selftests/bpf: Reject graph kptr use after RCU unlockgrafted

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 <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 255 insertions, 0 deletions

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
new file mode 100644
index 000000000..ce5bc0d9e
--- /dev/null
+++ b/drivers/virtio/Kconfig
@@ -0,0 +1,255 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config VIRTIO_ANCHOR
+	bool
+
+config VIRTIO
+	tristate
+	select VIRTIO_ANCHOR
+	help
+	  This option is selected by any driver which implements the virtio
+	  bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_RPMSG
+	  or CONFIG_S390_GUEST.
+
+config VIRTIO_PCI_LIB
+	tristate
+	help
+	  Modern PCI device implementation. This module implements the
+	  basic probe and control for devices which are based on modern
+	  PCI device with possible vendor specific extensions. Any
+	  module that selects this module must depend on PCI.
+
+config VIRTIO_PCI_LIB_LEGACY
+	tristate
+	help
+	  Legacy PCI device (Virtio PCI Card 0.9.x Draft and older device)
+	  implementation.
+	  This module implements the basic probe and control for devices
+	  which are based on legacy PCI device. Any module that selects this
+	  module must depend on PCI.
+
+menuconfig VIRTIO_MENU
+	bool "Virtio drivers"
+	default y
+
+if VIRTIO_MENU
+
+config VIRTIO_HARDEN_NOTIFICATION
+        bool "Harden virtio notification"
+        depends on BROKEN
+        help
+          Enable this to harden the device notifications and suppress
+          those that happen at a time where notifications are illegal.
+
+          Experimental: Note that several drivers still have issues that
+          may cause crashes or hangs when correct handling of
+          notifications is enforced; depending on the subset of
+          drivers and devices you use, this may or may not work.
+
+          If unsure, say N.
+
+config VIRTIO_PCI
+	tristate "PCI driver for virtio devices"
+	depends on PCI
+	select VIRTIO_PCI_LIB
+	select VIRTIO
+	help
+	  This driver provides support for virtio based paravirtual device
+	  drivers over PCI.  This requires that your VMM has appropriate PCI
+	  virtio backends.  Most QEMU based VMMs should support these devices
+	  (like KVM or Xen).
+
+	  If unsure, say M.
+
+config VIRTIO_PCI_ADMIN_LEGACY
+	bool
+	depends on VIRTIO_PCI && (X86 || COMPILE_TEST)
+	default y
+
+config VIRTIO_PCI_LEGACY
+	bool "Support for legacy virtio draft 0.9.X and older devices"
+	default y
+	depends on VIRTIO_PCI
+	select VIRTIO_PCI_LIB_LEGACY
+	help
+          Virtio PCI Card 0.9.X Draft (circa 2014) and older device support.
+
+	  This option enables building a transitional driver, supporting
+	  both devices conforming to Virtio 1 specification, and legacy devices.
+	  If disabled, you get a slightly smaller, non-transitional driver,
+	  with no legacy compatibility.
+
+          So look out into your driveway.  Do you have a flying car?  If
+          so, you can happily disable this option and virtio will not
+          break.  Otherwise, leave it set.  Unless you're testing what
+          life will be like in The Future.
+
+	  If unsure, say Y.
+
+config VIRTIO_VDPA
+	tristate "vDPA driver for virtio devices"
+	depends on VDPA
+	select VIRTIO
+	help
+	  This driver provides support for virtio based paravirtual
+	  device driver over vDPA bus. For this to be useful, you need
+	  an appropriate vDPA device implementation that operates on a
+	  physical device to allow the datapath of virtio to be
+	  offloaded to hardware.
+
+	  If unsure, say M.
+
+config VIRTIO_PMEM
+	tristate "Support for virtio pmem driver"
+	depends on VIRTIO
+	depends on LIBNVDIMM
+	help
+	  This driver provides access to virtio-pmem devices, storage devices
+	  that are mapped into the physical address space - similar to NVDIMMs
+	   - with a virtio-based flushing interface.
+
+	  If unsure, say Y.
+
+config VIRTIO_BALLOON
+	tristate "Virtio balloon driver"
+	depends on VIRTIO
+	select BALLOON
+	select PAGE_REPORTING
+	help
+	 This driver supports increasing and decreasing the amount
+	 of memory within a KVM guest.
+
+	 If unsure, say M.
+
+config VIRTIO_MEM
+	tristate "Virtio mem driver"
+	depends on X86_64 || ARM64 || RISCV || S390
+	depends on VIRTIO
+	depends on MEMORY_HOTPLUG
+	depends on MEMORY_HOTREMOVE
+	depends on CONTIG_ALLOC
+	depends on EXCLUSIVE_SYSTEM_RAM
+	help
+	 This driver provides access to virtio-mem paravirtualized memory
+	 devices, allowing to hotplug and hotunplug memory.
