> Subject: Re: [PATCH V2] pci: introduce static_nr to indicate domain_nr from > which IDA > > On Wed, Sep 13, 2023 at 01:24:26AM +0000, Peng Fan wrote: > > > Subject: Re: [PATCH V2] pci: introduce static_nr to indicate > > > domain_nr from which IDA > > > > > > On Tue, Aug 15, 2023 at 09:37:44AM +0800, Peng Fan (OSS) wrote: > > > > From: Peng Fan <peng.fan@xxxxxxx> > > > > > > > > When PCI node was created using an overlay and the overlay is > > > > reverted/destroyed, the "linux,pci-domain" property no longer > > > > exists, so of_get_pci_domain_nr will return failure. > > > > > > I'm not familiar with how overlays work. What's the call path where > > > the overlay is removed? I see an of_overlay_remove(), but I don't > > > see any callers except test cases. > > > > We are using an out of tree hypervisor driver: > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgith > > > ub.com%2Fsiemens%2Fjailhouse%2Fblob%2Fmaster%2Fdriver%2Fpci.c%23L > 483&d > > > ata=05%7C01%7Cpeng.fan%40nxp.com%7C1bf0364c585f42dae7f108dbb3fe > fcc4%7C > > > 686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C63830167996269745 > 6%7CUnknow > > > n%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1ha > WwiLC > > > JXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=raIsz2HIH%2FQ0nmolBBwd81 > WxQh2vmFeXN > > t3n6OIQaSU%3D&reserved=0 > > > > > > I guess the problem happens in a PCI host bridge remove path, e.g., > > > > > > pci_host_common_remove > > > pci_remove_root_bus > > > pci_bus_release_domain_nr > > > of_pci_bus_release_domain_nr > > > > > > But I don't know how that's related to the overlay removal. > > > > When the overlay node got removed, the device removal will be invoked > > and the domain number indicated by linux,pci-domain should also get freed. > > > > But actually the domain number not got freed because of bug as this > > patch shows. "of_pci_bus_release_domain_nr will actually use the > > dynamic IDA, even if the IDA was allocated in static IDA." > > > > So after the overlay node got destroyed and our test recreate the > > overlay node with same domain number, issue triggered, the device > > could not be created. > > > > > Is this an ordering issue? It seems possibly problematic that the > > > OF overlay is destroyed before the device it describes (e.g., the > > > host > > > > No. it is "of_pci_bus_release_domain_nr will actually use the dynamic > > IDA, even if the IDA was allocated in static IDA " > > Yes, that's the *symptom*, to be sure. My question was why the overlay was > removed before the host bridge. I am not sure. I added a dump_stack, would this help to understand? root@imx93evk:~# jailhouse disable [ 595.150529] CPU: 1 PID: 582 Comm: jailhouse Tainted: G O 6.5.0-rc4-next-20230804-05021-g3d4cc14b42ef-dirty #355 [ 595.161998] Hardware name: NXP i.MX93 11X11 EVK board (DT) [ 595.167475] Call trace: [ 595.169908] dump_backtrace+0x94/0xec [ 595.173573] show_stack+0x18/0x24 [ 595.176884] dump_stack_lvl+0x48/0x60 [ 595.180541] dump_stack+0x18/0x24 [ 595.183843] pci_bus_release_domain_nr+0x34/0x84 [ 595.188453] pci_remove_root_bus+0xa0/0xa4 [ 595.192544] pci_host_common_remove+0x28/0x40 [ 595.196895] platform_remove+0x54/0x6c [ 595.200641] device_remove+0x4c/0x80 [ 595.204209] device_release_driver_internal+0x1d4/0x230 [ 595.209430] device_release_driver+0x18/0x24 [ 595.213691] bus_remove_device+0xcc/0x10c [ 595.217686] device_del+0x15c/0x41c [ 595.221170] platform_device_del.part.0+0x1c/0x88 [ 595.225861] platform_device_unregister+0x24/0x40 [ 595.230557] of_platform_device_destroy+0xfc/0x10c [ 595.235344] of_platform_notify+0x13c/0x178 [ 595.239518] blocking_notifier_call_chain+0x6c/0xa0 [ 595.244389] __of_changeset_entry_notify+0x148/0x16c [ 595.249346] of_changeset_revert+0xa8/0xcc [ 595.253437] jailhouse_pci_virtual_root_devices_remove+0x50/0x74 [jailhouse] [ 595.260484] jailhouse_cmd_disable+0x70/0x1ac [jailhouse] [ 595.265883] jailhouse_ioctl+0x60/0xf0 [jailhouse] [ 595.270674] __arm64_sys_ioctl+0xac/0xf0 [ 595.274595] invoke_syscall+0x48/0x114 [ 595.278336] el0_svc_common.constprop.0+0xc4/0xe4 > > The current ordering is this, where A happens before B: > > A overlay is removed > B pci_host_common_remove > pci_bus_release_domain_nr > of_pci_bus_release_domain_nr > of_get_pci_domain_nr # fails because overlay is gone > ida_free(&pci_domain_nr_dynamic_ida) > > But if the host bridge were removed first, the ordering would be as follows, > and the problem