+ * There are no established criteria for the magnitude of change which requires
+ * this version to be incremented, and maintenance of it is considered a
+ * best-effort activity.  Nothing is to be inferred about the magnitude of a
+ * change when the version is modified.  It follows no rules like semver.
+ */
+#define	VMM_CURRENT_INTERFACE_VERSION	1
+
+
 #define	VMMCTL_IOC_BASE		(('V' << 16) | ('M' << 8))
 #define	VMM_IOC_BASE		(('v' << 16) | ('m' << 8))
 #define	VMM_LOCK_IOC_BASE	(('v' << 16) | ('l' << 8))
@@ -359,6 +377,7 @@ struct vmm_dirty_tracker {
 #define	VMM_CREATE_VM		(VMMCTL_IOC_BASE | 0x01)
 #define	VMM_DESTROY_VM		(VMMCTL_IOC_BASE | 0x02)
 #define	VMM_VM_SUPPORTED	(VMMCTL_IOC_BASE | 0x03)
+#define	VMM_INTERFACE_VERSION	(VMMCTL_IOC_BASE | 0x04)
 
 #define	VMM_RESV_QUERY		(VMMCTL_IOC_BASE | 0x10)
 #define	VMM_RESV_ADD		(VMMCTL_IOC_BASE | 0x11)