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Date: Mon, 20 Mar 2023 20:26:05 +0000
From: Jon Hunter <jonathanh@...dia.com>
To: Pali Rohár <pali@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Rob Herring <robh+dt@...nel.org>, Andrew Lunn <andrew@...n.ch>,
Marek Behún <marek.behun@....cz>
Cc: linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v2] PCI: Assign PCI domain by ida_alloc()
Hi Pali,
On 14/07/2022 19:41, Pali Rohár wrote:
> Replace assignment of PCI domain from atomic_inc_return() to ida_alloc().
>
> Use two IDAs, one for static domain allocations (those which are defined in
> device tree) and second for dynamic allocations (all other).
>
> During removal of root bus / host bridge release also allocated domain id.
> So released id can be reused again, for example in situation when
> dynamically loading and unloading native PCI host bridge drivers.
>
> This change also allows to mix static device tree assignment and dynamic by
> kernel as all static allocations are reserved in dynamic pool.
>
> Signed-off-by: Pali Rohár <pali@...nel.org>
> ---
> Idea of this patch comes from the following discussion:
> https://lore.kernel.org/linux-pci/20210412123936.25555-1-pali@kernel.org/t/#u
>
> Changes in v2:
> * Fix broken compilation
> ---
> drivers/pci/pci.c | 103 +++++++++++++++++++++++++------------------
> drivers/pci/probe.c | 5 +++
> drivers/pci/remove.c | 6 +++
> include/linux/pci.h | 1 +
> 4 files changed, 72 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index cfaf40a540a8..34fdcee6634a 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -6762,60 +6762,70 @@ static void pci_no_domains(void)
> }
>
> #ifdef CONFIG_PCI_DOMAINS_GENERIC
> -static atomic_t __domain_nr = ATOMIC_INIT(-1);
> +static DEFINE_IDA(pci_domain_nr_static_ida);
> +static DEFINE_IDA(pci_domain_nr_dynamic_ida);
>
> -static int pci_get_new_domain_nr(void)
> +static void of_pci_reserve_static_domain_nr(void)
> {
> - return atomic_inc_return(&__domain_nr);
> + struct device_node *np;
> + int domain_nr;
> +
> + for_each_node_by_type(np, "pci") {
> + domain_nr = of_get_pci_domain_nr(np);
> + if (domain_nr < 0)
> + continue;
> + /*
> + * Permanently allocate domain_nr in dynamic_ida
> + * to prevent it from dynamic allocation.
> + */
> + ida_alloc_range(&pci_domain_nr_dynamic_ida,
> + domain_nr, domain_nr, GFP_KERNEL);
> + }
> }
>
> static int of_pci_bus_find_domain_nr(struct device *parent)
> {
> - static int use_dt_domains = -1;
> - int domain = -1;
> + static bool static_domains_reserved = false;
> + int domain_nr;
>
> - if (parent)
> - domain = of_get_pci_domain_nr(parent->of_node);
> + /* On the first call scan device tree for static allocations. */
> + if (!static_domains_reserved) {
> + of_pci_reserve_static_domain_nr();
> + static_domains_reserved = true;
> + }
> +
> + if (parent) {
> + /*
> + * If domain is in DT then allocate it in static IDA.
> + * This prevent duplicate static allocations in case
> + * of errors 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);
> + }
>
> /*
> - * Check DT domain and use_dt_domains values.
> - *
> - * If DT domain property is valid (domain >= 0) and
> - * use_dt_domains != 0, the DT assignment is valid since this means
> - * we have not previously allocated a domain number by using
> - * pci_get_new_domain_nr(); we should also update use_dt_domains to
> - * 1, to indicate that we have just assigned a domain number from
> - * DT.
> - *
> - * If DT domain property value is not valid (ie domain < 0), and we
> - * have not previously assigned a domain number from DT
> - * (use_dt_domains != 1) we should assign a domain number by
> - * using the:
> - *
> - * pci_get_new_domain_nr()
> - *
> - * API and update the use_dt_domains value to keep track of method we
> - * are using to assign domain numbers (use_dt_domains = 0).
> - *
> - * All other combinations imply we have a platform that is trying
> - * to mix domain numbers obtained from DT and pci_get_new_domain_nr(),
> - * which is a recipe for domain mishandling and it is prevented by
> - * invalidating the domain value (domain = -1) and printing a
> - * corresponding error.
> + * If domain was not specified in DT then choose free id from dynamic
> + * allocations. All domain numbers from DT are permanently in dynamic
> + * allocations to prevent assigning them to other DT nodes without
> + * static domain.
