vmd(8): scan pci bus to determine bootorder strings.

vmd's SeaBIOS bootorder strings had hardcoded pci device ids, so
if a user added a network interface the bootorder strings didn't
line up with reality. Using vmctl(8) to boot from a cdrom (-B cdrom)
would fail, for instance, if attaching both a nic and a disk as
well.

This change scans the pci devices and finds the first of each type
to construct viable bootorder strings.

ok jan@

4 files changed, 49 insertions, 16 deletions

diff --git a/usr.sbin/vmd/fw_cfg.c b/usr.sbin/vmd/fw_cfg.c
index ed4386b7c9c..b875082b6fe 100644
--- a/usr.sbin/vmd/fw_cfg.c
+++ b/usr.sbin/vmd/fw_cfg.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: fw_cfg.c,v 1.6 2022/12/26 23:50:20 dv Exp $	*/
+/*	$OpenBSD: fw_cfg.c,v 1.7 2023/02/06 20:33:34 dv Exp $	*/
 /*
  * Copyright (c) 2018 Claudio Jeker <claudio@openbsd.org>
  *
@@ -18,12 +18,14 @@
 #include <sys/uio.h>
 #include <machine/biosvar.h>	/* bios_memmap_t */
 #include <machine/vmmvar.h>
+#include <dev/pv/virtioreg.h>
 
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
 #include "atomicio.h"
+#include "pci.h"
 #include "vmd.h"
 #include "vmm.h"
 #include "fw_cfg.h"
@@ -72,9 +74,11 @@ static void	fw_cfg_file_dir(void);
 void
 fw_cfg_init(struct vmop_create_params *vmc)
 {
-	const char *bootorder = NULL;
 	unsigned int sd = 0;
 	size_t i, e820_len = 0;
+	char bootorder[64];
+	const char *bootfmt;
+	int bootidx = -1;
 
 	/* Define e820 memory ranges. */
 	memset(&e820, 0, sizeof(e820));
@@ -96,18 +100,24 @@ fw_cfg_init(struct vmop_create_params *vmc)
 
 	switch (vmc->vmc_bootdevice) {
 	case VMBOOTDEV_DISK:
-		bootorder = "/pci@i0cf8/*@3\nHALT";
+		bootidx = pci_find_first_device(PCI_PRODUCT_VIRTIO_BLOCK);
+		bootfmt = "/pci@i0cf8/*@%d\nHALT";
 		break;
 	case VMBOOTDEV_CDROM:
-		bootorder = "/pci@i0cf8/*@4/*@0/*@0,40000100\nHALT";
+		bootidx = pci_find_first_device(PCI_PRODUCT_VIRTIO_SCSI);
+		bootfmt = "/pci@i0cf8/*@%d/*@0/*@0,40000100\nHALT";
 		break;
 	case VMBOOTDEV_NET:
 		/* XXX not yet */
-		bootorder = "HALT";
+		bootidx = pci_find_first_device(PCI_PRODUCT_VIRTIO_NETWORK);
+		bootfmt = "HALT";
 		break;
 	}
-	if (bootorder)
+	if (bootidx > -1) {
+		snprintf(bootorder, sizeof(bootorder), bootfmt, bootidx);
+		log_debug("%s: bootorder: %s", __func__, bootorder);
 		fw_cfg_add_file("bootorder", bootorder, strlen(bootorder) + 1);
+	}
 }
 
 int
diff --git a/usr.sbin/vmd/pci.c b/usr.sbin/vmd/pci.c
index c1cd8154663..5309449b339 100644
--- a/usr.sbin/vmd/pci.c
+++ b/usr.sbin/vmd/pci.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pci.c,v 1.30 2023/01/28 14:40:53 dv Exp $	*/
+/*	$OpenBSD: pci.c,v 1.31 2023/02/06 20:33:34 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
@@ -437,3 +437,21 @@ pci_restore(int fd)
 	}
 	return (0);
 }
+
+/*
+ * Find the first PCI device based on PCI Subsystem ID
+ * (e.g. PCI_PRODUCT_VIRTIO_BLOCK).
+ *
+ * Returns the PCI device id of the first matching device, if found.
+ * Otherwise, returns -1.
+ */
+int
+pci_find_first_device(uint16_t subsys_id)
+{
+	int i;
+
+	for (i = 0; i < pci.pci_dev_ct; i++)
+		if (pci.pci_devices[i].pd_subsys_id == subsys_id)
+			return (i);
+	return (-1);
+}
diff --git a/usr.sbin/vmd/pci.h b/usr.sbin/vmd/pci.h
index ed6ba534536..73b54437bed 100644
--- a/usr.sbin/vmd/pci.h
+++ b/usr.sbin/vmd/pci.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pci.h,v 1.9 2021/06/16 16:55:02 dv Exp $	*/
+/*	$OpenBSD: pci.h,v 1.10 2023/02/06 20:33:34 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
@@ -92,6 +92,7 @@ struct pci {
 	struct pci_dev pci_devices[PCI_CONFIG_MAX_DEV];
 };
 
+int pci_find_first_device(uint16_t);
 void pci_handle_address_reg(struct vm_run_params *);
 void pci_handle_data_reg(struct vm_run_params *);
 uint8_t pci_handle_io(struct vm_run_params *);
diff --git a/usr.sbin/vmd/vm.c b/usr.sbin/vmd/vm.c
index bf8b0b958f5..5b9a1831f5b 100644
--- a/usr.sbin/vmd/vm.c
+++ b/usr.sbin/vmd/vm.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vm.c,v 1.82 2023/01/28 14:40:53 dv Exp $	*/
+/*	$OpenBSD: vm.c,v 1.83 2023/02/06 20:33:34 dv Exp $	*/
 
 /*
  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
@@ -1106,13 +1106,6 @@ init_emulated_hw(struct vmop_create_params *vmc, int child_cdrom,
 	for (i = COM1_DATA; i <= COM1_SCR; i++)
 		ioports_map[i] = vcpu_exit_com;
 
-	/* Init QEMU fw_cfg interface */
-	fw_cfg_init(vmc);
-	ioports_map[FW_CFG_IO_SELECT] = vcpu_exit_fw_cfg;
-	ioports_map[FW_CFG_IO_DATA] = vcpu_exit_fw_cfg;
-	ioports_map[FW_CFG_IO_DMA_ADDR_HIGH] = vcpu_exit_fw_cfg_dma;
-	ioports_map[FW_CFG_IO_DMA_ADDR_LOW] = vcpu_exit_fw_cfg_dma;
-
 	/* Initialize PCI */
 	for (i = VM_PCI_IO_BAR_BASE; i <= VM_PCI_IO_BAR_END; i++)
 		ioports_map[i] = vcpu_exit_pci;
@@ -1126,7 +1119,18 @@ init_emulated_hw(struct vmop_create_params *vmc, int child_cdrom,
 
 	/* Initialize virtio devices */
 	virtio_init(current_vm, child_cdrom, child_disks, child_taps);
+
+	/*
+	 * Init QEMU fw_cfg interface. Must be done last for pci hardware
+	 * detection.
+	 */
+	fw_cfg_init(vmc);
+	ioports_map[FW_CFG_IO_SELECT] = vcpu_exit_fw_cfg;
+	ioports_map[FW_CFG_IO_DATA] = vcpu_exit_fw_cfg;
+	ioports_map[FW_CFG_IO_DMA_ADDR_HIGH] = vcpu_exit_fw_cfg_dma;
+	ioports_map[FW_CFG_IO_DMA_ADDR_LOW] = vcpu_exit_fw_cfg_dma;
 }
+
 /*
  * restore_emulated_hw
  *