From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- drivers/iommu/irq_remapping.c | 167 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 167 insertions(+) create mode 100644 drivers/iommu/irq_remapping.c (limited to 'drivers/iommu/irq_remapping.c') diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c new file mode 100644 index 000000000..41bf65e4e --- /dev/null +++ b/drivers/iommu/irq_remapping.c @@ -0,0 +1,167 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include + +#include "irq_remapping.h" + +int irq_remapping_enabled; +int irq_remap_broken; +int disable_sourceid_checking; +int no_x2apic_optout; + +int disable_irq_post = 0; + +bool enable_posted_msi __ro_after_init; + +static int disable_irq_remap; +static struct irq_remap_ops *remap_ops; + +static void irq_remapping_restore_boot_irq_mode(void) +{ + /* + * With interrupt-remapping, for now we will use virtual wire A + * mode, as virtual wire B is little complex (need to configure + * both IOAPIC RTE as well as interrupt-remapping table entry). + * As this gets called during crash dump, keep this simple for + * now. + */ + if (boot_cpu_has(X86_FEATURE_APIC) || apic_from_smp_config()) + disconnect_bsp_APIC(0); +} + +static void __init irq_remapping_modify_x86_ops(void) +{ + x86_apic_ops.restore = irq_remapping_restore_boot_irq_mode; +} + +static __init int setup_nointremap(char *str) +{ + disable_irq_remap = 1; + return 0; +} +early_param("nointremap", setup_nointremap); + +static __init int setup_irqremap(char *str) +{ + if (!str) + return -EINVAL; + + while (*str) { + if (!strncmp(str, "on", 2)) { + disable_irq_remap = 0; + disable_irq_post = 0; + } else if (!strncmp(str, "off", 3)) { + disable_irq_remap = 1; + disable_irq_post = 1; + } else if (!strncmp(str, "nosid", 5)) + disable_sourceid_checking = 1; + else if (!strncmp(str, "no_x2apic_optout", 16)) + no_x2apic_optout = 1; + else if (!strncmp(str, "nopost", 6)) + disable_irq_post = 1; + else if (IS_ENABLED(CONFIG_X86_POSTED_MSI) && !strncmp(str, "posted_msi", 10)) + enable_posted_msi = true; + str += strcspn(str, ","); + while (*str == ',') + str++; + } + + return 0; +} +early_param("intremap", setup_irqremap); + +void set_irq_remapping_broken(void) +{ + irq_remap_broken = 1; +} + +bool irq_remapping_cap(enum irq_remap_cap cap) +{ + if (!remap_ops || disable_irq_post) + return false; + + return (remap_ops->capability & (1 << cap)); +} +EXPORT_SYMBOL_GPL(irq_remapping_cap); + +int __init irq_remapping_prepare(void) +{ + if (disable_irq_remap) + return -ENOSYS; + + if (IS_ENABLED(CONFIG_INTEL_IOMMU) && + intel_irq_remap_ops.prepare() == 0) + remap_ops = &intel_irq_remap_ops; + else if (IS_ENABLED(CONFIG_AMD_IOMMU) && + amd_iommu_irq_ops.prepare() == 0) + remap_ops = &amd_iommu_irq_ops; + else if (IS_ENABLED(CONFIG_HYPERV) && + hyperv_irq_remap_ops.prepare() == 0) + remap_ops = &hyperv_irq_remap_ops; + else + return -ENOSYS; + + return 0; +} + +int __init irq_remapping_enable(void) +{ + int ret; + + if (!remap_ops->enable) + return -ENODEV; + + ret = remap_ops->enable(); + + if (irq_remapping_enabled) + irq_remapping_modify_x86_ops(); + + return ret; +} + +void irq_remapping_disable(void) +{ + if (irq_remapping_enabled && remap_ops->disable) + remap_ops->disable(); +} + +int irq_remapping_reenable(int mode) +{ + if (irq_remapping_enabled && remap_ops->reenable) + return remap_ops->reenable(mode); + + return 0; +} + +int __init irq_remap_enable_fault_handling(void) +{ + if (!irq_remapping_enabled) + return 0; + + if (!remap_ops->enable_faulting) + return -ENODEV; + + cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "dmar:enable_fault_handling", + remap_ops->enable_faulting, NULL); + + return remap_ops->enable_faulting(smp_processor_id()); +} + +void panic_if_irq_remap(const char *msg) +{ + if (irq_remapping_enabled) + panic(msg); +} -- cgit v1.3.1