Restructure memory allocation in bhyve to support "devmem".

devmem is used to represent MMIO devices like the boot ROM or a VESA framebuffer
where doing a trap-and-emulate for every access is impractical. devmem is a
hybrid of system memory (sysmem) and emulated device models.

devmem is mapped in the guest address space via nested page tables similar
to sysmem. However the address range where devmem is mapped may be changed
by the guest at runtime (e.g. by reprogramming a PCI BAR). Also devmem is
usually mapped RO or RW as compared to RWX mappings for sysmem.

Each devmem segment is named (e.g. "bootrom") and this name is used to
create a device node for the devmem segment (e.g. /dev/vmm/testvm.bootrom).
The device node supports mmap(2) and this decouples the host mapping of
devmem from its mapping in the guest address space (which can change).

Reviewed by:	tychon
Discussed with:	grehan
Differential Revision:	https://reviews.freebsd.org/D2762
MFC after:	4 weeks

2 files changed, 12 insertions, 4 deletions

diff --git a/usr.sbin/bhyveload/bhyveload.8 b/usr.sbin/bhyveload/bhyveload.8
index c168832..fc9c8e1 100644
--- a/usr.sbin/bhyveload/bhyveload.8
+++ b/usr.sbin/bhyveload/bhyveload.8
@@ -35,6 +35,7 @@
 guest inside a bhyve virtual machine
 .Sh SYNOPSIS
 .Nm
+.Op Fl S
 .Op Fl c Ar cons-dev
 .Op Fl d Ar disk-path
 .Op Fl e Ar name=value
@@ -111,8 +112,10 @@ respectively.
 The default value of
 .Ar mem-size
 is 256M.
-.El
+.It Fl S
+Wire guest memory.
 .Sh EXAMPLES
+.El
 To create a virtual machine named
 .Ar freebsd-vm
 that boots off the ISO image
diff --git a/usr.sbin/bhyveload/bhyveload.c b/usr.sbin/bhyveload/bhyveload.c
index 8ebf116..8178bb2 100644
--- a/usr.sbin/bhyveload/bhyveload.c
+++ b/usr.sbin/bhyveload/bhyveload.c
@@ -629,7 +629,7 @@ usage(void)
 {
 
 	fprintf(stderr,
-	    "usage: %s [-c <console-device>] [-d <disk-path>] [-e <name=value>]\n"
+	    "usage: %s [-S][-c <console-device>] [-d <disk-path>] [-e <name=value>]\n"
 	    "       %*s [-h <host-path>] [-m mem-size] <vmname>\n",
 	    progname,
 	    (int)strlen(progname), "");
@@ -642,16 +642,17 @@ main(int argc, char** argv)
 	void *h;
 	void (*func)(struct loader_callbacks *, void *, int, int);
 	uint64_t mem_size;
-	int opt, error, need_reinit;
+	int opt, error, need_reinit, memflags;
 
 	progname = basename(argv[0]);
 
+	memflags = 0;
 	mem_size = 256 * MB;
 
 	consin_fd = STDIN_FILENO;
 	consout_fd = STDOUT_FILENO;
 
-	while ((opt = getopt(argc, argv, "c:d:e:h:m:")) != -1) {
+	while ((opt = getopt(argc, argv, "Sc:d:e:h:m:")) != -1) {
 		switch (opt) {
 		case 'c':
 			error = altcons_open(optarg);
@@ -678,6 +679,9 @@ main(int argc, char** argv)
 			if (error != 0)
 				errx(EX_USAGE, "Invalid memsize '%s'", optarg);
 			break;
+		case 'S':
+			memflags |= VM_MEM_F_WIRED;
+			break;
 		case '?':
 			usage();
 		}
@@ -715,6 +719,7 @@ main(int argc, char** argv)
 		}
 	}
 
+	vm_set_memflags(ctx, memflags);
 	error = vm_setup_memory(ctx, mem_size, VM_MMAP_ALL);
 	if (error) {
 		perror("vm_setup_memory");