bhyve: add config option to modify LPC IDs

The Intel GOP driver checks the LPC IDs to detect the platform it's
running on. The GOP driver only works on the platforms it's written for.
Maybe other Intel driver have the same behaviour. For that reason, we
should use the LPC IDs of the FreeBSD host for GPU passthrough to work
properly.

We don't know if setting different LPC IDs have any side effect.
Therefore, don't use the host LPC IDs by default on Intel system. Give
the user the opportunity to modify the LPC IDs.

Reviewed by:		jhb
MFC after:		1 week
Sponsored by:		Beckhoff Automation GmbH & Co. KG
Differential Revision:	https://reviews.freebsd.org/D28280

2 files changed, 57 insertions, 3 deletions

diff --git a/usr.sbin/bhyve/bhyve_config.5 b/usr.sbin/bhyve/bhyve_config.5
index ddfcae8c51d3..e9594d432563 100644
--- a/usr.sbin/bhyve/bhyve_config.5
+++ b/usr.sbin/bhyve/bhyve_config.5
@@ -542,6 +542,20 @@ for fwctl and
 for fwcfg.
 .It Va pc-testdev Ta bool Ta false Ta
 Enable the PC debug/test device.
+.It Va pcir.* Ta integer Ta Ta
+Values of PCI register.
+It also accepts the value
+.Ar host
+to use the pci id of the host system.
+This value is required for the Intel GOP driver to work properly.
+.Bl -column "subvendor" "Default"
+.It Sy Name Ta Sy Default
+.It Va vendor Ta 0x8086
+.It Va device Ta 0x7000
+.It Va revid Ta 0
+.It Va subvendor Ta 0
+.It Va subdevice Ta 0
+.El
 .El
 .Ss NVMe Controller Settings
 Each NVMe controller supports a single storage device.
diff --git a/usr.sbin/bhyve/pci_lpc.c b/usr.sbin/bhyve/pci_lpc.c
index ad47230c005e..3b42947369a2 100644
--- a/usr.sbin/bhyve/pci_lpc.c
+++ b/usr.sbin/bhyve/pci_lpc.c
@@ -51,6 +51,7 @@ __FBSDID("$FreeBSD$");
 #include "pci_emul.h"
 #include "pci_irq.h"
 #include "pci_lpc.h"
+#include "pci_passthru.h"
 #include "pctestdev.h"
 #include "uart_emul.h"
 
@@ -448,10 +449,35 @@ pci_lpc_read(struct pci_devinst *pi __unused, int baridx __unused,
 
 #define	LPC_DEV		0x7000
 #define	LPC_VENDOR	0x8086
+#define LPC_REVID	0x00
+#define LPC_SUBVEND_0	0x0000
+#define LPC_SUBDEV_0	0x0000
 
 static int
-pci_lpc_init(struct pci_devinst *pi, nvlist_t *nvl __unused)
+pci_lpc_get_sel(struct pcisel *const sel)
 {
+	assert(sel != NULL);
+
+	memset(sel, 0, sizeof(*sel));
+
+	for (uint8_t slot = 0; slot <= PCI_SLOTMAX; ++slot) {
+		sel->pc_dev = slot;
+		if ((read_config(sel, PCIR_CLASS, 1) == PCIC_BRIDGE) &&
+		    (read_config(sel, PCIR_SUBCLASS, 1) == PCIS_BRIDGE_ISA)) {
+			return (0);
+		}
+	}
+
+	return (-1);
+}
+
+static int
+pci_lpc_init(struct pci_devinst *pi, nvlist_t *nvl)
+{
+	struct pcisel sel = { 0 };
+	uint16_t device, subdevice, subvendor, vendor;
+	uint8_t revid;
+
 	/*
 	 * Do not allow more than one LPC bridge to be configured.
 	 */
@@ -473,11 +499,25 @@ pci_lpc_init(struct pci_devinst *pi, nvlist_t *nvl __unused)
 	if (lpc_init(pi->pi_vmctx) != 0)
 		return (-1);
 
+	if (pci_lpc_get_sel(&sel) != 0)
+		return (-1);
+
+	vendor = pci_config_read_reg(&sel, nvl, PCIR_VENDOR, 2, LPC_VENDOR);
+	device = pci_config_read_reg(&sel, nvl, PCIR_DEVICE, 2, LPC_DEV);
+	revid = pci_config_read_reg(&sel, nvl, PCIR_REVID, 1, LPC_REVID);
+	subvendor = pci_config_read_reg(&sel, nvl, PCIR_SUBVEND_0, 2,
+	    LPC_SUBVEND_0);
+	subdevice = pci_config_read_reg(&sel, nvl, PCIR_SUBDEV_0, 2,
+	    LPC_SUBDEV_0);
+
 	/* initialize config space */
-	pci_set_cfgdata16(pi, PCIR_DEVICE, LPC_DEV);
-	pci_set_cfgdata16(pi, PCIR_VENDOR, LPC_VENDOR);
+	pci_set_cfgdata16(pi, PCIR_VENDOR, vendor);
+	pci_set_cfgdata16(pi, PCIR_DEVICE, device);
 	pci_set_cfgdata8(pi, PCIR_CLASS, PCIC_BRIDGE);
 	pci_set_cfgdata8(pi, PCIR_SUBCLASS, PCIS_BRIDGE_ISA);
+	pci_set_cfgdata8(pi, PCIR_REVID, revid);
+	pci_set_cfgdata16(pi, PCIR_SUBVEND_0, subvendor);
+	pci_set_cfgdata16(pi, PCIR_SUBDEV_0, subdevice);
 
 	lpc_bridge = pi;