Users of Intel discrete graphics adapters are confused with fake information on PCIe link bandwidth (speed and size) of their GPU devices reported by sysfs and userspace tools, including our lsgpu utility. In order for the lsgpu to show correct link bandwidth information, we need to identify an upstream port of a PCIe bridge that sits on the GPU card and get that information from that port.
Since the tool uses our udev based igt_device_scan library for identifying GPU devices and printing their properties and attributes, modifications that we need apply to that library. When scanning for DRM devices and their PCI parents, the lsgpu utility requests collection of all their attributes. When running in this mode, also try to collect information about upstream ports of PCIe bridges of discrete GPU devices. Once collected, the lsgpu utility will show that information automatically while listing the devices. While IGT tests are using pciaccess library for processing PCI devices, that library requires careful handling in order to avoid collisions among multiple processes or threads potentially using it. That protection is implemented in igt_device with help of IGT exit handlers. That requires linking with full igt_core library code, while the lsgpu tool now depends neither on igt_device nor on igt_core. To keep that independence, implement the new code around libpci. With that approach, refactoring of IGT use of pciaccess is avoided. Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/10753 Signed-off-by: Janusz Krzysztofik <[email protected]> --- lib/igt_device_scan.c | 73 +++++++++++++++++++++++++++++++++++++++++-- lib/meson.build | 2 ++ meson.build | 1 + 3 files changed, 74 insertions(+), 2 deletions(-) diff --git a/lib/igt_device_scan.c b/lib/igt_device_scan.c index d3a2ebe8d2..34c7a8131b 100644 --- a/lib/igt_device_scan.c +++ b/lib/igt_device_scan.c @@ -36,6 +36,7 @@ #ifdef __linux__ #include <linux/limits.h> #endif +#include <pci/pci.h> #include <sys/stat.h> #include <sys/time.h> #include <sys/types.h> @@ -909,6 +910,27 @@ static struct igt_device *igt_device_from_syspath(const char *syspath) return NULL; } +static bool is_pcie_upstream_bridge(struct pci_dev *dev) +{ + struct pci_cap *pcie; + uint8_t type, dir; + + type = pci_read_byte(dev, PCI_HEADER_TYPE) & 0x7f; + if (type != PCI_HEADER_TYPE_BRIDGE) + return false; + + pcie = pci_find_cap(dev, PCI_CAP_ID_EXP, PCI_CAP_NORMAL); + if (!pcie) + return false; + + /* GET_REG_MASK macro borrowed from pciutils' internal bitops.h */ +#define GET_REG_MASK(reg, mask) (((reg) & (mask)) / ((mask) & ~((mask) << 1))) + dir = GET_REG_MASK(pci_read_word(dev, pcie->addr + PCI_EXP_FLAGS), PCI_EXP_FLAGS_TYPE); +#undef GET_REG_MASK + + return dir == PCI_EXP_TYPE_UPSTREAM; +} + #define RETRIES_GET_PARENT 5 static struct igt_device *find_or_add_igt_device(struct udev *udev, @@ -948,18 +970,55 @@ static struct igt_device *find_or_add_igt_device(struct udev *udev, return idev; } +static struct udev_device *get_pcie_upstream_bridge(struct udev *udev, + struct udev_device *dev) +{ + struct pci_access *pacc; + + pacc = pci_alloc(); + pci_init(pacc); + + for (dev = udev_device_get_parent(dev); dev; dev = udev_device_get_parent(dev)) { + struct pci_filter filter; + struct pci_dev *pci_dev; + const char *slot; + + slot = udev_device_get_property_value(dev, "PCI_SLOT_NAME"); + if (igt_debug_on(!slot)) + continue; + + pci_filter_init(pacc, &filter); + if (igt_debug_on(pci_filter_parse_slot(&filter, (char *)slot))) + continue; + + pci_dev = pci_get_dev(pacc, filter.domain, filter.bus, filter.slot, filter.func); + if (igt_debug_on(!pci_dev)) + continue; + + if (is_pcie_upstream_bridge(pci_dev)) + break; + } + + pci_cleanup(pacc); + + return dev; +} + /* * For each drm igt_device add or update its parent igt_device to the array. * As card/render drm devices mostly have same parent (vkms is an exception) * link to it and update corresponding drm_card / drm_render fields. + * + * If collecting all attributes and the parent is a discrete GPU then also + * add or update its bridge's upstream port. */ static void update_or_add_parent(struct udev *udev, struct udev_device *dev, struct igt_device *idev, bool limit_attrs) { - struct udev_device *parent_dev; - struct igt_device *parent_idev; + struct igt_device *parent_idev, *bridge_idev; + struct udev_device *parent_dev, *bridge_dev; const char *devname; /* @@ -979,6 +1038,16 @@ static void update_or_add_parent(struct udev *udev, parent_idev->drm_render = strdup(devname); idev->parent = parent_idev; + + if (limit_attrs || parent_idev->dev_type != DEVTYPE_DISCRETE) + return; + + bridge_dev = get_pcie_upstream_bridge(udev, parent_dev); + if (!bridge_dev) + return; + + bridge_idev = find_or_add_igt_device(udev, bridge_dev, limit_attrs); + igt_assert(bridge_idev); } static struct igt_device *duplicate_device(struct igt_device *dev) { diff --git a/lib/meson.build b/lib/meson.build index 1a569ba52a..d10e1405ac 100644 --- a/lib/meson.build +++ b/lib/meson.build @@ -139,6 +139,7 @@ lib_deps = [ libdrm, libdw, libkmod, + libpci, libudev, math, pciaccess, @@ -332,6 +333,7 @@ lib_igt_perf = declare_dependency(link_with : lib_igt_perf_build, scan_dep = [ glib, + libpci, libudev, ] diff --git a/meson.build b/meson.build index 4b2496c016..57849648a3 100644 --- a/meson.build +++ b/meson.build @@ -162,6 +162,7 @@ endif build_info += 'Valgrind annotations: @0@'.format(valgrind.found()) cairo = dependency('cairo', version : '>1.12.0', required : true) +libpci = dependency('libpci', required : true) libudev = dependency('libudev', required : true) glib = dependency('glib-2.0', required : true) -- 2.52.0
