diff --git a/hw/pcie_regs.h b/hw/pcie_regs.h
new file mode 100644
index 0000000..3461a1b
--- /dev/null
+++ b/hw/pcie_regs.h
@@ -0,0 +1,154 @@
+/*
+ * constants for pcie configurations space from pci express spec.
+ *
+ * TODO:
+ * Those constants and macros should go to Linux pci_regs.h
+ * Once they're merged, they will go away.
+ */
+#ifndef QEMU_PCIE_REGS_H
+#define QEMU_PCIE_REGS_H
+
+
+/* express capability */
+
+#define PCI_EXP_VER2_SIZEOF             0x3c /* express capability of ver. 2 */
+#define PCI_EXT_CAP_VER_SHIFT           16
+#define PCI_EXT_CAP_NEXT_SHIFT          20
+#define PCI_EXT_CAP_NEXT_MASK           (0xffc << PCI_EXT_CAP_NEXT_SHIFT)
+
+#define PCI_EXT_CAP(id, ver, next)                                      \
+    ((id) |                                                             \
+     ((ver) << PCI_EXT_CAP_VER_SHIFT) |                                 \
+     ((next) << PCI_EXT_CAP_NEXT_SHIFT))
+
+#define PCI_EXT_CAP_ALIGN               4
+#define PCI_EXT_CAP_ALIGNUP(x)                                  \
+    (((x) + PCI_EXT_CAP_ALIGN - 1) & ~(PCI_EXT_CAP_ALIGN - 1))
+
+/* PCI_EXP_FLAGS */
+#define PCI_EXP_FLAGS_VER2              2 /* for now, supports only ver. 2 */
+#define PCI_EXP_FLAGS_IRQ_SHIFT         (ffs(PCI_EXP_FLAGS_IRQ) - 1)
+#define PCI_EXP_FLAGS_TYPE_SHIFT        (ffs(PCI_EXP_FLAGS_TYPE) - 1)
+
+
+/* PCI_EXP_LINK{CAP, STA} */
+/* link speed */
+#define PCI_EXP_LNK_LS_25               1
+
+#define PCI_EXP_LNK_MLW_SHIFT           (ffs(PCI_EXP_LNKCAP_MLW) - 1)
+#define PCI_EXP_LNK_MLW_1               (1 << PCI_EXP_LNK_MLW_SHIFT)
+
+/* PCI_EXP_LINKCAP */
+#define PCI_EXP_LNKCAP_ASPMS_SHIFT      (ffs(PCI_EXP_LNKCAP_ASPMS) - 1)
+#define PCI_EXP_LNKCAP_ASPMS_0S         (1 << PCI_EXP_LNKCAP_ASPMS_SHIFT)
+
+#define PCI_EXP_LNKCAP_PN_SHIFT         (ffs(PCI_EXP_LNKCAP_PN) - 1)
+
+#define PCI_EXP_SLTCAP_PSN_SHIFT        (ffs(PCI_EXP_SLTCAP_PSN) - 1)
+
+#define PCI_EXP_SLTCTL_IND_RESERVED     0x0
+#define PCI_EXP_SLTCTL_IND_ON           0x1
+#define PCI_EXP_SLTCTL_IND_BLINK        0x2
+#define PCI_EXP_SLTCTL_IND_OFF          0x3
+#define PCI_EXP_SLTCTL_AIC_SHIFT        (ffs(PCI_EXP_SLTCTL_AIC) - 1)
+#define PCI_EXP_SLTCTL_AIC_OFF                          \
+    (PCI_EXP_SLTCTL_IND_OFF << PCI_EXP_SLTCTL_AIC_SHIFT)
+
+#define PCI_EXP_SLTCTL_PIC_SHIFT        (ffs(PCI_EXP_SLTCTL_PIC) - 1)
+#define PCI_EXP_SLTCTL_PIC_OFF                          \
+    (PCI_EXP_SLTCTL_IND_OFF << PCI_EXP_SLTCTL_PIC_SHIFT)
+
+#define PCI_EXP_SLTCTL_SUPPORTED        \
+            (PCI_EXP_SLTCTL_ABPE |      \
+             PCI_EXP_SLTCTL_PDCE |      \
+             PCI_EXP_SLTCTL_CCIE |      \
+             PCI_EXP_SLTCTL_HPIE |      \
+             PCI_EXP_SLTCTL_AIC |       \
+             PCI_EXP_SLTCTL_PCC |       \
+             PCI_EXP_SLTCTL_EIC)
+
+#define PCI_EXP_DEVCAP2_EFF             0x100000
+#define PCI_EXP_DEVCAP2_EETLPP          0x200000
+
+#define PCI_EXP_DEVCTL2_EETLPPB         0x80
+
+/* ARI */
+#define PCI_ARI_VER                     1
+#define PCI_ARI_SIZEOF                  8
+
+/* AER */
+#define PCI_ERR_VER                     2
+#define PCI_ERR_SIZEOF                  0x48
+
+#define PCI_ERR_UNC_SDN                 0x00000020      /* surprise down */
+#define PCI_ERR_UNC_ACSV                0x00200000      /* ACS Violation */
+#define PCI_ERR_UNC_INTN                0x00400000      /* Internal Error */
+#define PCI_ERR_UNC_MCBTLP              0x00800000      /* MC Blcoked TLP */
+#define PCI_ERR_UNC_ATOP_EBLOCKED       0x01000000      /* atomic op egress blocked */
+#define PCI_ERR_UNC_TLP_PRF_BLOCKED     0x02000000      /* TLP Prefix Blocked */
+#define PCI_ERR_COR_ADV_NONFATAL        0x00002000      /* Advisory Non-Fatal */
+#define PCI_ERR_COR_INTERNAL            0x00004000      /* Corrected Internal */
