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

1 files changed, 111 insertions, 0 deletions

diff --git a/usr.sbin/bhyve/bootrom.c b/usr.sbin/bhyve/bootrom.c
new file mode 100644
index 0000000..5e4e0e9
--- /dev/null
+++ b/usr.sbin/bhyve/bootrom.c
@@ -0,0 +1,111 @@
+/*-
+ * Copyright (c) 2015 Neel Natu <neel@freebsd.org>
+ * All rights reserved.
+ *
+ * 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 ``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>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+#include <machine/vmm.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdbool.h>
+
+#include <vmmapi.h>
+#include "bhyverun.h"
+#include "bootrom.h"
+
+#define	MAX_BOOTROM_SIZE	(16 * 1024 * 1024)	/* 16 MB */
+
+int
+bootrom_init(struct vmctx *ctx, const char *romfile)
+{
+	struct stat sbuf;
+	vm_paddr_t gpa;
+	ssize_t rlen;
+	char *ptr;
+	int fd, i, rv, prot;
+
+	rv = -1;
+	fd = open(romfile, O_RDONLY);
+	if (fd < 0) {
+		fprintf(stderr, "Error opening bootrom \"%s\": %s\n",
+		    romfile, strerror(errno));
+		goto done;
+	}
+
+        if (fstat(fd, &sbuf) < 0) {
+		fprintf(stderr, "Could not fstat bootrom file \"%s\": %s\n",
+		    romfile, strerror(errno));
+		goto done;
+        }
+
+	/*
+	 * Limit bootrom size to 16MB so it doesn't encroach into reserved
+	 * MMIO space (e.g. APIC, HPET, MSI).
+	 */
+	if (sbuf.st_size > MAX_BOOTROM_SIZE || sbuf.st_size < PAGE_SIZE) {
+		fprintf(stderr, "Invalid bootrom size %ld\n", sbuf.st_size);
+		goto done;
+	}
+
+	if (sbuf.st_size & PAGE_MASK) {
+		fprintf(stderr, "Bootrom size %ld is not a multiple of the "
+		    "page size\n", sbuf.st_size);
+		goto done;
+	}
+
+	ptr = vm_create_devmem(ctx, VM_BOOTROM, "bootrom", sbuf.st_size);
+	if (ptr == MAP_FAILED)
+		goto done;
+
+	/* Map the bootrom into the guest address space */
+	prot = PROT_READ | PROT_EXEC;
+	gpa = (1ULL << 32) - sbuf.st_size;
+	if (vm_mmap_memseg(ctx, gpa, VM_BOOTROM, 0, sbuf.st_size, prot) != 0)
+		goto done;
+
+	/* Read 'romfile' into the guest address space */
+	for (i = 0; i < sbuf.st_size / PAGE_SIZE; i++) {
+		rlen = read(fd, ptr + i * PAGE_SIZE, PAGE_SIZE);
+		if (rlen != PAGE_SIZE) {
+			fprintf(stderr, "Incomplete read of page %d of bootrom "
+			    "file %s: %ld bytes\n", i, romfile, rlen);
+			goto done;
+		}
+	}
+	rv = 0;
+done:
+	if (fd >= 0)
+		close(fd);
+	return (rv);
+}