From: Rakesh Jeyasingh <rakeshjb...@gmail.com>
The GT-64120 PCI controller requires special handling where:
1. Host bridge(bus 0 ,device 0) must never be byte-swapped
2. Other devices follow MByteSwap bit in GT_PCI0_CMD
The previous implementation incorrectly swapped all accesses, breaking
host bridge detection (lspci -d 11ab:4620).
Changes made:
1. Removed gt64120_update_pci_cfgdata_mapping() and moved data_mem
initialization
to gt64120_realize() for cleaner setup
2. Implemented custom read/write handlers that:
- Preserve host bridge accesses (extract32(config_reg,11,13)==0)
- apply swapping only for non-bridge devices in big-endian mode
Fixes: 145e2198 ("hw/mips/gt64xxx_pci: Endian-swap using PCI_HOST_BRIDGE
MemoryRegionOps")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2826
Signed-off-by: Rakesh Jeyasingh <rakeshjb...@gmail.com>
Tested-by: Thomas Huth <th...@redhat.com>
Link: https://lore.kernel.org/r/20250429170354.150581-2-rakeshjb...@gmail.com
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
hw/pci-host/gt64120.c | 82 +++++++++++++++++++++++++------------------
1 file changed, 48 insertions(+), 34 deletions(-)
diff --git a/hw/pci-host/gt64120.c b/hw/pci-host/gt64120.c
index 56a6ef93b7a..b12a25696c4 100644
--- a/hw/pci-host/gt64120.c
+++ b/hw/pci-host/gt64120.c
@@ -320,38 +320,6 @@ static void gt64120_isd_mapping(GT64120State *s)
memory_region_transaction_commit();
}
-static void gt64120_update_pci_cfgdata_mapping(GT64120State *s)
-{
- /* Indexed on MByteSwap bit, see Table 158: PCI_0 Command, Offset: 0xc00 */
- static const MemoryRegionOps *pci_host_data_ops[] = {
- &pci_host_data_be_ops, &pci_host_data_le_ops
- };
- PCIHostState *phb = PCI_HOST_BRIDGE(s);
-
- memory_region_transaction_begin();
-
- /*
- * The setting of the MByteSwap bit and MWordSwap bit in the PCI Internal
- * Command Register determines how data transactions from the CPU to/from
- * PCI are handled along with the setting of the Endianness bit in the CPU
- * Configuration Register. See:
- * - Table 16: 32-bit PCI Transaction Endianness
- * - Table 158: PCI_0 Command, Offset: 0xc00
- */
-
- if (memory_region_is_mapped(&phb->data_mem)) {
- memory_region_del_subregion(&s->ISD_mem, &phb->data_mem);
- object_unparent(OBJECT(&phb->data_mem));
- }
- memory_region_init_io(&phb->data_mem, OBJECT(phb),
- pci_host_data_ops[s->regs[GT_PCI0_CMD] & 1],
- s, "pci-conf-data", 4);
- memory_region_add_subregion_overlap(&s->ISD_mem, GT_PCI0_CFGDATA << 2,
- &phb->data_mem, 1);
-
- memory_region_transaction_commit();
-}
-
static void gt64120_pci_mapping(GT64120State *s)
{
memory_region_transaction_begin();
@@ -645,7 +613,6 @@ static void gt64120_writel(void *opaque, hwaddr addr,
case GT_PCI0_CMD:
case GT_PCI1_CMD:
s->regs[saddr] = val & 0x0401fc0f;
- gt64120_update_pci_cfgdata_mapping(s);
break;
case GT_PCI0_TOR:
case GT_PCI0_BS_SCS10:
@@ -1024,6 +991,48 @@ static const MemoryRegionOps isd_mem_ops = {
},
};
+static bool bswap(const GT64120State *s)
+{
+ PCIHostState *phb = PCI_HOST_BRIDGE(s);
+ /*check for bus == 0 && device == 0, Bits 11:15 = Device , Bits 16:23 =
Bus*/
+ bool is_phb_dev0 = extract32(phb->config_reg, 11, 13) == 0;
+ bool le_mode = FIELD_EX32(s->regs[GT_PCI0_CMD], GT_PCI0_CMD, MByteSwap);
+ /* Only swap for non-bridge devices in big-endian mode */
+ return !le_mode && !is_phb_dev0;
+}
+
+static uint64_t gt64120_pci_data_read(void *opaque, hwaddr addr, unsigned size)
+{
+ GT64120State *s = opaque;
+ uint32_t val = pci_host_data_le_ops.read(opaque, addr, size);
+
+ if (bswap(s)) {
+ val = bswap32(val);
+ }
+ return val;
+}
+
+static void gt64120_pci_data_write(void *opaque, hwaddr addr,
+ uint64_t val, unsigned size)
+{
+ GT64120State *s = opaque;
+
+ if (bswap(s)) {
+ val = bswap32(val);
+ }
+ pci_host_data_le_ops.write(opaque, addr, val, size);
+}
+
+static const MemoryRegionOps gt64120_pci_data_ops = {
+ .read = gt64120_pci_data_read,
+ .write = gt64120_pci_data_write,
+ .endianness = DEVICE_LITTLE_ENDIAN,
+ .valid = {
+ .min_access_size = 4,
+ .max_access_size = 4,
+ },
+};
+
static void gt64120_reset(DeviceState *dev)
{
GT64120State *s = GT64120_PCI_HOST_BRIDGE(dev);
@@ -1178,7 +1187,6 @@ static void gt64120_reset(DeviceState *dev)
gt64120_isd_mapping(s);
gt64120_pci_mapping(s);
- gt64120_update_pci_cfgdata_mapping(s);
}
static void gt64120_realize(DeviceState *dev, Error **errp)
@@ -1202,6 +1210,12 @@ static void gt64120_realize(DeviceState *dev, Error
**errp)
memory_region_add_subregion_overlap(&s->ISD_mem, GT_PCI0_CFGADDR << 2,
&phb->conf_mem, 1);
+ memory_region_init_io(&phb->data_mem, OBJECT(phb),
+ >64120_pci_data_ops,
+ s, "pci-conf-data", 4);
+ memory_region_add_subregion_overlap(&s->ISD_mem, GT_PCI0_CFGDATA << 2,
+ &phb->data_mem, 1);
+
/*
* The whole address space decoded by the GT-64120A doesn't generate
--
2.49.0
