[PATCH v1 1/1] hw/pci: Disable PCI_ERR_UNCOR_MASK register for machine type < 8.0

[Leonardo Bras <leobras@redhat.com>]

Since it's implementation on v8.0.0-rc0, having the PCI_ERR_UNCOR_MASK
set for machine types < 8.0 will cause migration to fail if the target
QEMU version is < 8.0.0 :

qemu-system-x86_64: get_pci_config_device: Bad config data: i=0x10a read: 40 device: 0 cmask: ff wmask: 0 w1cmask:0
qemu-system-x86_64: Failed to load PCIDevice:config
qemu-system-x86_64: Failed to load e1000e:parent_obj
qemu-system-x86_64: error while loading state for instance 0x0 of device '0000:00:02.0/e1000e'
qemu-system-x86_64: load of migration failed: Invalid argument

The above test migrated a 7.2 machine type from QEMU master to QEMU 7.2.0,
with this cmdline:

./qemu-system-x86_64 -M pc-q35-7.2 [-incoming XXX]

In order to fix this, property x-pcie-err-unc-mask was introduced to
control when PCI_ERR_UNCOR_MASK is enabled. This property is enabled by
default, but is disabled if machine type <= 7.2.

Fixes: 010746ae1d ("hw/pci/aer: Implement PCI_ERR_UNCOR_MASK register")
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Leonardo Bras <leobras@redhat.com>
---
 include/hw/pci/pci.h |  2 ++
 hw/core/machine.c    |  1 +
 hw/pci/pci.c         |  2 ++
 hw/pci/pcie_aer.c    | 11 +++++++----
 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index 935b4b91b4..e6d0574a29 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -207,6 +207,8 @@ enum {
     QEMU_PCIE_EXTCAP_INIT = (1 << QEMU_PCIE_EXTCAP_INIT_BITNR),
 #define QEMU_PCIE_CXL_BITNR 10
     QEMU_PCIE_CAP_CXL = (1 << QEMU_PCIE_CXL_BITNR),
+#define QEMU_PCIE_ERR_UNC_MASK_BITNR 11
+    QEMU_PCIE_ERR_UNC_MASK = (1 << QEMU_PCIE_ERR_UNC_MASK_BITNR),
 };
 
 typedef struct PCIINTxRoute {
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 47a34841a5..07f763eb2e 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -48,6 +48,7 @@ GlobalProperty hw_compat_7_2[] = {
     { "e1000e", "migrate-timadj", "off" },
     { "virtio-mem", "x-early-migration", "false" },
     { "migration", "x-preempt-pre-7-2", "true" },
+    { TYPE_PCI_DEVICE, "x-pcie-err-unc-mask", "off" },
 };
 const size_t hw_compat_7_2_len = G_N_ELEMENTS(hw_compat_7_2);
 
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 8a87ccc8b0..5153ad63d6 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -79,6 +79,8 @@ static Property pci_props[] = {
     DEFINE_PROP_STRING("failover_pair_id", PCIDevice,
                        failover_pair_id),
     DEFINE_PROP_UINT32("acpi-index",  PCIDevice, acpi_index, 0),
+    DEFINE_PROP_BIT("x-pcie-err-unc-mask", PCIDevice, cap_present,
+                    QEMU_PCIE_ERR_UNC_MASK_BITNR, true),
     DEFINE_PROP_END_OF_LIST()
 };
 
diff --git a/hw/pci/pcie_aer.c b/hw/pci/pcie_aer.c
index 103667c368..374d593ead 100644
--- a/hw/pci/pcie_aer.c
+++ b/hw/pci/pcie_aer.c
@@ -112,10 +112,13 @@ int pcie_aer_init(PCIDevice *dev, uint8_t cap_ver, uint16_t offset,
 
     pci_set_long(dev->w1cmask + offset + PCI_ERR_UNCOR_STATUS,
                  PCI_ERR_UNC_SUPPORTED);
-    pci_set_long(dev->config + offset + PCI_ERR_UNCOR_MASK,
-                 PCI_ERR_UNC_MASK_DEFAULT);
-    pci_set_long(dev->wmask + offset + PCI_ERR_UNCOR_MASK,
-                 PCI_ERR_UNC_SUPPORTED);
+
+    if (dev->cap_present & QEMU_PCIE_ERR_UNC_MASK) {
+        pci_set_long(dev->config + offset + PCI_ERR_UNCOR_MASK,
+                     PCI_ERR_UNC_MASK_DEFAULT);
+        pci_set_long(dev->wmask + offset + PCI_ERR_UNCOR_MASK,
+                     PCI_ERR_UNC_SUPPORTED);
+    }
 
     pci_set_long(dev->config + offset + PCI_ERR_UNCOR_SEVER,
                  PCI_ERR_UNC_SEVERITY_DEFAULT);
-- 
2.40.0