+
+	 This driver currently supports x86-64, arm64, riscv and s390.
+	 Although it should compile on other architectures that implement
+	 memory hot(un)plug, architecture-specific and/or common
+	 code changes may be required for virtio-mem, kdump and kexec to
+	 work as expected.
+
+	 If unsure, say M.
+
+config VIRTIO_INPUT
+	tristate "Virtio input driver"
+	depends on VIRTIO
+	depends on INPUT
+	help
+	 This driver supports virtio input devices such as
+	 keyboards, mice and tablets.
+
+	 If unsure, say M.
+
+config VIRTIO_MMIO
+	tristate "Platform bus driver for memory mapped virtio devices"
+	depends on HAS_IOMEM && HAS_DMA
+	select VIRTIO
+	help
+	 This drivers provides support for memory mapped virtio
+	 platform device driver.
+
+ 	 If unsure, say N.
+
+config VIRTIO_MMIO_CMDLINE_DEVICES
+	bool "Memory mapped virtio devices parameter parsing"
+	depends on VIRTIO_MMIO
+	help
+	 Allow virtio-mmio devices instantiation via the kernel command line
+	 or module parameters. Be aware that using incorrect parameters (base
+	 address in particular) can crash your system - you have been warned.
+	 See Documentation/admin-guide/kernel-parameters.rst for details.
+
+	 If unsure, say 'N'.
+
+config VIRTIO_DMA_SHARED_BUFFER
+	tristate
+	depends on DMA_SHARED_BUFFER
+	help
+	 This option adds a flavor of dma buffers that are backed by
+	 virtio resources.
+
+config VIRTIO_DEBUG
+	bool "Debug facilities"
+	depends on VIRTIO
+	help
+	  Enable this to expose debug facilities over debugfs.
+	  This allows to debug features, to see what features the device
+	  advertises and to set filter for features used by driver.
+
+	  If unsure, say N.
+
+config VIRTIO_RTC
+	tristate "Virtio RTC driver"
+	depends on VIRTIO
+	depends on PTP_1588_CLOCK_OPTIONAL
+	help
+	 This driver provides current time from a Virtio RTC device. The driver
+	 provides the time through one or more clocks. The Virtio RTC PTP
+	 clocks and/or the Real Time Clock driver for Virtio RTC must be
+	 enabled to expose the clocks to userspace.
+
+	 To compile this code as a module, choose M here: the module will be
+	 called virtio_rtc.
+
+	 If unsure, say M.
+
+if VIRTIO_RTC
+
+comment "WARNING: Consider enabling VIRTIO_RTC_PTP and/or VIRTIO_RTC_CLASS."
+	depends on !VIRTIO_RTC_PTP && !VIRTIO_RTC_CLASS
+
+comment "Enable PTP_1588_CLOCK in order to enable VIRTIO_RTC_PTP."
+	depends on PTP_1588_CLOCK=n
+
+config VIRTIO_RTC_PTP
+	bool "Virtio RTC PTP clocks"
+	default y
+	depends on PTP_1588_CLOCK
+	help
+	 This exposes any Virtio RTC clocks as PTP Hardware Clocks (PHCs) to
+	 userspace. The PHC sysfs attribute "clock_name" describes the clock
+	 type.
+
+	 If unsure, say Y.
+
+config VIRTIO_RTC_ARM
+	bool "Virtio RTC cross-timestamping using Arm Generic Timer"
+	default y
+	depends on VIRTIO_RTC_PTP && ARM_ARCH_TIMER
+	help
+	 This enables Virtio RTC cross-timestamping using the Arm Generic Timer.
+	 It only has an effect if the Virtio RTC device also supports this. The
+	 cross-timestamp is available through the PTP clock driver precise
+	 cross-timestamp ioctl (PTP_SYS_OFFSET_PRECISE2 aka
+	 PTP_SYS_OFFSET_PRECISE).
+
+	 If unsure, say Y.
+
+comment "Enable RTC_CLASS in order to enable VIRTIO_RTC_CLASS."
+	depends on RTC_CLASS=n
+
+config VIRTIO_RTC_CLASS
+	bool "Real Time Clock driver for Virtio RTC"
+	default y
+	depends on RTC_CLASS
+	help
+	 This exposes the Virtio RTC UTC-like clock as a Linux Real Time Clock.
+	 It only has an effect if the Virtio RTC device has a UTC-like clock
+	 which smears leap seconds to avoid steps. The Real Time Clock is
+	 read-only, and may support setting an alarm.
+
+	 If unsure, say Y.
+
+endif # VIRTIO_RTC
+
+endif # VIRTIO_MENU