> */
> - if (domain >= 0 && use_dt_domains) {
> - use_dt_domains = 1;
> - } else if (domain < 0 && use_dt_domains != 1) {
> - use_dt_domains = 0;
> - domain = pci_get_new_domain_nr();
> - } else {
> - if (parent)
> - pr_err("Node %pOF has ", parent->of_node);
> - pr_err("Inconsistent \"linux,pci-domain\" property in DT\n");
> - domain = -1;
> - }
> + return ida_alloc(&pci_domain_nr_dynamic_ida, GFP_KERNEL);
> +}
>
> - return domain;
> +static void of_pci_bus_release_domain_nr(struct pci_bus *bus, struct device *parent)
> +{
> + if (bus->domain_nr < 0)
> + return;
> +
> + /* Release domain from ida in which was it allocated. */
> + if (of_get_pci_domain_nr(parent->of_node) == bus->domain_nr)
> + ida_free(&pci_domain_nr_static_ida, bus->domain_nr);
> + else
> + ida_free(&pci_domain_nr_dynamic_ida, bus->domain_nr);
> }
>
> int pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent)
> @@ -6823,6 +6833,13 @@ int pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent)
> return acpi_disabled ? of_pci_bus_find_domain_nr(parent) :
> acpi_pci_bus_find_domain_nr(bus);
> }
> +
> +void pci_bus_release_domain_nr(struct pci_bus *bus, struct device *parent)
> +{
> + if (!acpi_disabled)
> + return;
> + of_pci_bus_release_domain_nr(bus, parent);
> +}
> #endif
>
> /**
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 17a969942d37..12092d238403 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -906,6 +906,8 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
> bus->domain_nr = pci_bus_find_domain_nr(bus, parent);
> else
> bus->domain_nr = bridge->domain_nr;
> + if (bus->domain_nr < 0)
> + goto free;
> #endif
>
> b = pci_find_bus(pci_domain_nr(bus), bridge->busnr);
> @@ -1030,6 +1032,9 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
> device_del(&bridge->dev);
>
> free:
> +#ifdef CONFIG_PCI_DOMAINS_GENERIC
> + pci_bus_release_domain_nr(bus, parent);
> +#endif
> kfree(bus);
> return err;
> }
> diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
> index 4c54c75050dc..0145aef1b930 100644
> --- a/drivers/pci/remove.c
> +++ b/drivers/pci/remove.c
> @@ -160,6 +160,12 @@ void pci_remove_root_bus(struct pci_bus *bus)
> pci_remove_bus(bus);
> host_bridge->bus = NULL;
>
> +#ifdef CONFIG_PCI_DOMAINS_GENERIC
> + /* Release domain_nr if it was dynamically allocated */
> + if (host_bridge->domain_nr == PCI_DOMAIN_NR_NOT_SET)
> + pci_bus_release_domain_nr(bus, host_bridge->dev.parent);
> +#endif
> +
> /* remove the host bridge */
> device_del(&host_bridge->dev);
> }
After this change was made we are seeing the following bug
report on a Tegra234 Jetson Orin board ...
[ 17.172346] tegra194-pcie 141a0000.pcie: host bridge /pcie@...a0000 ranges:
[ 17.172470] tegra194-pcie 141a0000.pcie: MEM 0x2800000000..0x2b27ffffff -> 0x2800000000
[ 17.172519] tegra194-pcie 141a0000.pcie: MEM 0x2b28000000..0x2b2fffffff -> 0x0040000000
[ 17.172548] tegra194-pcie 141a0000.pcie: IO 0x003a100000..0x003a1fffff -> 0x003a100000
[ 17.173449] tegra194-pcie 141a0000.pcie: iATU: unroll T, 8 ob, 2 ib, align 64K, limit 32G
[ 18.279048] tegra194-pcie 141a0000.pcie: Phy link never came up
[ 19.279285] tegra194-pcie 141a0000.pcie: Phy link never came up
[ 19.279599] tegra194-pcie 141a0000.pcie: PCI host bridge to bus 0005:00
[ 19.279613] pci_bus 0005:00: root bus resource [bus 00-ff]
[ 19.279622] pci_bus 0005:00: root bus resource [mem 0x2800000000-0x2b27ffffff pref]
[ 19.279631] pci_bus 0005:00: root bus resource [mem 0x2b28000000-0x2b2fffffff] (bus address [0x40000000-0x47ffffff])
[ 19.279639] pci_bus 0005:00: root bus resource [io 0x200000-0x2fffff] (bus address [0x3a100000-0x3a1fffff])
[ 19.279687] pci 0005:00:00.0: [10de:229a] type 01 class 0x060400
[ 19.279886] pci 0005:00:00.0: PME# supported from D0 D3hot
[ 19.283256] pci 0005:00:00.0: PCI bridge to [bus 01-ff]
[ 19.283590] pcieport 0005:00:00.0: Adding to iommu group 26