would not occur: > > B pci_host_common_remove > pci_bus_release_domain_nr > of_pci_bus_release_domain_nr > of_get_pci_domain_nr # succeeds in this order > ida_free(&pci_domain_nr_static_ida) > A overlay is removed > > Is there a reason the overlay should be removed before the host bridge? > > Obviously the overlay is loaded before the host bridge is created, and > symmetry would suggest that the overlay should be removed after the host > bridge is removed. Hmm, I need check more. But do you think this patch is fix a real issue or If order is did as you say above, this patch is not required anymore? Thanks, Peng. > > > > bridge) is removed. I would expect the device to be removed before > > > the description of the device is removed. > > > > > > > Then of_pci_bus_release_domain_nr will actually use the dynamic > > > > IDA, even if the IDA was allocated in static IDA. > > > > > > > > Introduce a static_nr field in pci_bus to indicate whether the IDA > > > > is a dynamic or static in order to free the correct one. > > > > > > > > Fixes: c14f7ccc9f5d ("PCI: Assign PCI domain IDs by ida_alloc()") > > > > Signed-off-by: Peng Fan <peng.fan@xxxxxxx> > > > > --- > > > > > > > > V2: > > > > Update commit message > > > > Move static_nr:1 to stay besides others :1 fields. > > > > > > > > drivers/pci/pci.c | 22 ++++++++++++++-------- > > > > include/linux/pci.h | 1 + > > > > 2 files changed, 15 insertions(+), 8 deletions(-) > > > > > > > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index > > > > 60230da957e0..5c98502bcda6 100644 > > > > --- a/drivers/pci/pci.c > > > > +++ b/drivers/pci/pci.c > > > > @@ -6881,10 +6881,10 @@ static void > > > of_pci_reserve_static_domain_nr(void) > > > > } > > > > } > > > > > > > > -static int of_pci_bus_find_domain_nr(struct device *parent) > > > > +static int of_pci_bus_find_domain_nr(struct pci_bus *bus, struct > > > > +device *parent) > > > > { > > > > static bool static_domains_reserved = false; > > > > - int domain_nr; > > > > + int domain_nr, ret; > > > > > > > > /* On the first call scan device tree for static allocations. */ > > > > if (!static_domains_reserved) { > > > > @@ -6892,6 +6892,8 @@ static int of_pci_bus_find_domain_nr(struct > > > device *parent) > > > > static_domains_reserved = true; > > > > } > > > > > > > > + bus->static_nr = 0; > > > > + > > > > if (parent) { > > > > /* > > > > * If domain is in DT, allocate it in static IDA. This @@ - > > > 6899,10 > > > > +6901,14 @@ static int of_pci_bus_find_domain_nr(struct device > > > > +*parent) > > > > * in DT. > > > > */ > > > > domain_nr = of_get_pci_domain_nr(parent->of_node); > > > > - if (domain_nr >= 0) > > > > - return ida_alloc_range(&pci_domain_nr_static_ida, > > > > - domain_nr, domain_nr, > > > > - GFP_KERNEL); > > > > + if (domain_nr >= 0) { > > > > + ret = ida_alloc_range(&pci_domain_nr_static_ida, > > > > + domain_nr, domain_nr, > > > GFP_KERNEL); > > > > + if (ret >= 0) > > > > + bus->static_nr = 1; > > > > + > > > > + return ret; > > > > + } > > > > } > > > > > > > > /* > > > > @@ -6920,7 +6926,7 @@ static void > > > > of_pci_bus_release_domain_nr(struct > > > pci_bus *bus, struct device *par > > > > return; > > > > > > > > /* Release domain from IDA where it was allocated. */ > > > > - if (of_get_pci_domain_nr(parent->of_node) == bus->domain_nr) > > > > + if (bus->static_nr) > > > > ida_free(&pci_domain_nr_static_ida, bus->domain_nr); > > > > else > > > > ida_free(&pci_domain_nr_dynamic_ida, bus->domain_nr); > > > @@ -6928,7 > > > > +6934,7 @@ static void of_pci_bus_release_domain_nr(struct pci_bus > > > > *bus, struct device *par > > > > > > > > int pci_bus_find_domain_nr(struct pci_bus *bus, struct device > > > > *parent) { > > > > - return acpi_disabled ? of_pci_bus_find_domain_nr(parent) : > > > > + return acpi_disabled ? of_pci_bus_find_domain_nr(bus, parent) : > > > > acpi_pci_bus_find_domain_nr(bus); } > > > > > > > > diff --git a/include/linux/pci.h b/include/linux/pci.h index > > > > eeb2e6f6130f..222a1729ea7e 100644 > > > > --- a/include/linux/pci.h > > > > +++ b/include/linux/pci.h > > > > @@ -677,6 +677,7 @@ struct pci_bus { > > > > struct bin_attribute *legacy_mem; /* Legacy mem */ > > > > unsigned int is_added:1; > > > > unsigned int unsafe_warn:1; /* warned about RW1C > > > config write */ > > > > + unsigned int static_nr:1; > > > > }; > > > > > > > > #define to_pci_bus(n) container_of(n, struct pci_bus, dev) > > > > -- > > > > 2.37.1 > > > >