+#define PCI_ERR_COR_HL_OVERFLOW         0x00008000      /* Header Long Overflow */
+#define PCI_ERR_CAP_FEP_MASK            0x0000001f
+#define PCI_ERR_CAP_MHRC                0x00000200
+#define PCI_ERR_CAP_MHRE                0x00000400
+#define PCI_ERR_CAP_TLP                 0x00000800
+
+#define PCI_ERR_TLP_PREFIX_LOG          0x38
+
+#define PCI_SEC_STATUS_RCV_SYSTEM_ERROR         0x4000
+
+/* aer root error command/status */
+#define PCI_ERR_ROOT_CMD_EN_MASK        (PCI_ERR_ROOT_CMD_COR_EN |      \
+                                         PCI_ERR_ROOT_CMD_NONFATAL_EN | \
+                                         PCI_ERR_ROOT_CMD_FATAL_EN)
+
+#define PCI_ERR_ROOT_IRQ_MAX            32
+#define PCI_ERR_ROOT_IRQ                0xf8000000
+#define PCI_ERR_ROOT_IRQ_SHIFT          (ffs(PCI_ERR_ROOT_IRQ) - 1)
+#define PCI_ERR_ROOT_STATUS_REPORT_MASK (PCI_ERR_ROOT_COR_RCV |         \
+                                         PCI_ERR_ROOT_MULTI_COR_RCV |   \
+                                         PCI_ERR_ROOT_UNCOR_RCV |       \
+                                         PCI_ERR_ROOT_MULTI_UNCOR_RCV | \
+                                         PCI_ERR_ROOT_FIRST_FATAL |     \
+                                         PCI_ERR_ROOT_NONFATAL_RCV |    \
+                                         PCI_ERR_ROOT_FATAL_RCV)
+
+#define PCI_ERR_UNC_SUPPORTED           (PCI_ERR_UNC_DLP |              \
+                                         PCI_ERR_UNC_SDN |              \
+                                         PCI_ERR_UNC_POISON_TLP |       \
+                                         PCI_ERR_UNC_FCP |              \
+                                         PCI_ERR_UNC_COMP_TIME |        \
+                                         PCI_ERR_UNC_COMP_ABORT |       \
+                                         PCI_ERR_UNC_UNX_COMP |         \
+                                         PCI_ERR_UNC_RX_OVER |          \
+                                         PCI_ERR_UNC_MALF_TLP |         \
+                                         PCI_ERR_UNC_ECRC |             \
+                                         PCI_ERR_UNC_UNSUP |            \
+                                         PCI_ERR_UNC_ACSV |             \
+                                         PCI_ERR_UNC_INTN |             \
+                                         PCI_ERR_UNC_MCBTLP |           \
+                                         PCI_ERR_UNC_ATOP_EBLOCKED |    \
+                                         PCI_ERR_UNC_TLP_PRF_BLOCKED)
+
+#define PCI_ERR_UNC_SEVERITY_DEFAULT    (PCI_ERR_UNC_DLP |              \
+                                         PCI_ERR_UNC_SDN |              \
+                                         PCI_ERR_UNC_FCP |              \
+                                         PCI_ERR_UNC_RX_OVER |          \
+                                         PCI_ERR_UNC_MALF_TLP |         \
+                                         PCI_ERR_UNC_INTN)
+
+#define PCI_ERR_COR_SUPPORTED           (PCI_ERR_COR_RCVR |             \
+                                         PCI_ERR_COR_BAD_TLP |          \
+                                         PCI_ERR_COR_BAD_DLLP |         \
+                                         PCI_ERR_COR_REP_ROLL |         \
+                                         PCI_ERR_COR_REP_TIMER |        \
+                                         PCI_ERR_COR_ADV_NONFATAL |     \
+                                         PCI_ERR_COR_INTERNAL |         \
+                                         PCI_ERR_COR_HL_OVERFLOW)
+
+#define PCI_ERR_COR_MASK_DEFAULT        (PCI_ERR_COR_ADV_NONFATAL |     \
+                                         PCI_ERR_COR_INTERNAL |         \
+                                         PCI_ERR_COR_HL_OVERFLOW)
+
+#endif /* QEMU_PCIE_REGS_H */
