diff --git a/xen/arch/x86/pv/ro-page-fault.c b/xen/arch/x86/pv/ro-page-fault.c
index e70e09a6a6..c10541709e 100644
--- a/xen/arch/x86/pv/ro-page-fault.c
+++ b/xen/arch/x86/pv/ro-page-fault.c
@@ -331,9 +331,7 @@ static int cf_check mmcfg_intercept_write(
     offset &= 0xfff;
     if ( pci_conf_write_intercept(mmio_ctxt->sbdf.seg, mmio_ctxt->sbdf.bdf,
                                   offset, bytes, p_data) >= 0 )
-        pci_mmcfg_write(mmio_ctxt->sbdf.seg, mmio_ctxt->sbdf.bus,
-                        mmio_ctxt->sbdf.devfn, offset, bytes,
-                        *(uint32_t *)p_data);
+        pci_mmcfg_write(mmio_ctxt->sbdf, offset, bytes, *(uint32_t *)p_data);
 
     return X86EMUL_OKAY;
 }
diff --git a/xen/arch/x86/x86_64/mmconfig_64.c b/xen/arch/x86/x86_64/mmconfig_64.c
index 91b1a398e6..6477bf8b44 100644
--- a/xen/arch/x86/x86_64/mmconfig_64.c
+++ b/xen/arch/x86/x86_64/mmconfig_64.c
@@ -55,19 +55,18 @@ static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus, unsigned i
      return addr + ((bus << 20) | (devfn << 12));
 }
 
-int pci_mmcfg_read(unsigned int seg, unsigned int bus,
-              unsigned int devfn, int reg, int len, u32 *value)
+int pci_mmcfg_read(
+    pci_sbdf_t sbdf, unsigned int reg, unsigned int len, uint32_t *value)
 {
     char __iomem *addr;
 
     /* Why do we have this when nobody checks it. How about a BUG()!? -AK */
-    if (unlikely((bus > 255) || (devfn > 255) ||
-                 (reg + len > PCI_CFG_SPACE_EXP_SIZE))) {
+    if (unlikely(reg + len > PCI_CFG_SPACE_EXP_SIZE)) {
 err:        *value = -1;
         return -EINVAL;
     }
 
-    addr = pci_dev_base(seg, bus, devfn);
+    addr = pci_dev_base(sbdf.seg, sbdf.bus, sbdf.devfn);
     if (!addr)
         goto err;
 
@@ -86,17 +85,16 @@ err:        *value = -1;
     return 0;
 }
 
-int pci_mmcfg_write(unsigned int seg, unsigned int bus,
-               unsigned int devfn, int reg, int len, u32 value)
+int pci_mmcfg_write(
+    pci_sbdf_t sbdf, unsigned int reg, unsigned int len, uint32_t value)
 {
     char __iomem *addr;
 
     /* Why do we have this when nobody checks it. How about a BUG()!? -AK */
-    if (unlikely((bus > 255) || (devfn > 255) ||
-                 (reg + len > PCI_CFG_SPACE_EXP_SIZE)))
+    if (unlikely(reg + len > PCI_CFG_SPACE_EXP_SIZE))
         return -EINVAL;
 
-    addr = pci_dev_base(seg, bus, devfn);
+    addr = pci_dev_base(sbdf.seg, sbdf.bus, sbdf.devfn);
     if (!addr)
         return -EINVAL;
 
diff --git a/xen/arch/x86/x86_64/pci.c b/xen/arch/x86/x86_64/pci.c
index 6298141c3c..970c010e12 100644
--- a/xen/arch/x86/x86_64/pci.c
+++ b/xen/arch/x86/x86_64/pci.c
@@ -17,7 +17,7 @@ uint8_t pci_conf_read8(pci_sbdf_t sbdf, unsigned int reg)
 
     if ( sbdf.seg || reg > 255 )
     {
-        pci_mmcfg_read(sbdf.seg, sbdf.bus, sbdf.devfn, reg, 1, &value);
+        pci_mmcfg_read(sbdf, reg, 1, &value);
         return value;
     }
 