[ 19.283991] pcieport 0005:00:00.0: PME: Signaling with IRQ 174
[ 19.284429] pcieport 0005:00:00.0: AER: enabled with IRQ 174
[ 19.285003] pci_bus 0005:01: busn_res: [bus 01-ff] is released
[ 19.285591] pci 0005:00:00.0: Removing from iommu group 26
[ 19.285751] pci_bus 0005:00: busn_res: [bus 00-ff] is released
[ 19.285870] ==================================================================
[ 19.293351] BUG: KFENCE: use-after-free read in pci_bus_release_domain_nr+0x10/0x70
[ 19.302817] Use-after-free read at 0x000000007f3b80eb (in kfence-#115):
[ 19.309677] pci_bus_release_domain_nr+0x10/0x70
[ 19.309691] dw_pcie_host_deinit+0x28/0x78
[ 19.309702] tegra_pcie_deinit_controller+0x1c/0x38 [pcie_tegra194]
[ 19.309734] tegra_pcie_dw_probe+0x648/0xb28 [pcie_tegra194]
[ 19.309752] platform_probe+0x90/0xd8
[ 19.309764] really_probe+0xb8/0x298
[ 19.309777] __driver_probe_device+0x78/0xd8
[ 19.309788] driver_probe_device+0x38/0x120
[ 19.309799] __device_attach_driver+0x94/0xe0
[ 19.309812] bus_for_each_drv+0x70/0xc8
[ 19.309822] __device_attach+0xfc/0x188
[ 19.309833] device_initial_probe+0x10/0x18
[ 19.309844] bus_probe_device+0x94/0xa0
[ 19.309854] deferred_probe_work_func+0x80/0xb8
[ 19.309864] process_one_work+0x1e0/0x348
[ 19.309882] worker_thread+0x48/0x410
[ 19.309891] kthread+0xf4/0x110
[ 19.309904] ret_from_fork+0x10/0x20
[ 19.311457] kfence-#115: 0x00000000063a155a-0x00000000ba698da8, size=1072, cache=kmalloc-2k
[ 19.311469] allocated by task 96 on cpu 10 at 19.279323s:
[ 19.311562] __kmem_cache_alloc_node+0x260/0x278
[ 19.311571] kmalloc_trace+0x24/0x30
[ 19.311580] pci_alloc_bus+0x24/0xa0
[ 19.311590] pci_register_host_bridge+0x48/0x4b8
[ 19.311601] pci_scan_root_bus_bridge+0xc0/0xe8
[ 19.311613] pci_host_probe+0x18/0xc0
[ 19.311623] dw_pcie_host_init+0x2c0/0x568
[ 19.311630] tegra_pcie_dw_probe+0x610/0xb28 [pcie_tegra194]
[ 19.311647] platform_probe+0x90/0xd8
[ 19.311653] really_probe+0xb8/0x298
[ 19.311663] __driver_probe_device+0x78/0xd8
[ 19.311672] driver_probe_device+0x38/0x120
[ 19.311682] __device_attach_driver+0x94/0xe0
[ 19.311694] bus_for_each_drv+0x70/0xc8
[ 19.311702] __device_attach+0xfc/0x188
[ 19.311713] device_initial_probe+0x10/0x18
[ 19.311724] bus_probe_device+0x94/0xa0
[ 19.311733] deferred_probe_work_func+0x80/0xb8
[ 19.311743] process_one_work+0x1e0/0x348
[ 19.311753] worker_thread+0x48/0x410
[ 19.311763] kthread+0xf4/0x110
[ 19.311771] ret_from_fork+0x10/0x20
[ 19.311782] freed by task 96 on cpu 10 at 19.285833s:
[ 19.311799] release_pcibus_dev+0x30/0x40
[ 19.311808] device_release+0x30/0x90
[ 19.311814] kobject_put+0xa8/0x120
[ 19.311832] device_unregister+0x20/0x30
[ 19.311839] pci_remove_bus+0x78/0x88
[ 19.311850] pci_remove_root_bus+0x5c/0x98
[ 19.311860] dw_pcie_host_deinit+0x28/0x78
[ 19.311866] tegra_pcie_deinit_controller+0x1c/0x38 [pcie_tegra194]
[ 19.311883] tegra_pcie_dw_probe+0x648/0xb28 [pcie_tegra194]
[ 19.311900] platform_probe+0x90/0xd8
[ 19.311906] really_probe+0xb8/0x298
[ 19.311916] __driver_probe_device+0x78/0xd8
[ 19.311926] driver_probe_device+0x38/0x120
[ 19.311936] __device_attach_driver+0x94/0xe0
[ 19.311947] bus_for_each_drv+0x70/0xc8
[ 19.311956] __device_attach+0xfc/0x188
[ 19.311966] device_initial_probe+0x10/0x18
[ 19.311976] bus_probe_device+0x94/0xa0
[ 19.311985] deferred_probe_work_func+0x80/0xb8
[ 19.311995] process_one_work+0x1e0/0x348
[ 19.312005] worker_thread+0x48/0x410
[ 19.312014] kthread+0xf4/0x110
[ 19.312022] ret_from_fork+0x10/0x20
[ 19.313579] CPU: 10 PID: 96 Comm: kworker/u24:2 Not tainted 6.2.0 #4
[ 19.320171] Hardware name: /, BIOS 1.0-d7fb19b 08/10/2022
[ 19.325852] Workqueue: events_unbound deferred_probe_work_func
[ 19.331919] ==================================================================
After reverting this change I no longer see this issue.
Let me know if you have any thoughts.
Thanks
Jon
--
nvpublic
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