From 4565917bb034479a29c04f0b44124e7f61585ccf Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Tue, 29 Aug 2023 16:14:29 -0400 Subject: [PATCH] pci: SLT must be RO current code sets PCI_SEC_LATENCY_TIMER to RW, but for pcie to pcie bridges it must be RO 0 according to pci express spec which says: This register does not apply to PCI Express. It must be read-only and hardwired to 00h. For PCI Express to PCI/PCI-X Bridges, refer to the [PCIe-to-PCI-PCI-X-Bridge] for requirements for this register. also, fix typo in comment where it's made writeable - this typo is likely what prevented us noticing we violate this requirement in the 1st place. Reported-by: Marcin Juszkiewicz Message-Id: Tested-by: Marcin Juszkiewicz Signed-off-by: Michael S. Tsirkin --- hw/core/machine.c | 5 ++++- hw/pci/pci.c | 2 +- hw/pci/pci_bridge.c | 14 ++++++++++++++ include/hw/pci/pci_bridge.h | 3 +++ 4 files changed, 22 insertions(+), 2 deletions(-) diff --git a/hw/core/machine.c b/hw/core/machine.c index cb38b8cf4c..9ae8f793ae 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -32,6 +32,7 @@ #include "qemu/error-report.h" #include "sysemu/qtest.h" #include "hw/pci/pci.h" +#include "hw/pci/pci_bridge.h" #include "hw/mem/nvdimm.h" #include "migration/global_state.h" #include "migration/vmstate.h" @@ -40,7 +41,9 @@ #include "hw/virtio/virtio-pci.h" #include "hw/virtio/virtio-net.h" -GlobalProperty hw_compat_8_1[] = {}; +GlobalProperty hw_compat_8_1[] = { + { TYPE_PCI_BRIDGE, "x-pci-express-writeable-slt-bug", "true" }, +}; const size_t hw_compat_8_1_len = G_N_ELEMENTS(hw_compat_8_1); GlobalProperty hw_compat_8_0[] = { diff --git a/hw/pci/pci.c b/hw/pci/pci.c index 881d774fb6..b0d21bf43a 100644 --- a/hw/pci/pci.c +++ b/hw/pci/pci.c @@ -893,7 +893,7 @@ static void pci_init_w1cmask(PCIDevice *dev) static void pci_init_mask_bridge(PCIDevice *d) { /* PCI_PRIMARY_BUS, PCI_SECONDARY_BUS, PCI_SUBORDINATE_BUS and - PCI_SEC_LETENCY_TIMER */ + PCI_SEC_LATENCY_TIMER */ memset(d->wmask + PCI_PRIMARY_BUS, 0xff, 4); /* base and limit */ diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c index e7b9345615..6a4e38856d 100644 --- a/hw/pci/pci_bridge.c +++ b/hw/pci/pci_bridge.c @@ -38,6 +38,7 @@ #include "qapi/error.h" #include "hw/acpi/acpi_aml_interface.h" #include "hw/acpi/pci.h" +#include "hw/qdev-properties.h" /* PCI bridge subsystem vendor ID helper functions */ #define PCI_SSVID_SIZEOF 8 @@ -385,6 +386,11 @@ void pci_bridge_initfn(PCIDevice *dev, const char *typename) pci_bridge_region_init(br); QLIST_INIT(&sec_bus->child); QLIST_INSERT_HEAD(&parent->child, sec_bus, sibling); + + /* For express secondary buses, secondary latency timer is RO 0 */ + if (pci_bus_is_express(sec_bus) && !br->pcie_writeable_slt_bug) { + dev->wmask[PCI_SEC_LATENCY_TIMER] = 0; + } } /* default qdev clean up function for PCI-to-PCI bridge */ @@ -466,10 +472,18 @@ int pci_bridge_qemu_reserve_cap_init(PCIDevice *dev, int cap_offset, return 0; } +static Property pci_bridge_properties[] = { + DEFINE_PROP_BOOL("x-pci-express-writeable-slt-bug", PCIBridge, + pcie_writeable_slt_bug, false), + DEFINE_PROP_END_OF_LIST(), +}; + static void pci_bridge_class_init(ObjectClass *klass, void *data) { AcpiDevAmlIfClass *adevc = ACPI_DEV_AML_IF_CLASS(klass); + DeviceClass *k = DEVICE_CLASS(klass); + device_class_set_props(k, pci_bridge_properties); adevc->build_dev_aml = build_pci_bridge_aml; } diff --git a/include/hw/pci/pci_bridge.h b/include/hw/pci/pci_bridge.h index ea54a81a15..5cd452115a 100644 --- a/include/hw/pci/pci_bridge.h +++ b/include/hw/pci/pci_bridge.h @@ -77,6 +77,9 @@ struct PCIBridge { pci_map_irq_fn map_irq; const char *bus_name; + + /* SLT is RO for PCIE to PCIE bridges, but old QEMU versions had it RW */ + bool pcie_writeable_slt_bug; }; #define PCI_BRIDGE_DEV_PROP_CHASSIS_NR "chassis_nr"