@@ -30,7 +30,7 @@ uint16_t pci_conf_read16(pci_sbdf_t sbdf, unsigned int reg)
     {
         uint32_t value;
 
-        pci_mmcfg_read(sbdf.seg, sbdf.bus, sbdf.devfn, reg, 2, &value);
+        pci_mmcfg_read(sbdf, reg, 2, &value);
         return value;
     }
 
@@ -43,7 +43,7 @@ uint32_t pci_conf_read32(pci_sbdf_t sbdf, unsigned int reg)
     {
         uint32_t value;
 
-        pci_mmcfg_read(sbdf.seg, sbdf.bus, sbdf.devfn, reg, 4, &value);
+        pci_mmcfg_read(sbdf, reg, 4, &value);
         return value;
     }
 
@@ -53,7 +53,7 @@ uint32_t pci_conf_read32(pci_sbdf_t sbdf, unsigned int reg)
 void pci_conf_write8(pci_sbdf_t sbdf, unsigned int reg, uint8_t data)
 {
     if ( sbdf.seg || reg > 255 )
-        pci_mmcfg_write(sbdf.seg, sbdf.bus, sbdf.devfn, reg, 1, data);
+        pci_mmcfg_write(sbdf, reg, 1, data);
     else
         pci_conf_write(PCI_CONF_ADDRESS(sbdf, reg), reg & 3, 1, data);
 }
@@ -61,7 +61,7 @@ void pci_conf_write8(pci_sbdf_t sbdf, unsigned int reg, uint8_t data)
 void pci_conf_write16(pci_sbdf_t sbdf, unsigned int reg, uint16_t data)
 {
     if ( sbdf.seg || reg > 255 || !IS_ALIGNED(reg, 2) )
-        pci_mmcfg_write(sbdf.seg, sbdf.bus, sbdf.devfn, reg, 2, data);
+        pci_mmcfg_write(sbdf, reg, 2, data);
     else
         pci_conf_write(PCI_CONF_ADDRESS(sbdf, reg), reg & 2, 2, data);
 }
@@ -69,7 +69,7 @@ void pci_conf_write16(pci_sbdf_t sbdf, unsigned int reg, uint16_t data)
 void pci_conf_write32(pci_sbdf_t sbdf, unsigned int reg, uint32_t data)
 {
     if ( sbdf.seg || reg > 255 || !IS_ALIGNED(reg, 4) )
-        pci_mmcfg_write(sbdf.seg, sbdf.bus, sbdf.devfn, reg, 4, data);
+        pci_mmcfg_write(sbdf, reg, 4, data);
     else
         pci_conf_write(PCI_CONF_ADDRESS(sbdf, reg), 0, 4, data);
 }
diff --git a/xen/include/xen/pci.h b/xen/include/xen/pci.h
index ade882caee..b7a35371a7 100644
--- a/xen/include/xen/pci.h
+++ b/xen/include/xen/pci.h
@@ -258,10 +258,10 @@ void pci_conf_write16(pci_sbdf_t sbdf, unsigned int reg, uint16_t data);
 void pci_conf_write32(pci_sbdf_t sbdf, unsigned int reg, uint32_t data);
 uint32_t pci_conf_read(uint32_t cf8, uint8_t offset, uint8_t bytes);
 void pci_conf_write(uint32_t cf8, uint8_t offset, uint8_t bytes, uint32_t data);
-int pci_mmcfg_read(unsigned int seg, unsigned int bus,
-                   unsigned int devfn, int reg, int len, u32 *value);
-int pci_mmcfg_write(unsigned int seg, unsigned int bus,
-                    unsigned int devfn, int reg, int len, u32 value);
+int pci_mmcfg_read(
+    pci_sbdf_t sbdf, unsigned int reg, unsigned int len, uint32_t *value);
+int pci_mmcfg_write(
+    pci_sbdf_t sbdf, unsigned int reg, unsigned int len, uint32_t value);
 unsigned int pci_find_cap_offset(pci_sbdf_t sbdf, unsigned int cap);
 unsigned int pci_find_next_cap_ttl(pci_sbdf_t sbdf, unsigned int pos,
                                    const unsigned int caps[], unsigned int n,