diff --git sys/dev/pci/pci.c sys/dev/pci/pci.c
index 722db59..b4e0a88 100755
--- sys/dev/pci/pci.c
+++ sys/dev/pci/pci.c
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/malloc.h>
 #include <sys/module.h>
 #include <sys/linker.h>
+#include <sys/nv.h>
 #include <sys/fcntl.h>
 #include <sys/conf.h>
 #include <sys/kernel.h>
@@ -61,6 +62,7 @@ __FBSDID("$FreeBSD$");
 #include <dev/pci/pcireg.h>
 #include <dev/pci/pcivar.h>
 #include <dev/pci/pci_private.h>
+#include <dev/pci/pci_iov_private.h>
 
 #include <dev/usb/controller/xhcireg.h>
 #include <dev/usb/controller/ehcireg.h>
@@ -74,6 +76,11 @@ __FBSDID("$FreeBSD$");
 	(((cfg)->hdrtype == PCIM_HDRTYPE_NORMAL && reg == PCIR_BIOS) ||	\
 	 ((cfg)->hdrtype == PCIM_HDRTYPE_BRIDGE && reg == PCIR_BIOS_1))
 
+#define PCIR_IS_IOV(cfg, reg)						\
+	(((cfg)->iov != NULL) &&					\
+	 ((reg) >= (cfg)->iov->iov_pos + PCIR_SRIOV_BAR(0)) &&		\
+	 ((reg) <= (cfg)->iov->iov_pos + PCIR_SRIOV_BAR(PCIR_MAX_BAR_0)))
+
 static int		pci_has_quirk(uint32_t devid, int quirk);
 static pci_addr_t	pci_mapbase(uint64_t mapreg);
 static const char	*pci_maptype(uint64_t mapreg);
@@ -2597,7 +2604,8 @@ pci_read_bar(device_t dev, int reg, pci_addr_t *mapp, pci_addr_t *testvalp,
 	struct pci_devinfo *dinfo;
 	pci_addr_t map, testval;
 	int ln2range;
-	uint16_t cmd;
+	uint32_t restore_reg;
+	uint16_t cmd, mask;
 
 	/*
 	 * The device ROM BAR is special.  It is always a 32-bit
@@ -2627,9 +2635,18 @@ pci_read_bar(device_t dev, int reg, pci_addr_t *mapp, pci_addr_t *testvalp,
 	 * determining the BAR's length since we will be placing it in
 	 * a weird state.
 	 */
-	cmd = pci_read_config(dev, PCIR_COMMAND, 2);
-	pci_write_config(dev, PCIR_COMMAND,
-	    cmd & ~(PCI_BAR_MEM(map) ? PCIM_CMD_MEMEN : PCIM_CMD_PORTEN), 2);
+#ifdef PCI_IOV
+	if (PCIR_IS_IOV(&dinfo->cfg, reg)) {
+	    restore_reg = dinfo->cfg.iov->iov_pos + PCIR_SRIOV_CTL;
+	    mask = PCIM_SRIOV_VF_MSE;
+	} else
+#endif
+	{
+	    restore_reg = PCIR_COMMAND;
+	    mask = PCI_BAR_MEM(map) ? PCIM_CMD_MEMEN : PCIM_CMD_PORTEN;
+	}
+	cmd = pci_read_config(dev, restore_reg, 2);
+	pci_write_config(dev, restore_reg, cmd & ~mask, 2);
 
 	/*
 	 * Determine the BAR's length by writing all 1's.  The bottom
@@ -2651,7 +2668,7 @@ pci_read_bar(device_t dev, int reg, pci_addr_t *mapp, pci_addr_t *testvalp,
 	pci_write_config(dev, reg, map, 4);
 	if (ln2range == 64)
 		pci_write_config(dev, reg + 4, map >> 32, 4);
-	pci_write_config(dev, PCIR_COMMAND, cmd, 2);
+	pci_write_config(dev, restore_reg, cmd, 2);
 
 	*mapp = map;
 	*testvalp = testval;