diff --git a/arch/x86/pci_cfg.c b/arch/x86/pci_cfg.c
new file mode 100644
index 00000000..c600c480
--- /dev/null
+++ b/arch/x86/pci_cfg.c
@@ -0,0 +1,28 @@
+/*
+ * Copyright © 2021 Amazon.com, Inc. or its affiliates.
+ * 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 COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER 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 <pci_cfg.h>
+
+/* Lock to synchronize PCI config data and address IO ports */
+spinlock_t pci_cfg_lock = SPINLOCK_INIT;
diff --git a/include/arch/x86/pci_cfg.h b/include/arch/x86/pci_cfg.h
index 843a4c3a..0614c7fd 100644
--- a/include/arch/x86/pci_cfg.h
+++ b/include/arch/x86/pci_cfg.h
@@ -27,10 +27,13 @@
 
 #include <ktf.h>
 #include <lib.h>
+#include <spinlock.h>
 
 #define PCI_IO_PORT_ADDRESS 0xcf8
 #define PCI_IO_PORT_DATA    0xcfc
 
+extern spinlock_t pci_cfg_lock;
+
 union pci_cfg_addr {
     struct {
         uint32_t zero : 2, reg : 6, fn : 3, dev : 5, bus : 8, rsvd : 7, ecsm : 1;
@@ -56,42 +59,79 @@ static inline void pci_cfg_set_addr(uint8_t bus, uint8_t dev, uint8_t func, uint
     addr.fn = func;
     addr.dev = dev;
     addr.bus = bus;
+    addr.ecsm = 1;
 
     outd(PCI_IO_PORT_ADDRESS, addr.val);
 }
 
 static inline uint8_t pci_cfg_read8(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg) {
+    uint8_t ret;
+
+    spin_lock(&pci_cfg_lock);
+
     pci_cfg_set_addr(bus, dev, func, reg);
-    return inb(PCI_IO_PORT_DATA);
+    ret = inb(PCI_IO_PORT_DATA);
+
+    spin_unlock(&pci_cfg_lock);
+
+    return ret;
 }
 
 static inline void pci_cfg_write8(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg,
                                   uint8_t value) {
+    spin_lock(&pci_cfg_lock);
+
     pci_cfg_set_addr(bus, dev, func, reg);
     outb(PCI_IO_PORT_DATA, value);
+
+    spin_unlock(&pci_cfg_lock);
 }
 
 static inline uint16_t pci_cfg_read16(uint8_t bus, uint8_t dev, uint8_t func,
                                       uint8_t reg) {
+    uint16_t ret;
+
+    spin_lock(&pci_cfg_lock);
+
     pci_cfg_set_addr(bus, dev, func, reg);
-    return inw(PCI_IO_PORT_DATA);
+    ret = inw(PCI_IO_PORT_DATA);
+
+    spin_unlock(&pci_cfg_lock);
+
+    return ret;
 }
 
 static inline void pci_cfg_write16(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg,
                                    uint16_t value) {
+    spin_lock(&pci_cfg_lock);
+
     pci_cfg_set_addr(bus, dev, func, reg);
     outw(PCI_IO_PORT_DATA, value);
+
+    spin_unlock(&pci_cfg_lock);
 }
 
 static inline uint32_t pci_cfg_read(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg) {
+    uint32_t ret;
+
+    spin_lock(&pci_cfg_lock);
+
     pci_cfg_set_addr(bus, dev, func, reg);
-    return ind(PCI_IO_PORT_DATA);
+    ret = ind(PCI_IO_PORT_DATA);
+
+    spin_unlock(&pci_cfg_lock);
+
+    return ret;
 }
 
 static inline void pci_cfg_write(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg,
                                  uint32_t value) {
+    spin_lock(&pci_cfg_lock);
+
     pci_cfg_set_addr(bus, dev, func, reg);
     outd(PCI_IO_PORT_DATA, value);
+
+    spin_unlock(&pci_cfg_lock);
 }
 
 /* External declarations */