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, 105 insertions, 0 deletions

diff --git a/drivers/iommu/amd/quirks.c b/drivers/iommu/amd/quirks.c
new file mode 100644
index 000000000..79dbb8f33
--- /dev/null
+++ b/drivers/iommu/amd/quirks.c
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/*
+ * Quirks for AMD IOMMU
+ *
+ * Copyright (C) 2019 Kai-Heng Feng <kai.heng.feng@canonical.com>
+ */
+
+#ifdef CONFIG_DMI
+#include <linux/dmi.h>
+
+#include "amd_iommu.h"
+
+#define IVHD_SPECIAL_IOAPIC		1
+
+struct ivrs_quirk_entry {
+	u8 id;
+	u32 devid;
+};
+
+enum {
+	DELL_INSPIRON_7375 = 0,
+	DELL_LATITUDE_5495,
+	LENOVO_IDEAPAD_330S_15ARR,
+};
+
+static const struct ivrs_quirk_entry ivrs_ioapic_quirks[][3] __initconst = {
+	/* ivrs_ioapic[4]=00:14.0 ivrs_ioapic[5]=00:00.2 */
+	[DELL_INSPIRON_7375] = {
+		{ .id = 4, .devid = 0xa0 },
+		{ .id = 5, .devid = 0x2 },
+		{}
+	},
+	/* ivrs_ioapic[4]=00:14.0 */
+	[DELL_LATITUDE_5495] = {
+		{ .id = 4, .devid = 0xa0 },
+		{}
+	},
+	/* ivrs_ioapic[32]=00:14.0 */
+	[LENOVO_IDEAPAD_330S_15ARR] = {
+		{ .id = 32, .devid = 0xa0 },
+		{}
+	},
+	{}
+};
+
+static int __init ivrs_ioapic_quirk_cb(const struct dmi_system_id *d)
+{
+	const struct ivrs_quirk_entry *i;
+
+	for (i = d->driver_data; i->id != 0 && i->devid != 0; i++)
+		add_special_device(IVHD_SPECIAL_IOAPIC, i->id, (u32 *)&i->devid, 0);
+
+	return 0;
+}
+
+static const struct dmi_system_id ivrs_quirks[] __initconst = {
+	{
+		.callback = ivrs_ioapic_quirk_cb,
+		.ident = "Dell Inspiron 7375",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron 7375"),
+		},
+		.driver_data = (void *)&ivrs_ioapic_quirks[DELL_INSPIRON_7375],
+	},
+	{
+		.callback = ivrs_ioapic_quirk_cb,
+		.ident = "Dell Latitude 5495",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Latitude 5495"),
+		},
+		.driver_data = (void *)&ivrs_ioapic_quirks[DELL_LATITUDE_5495],
+	},
+	{
+		/*
+		 * Acer Aspire A315-41 requires the very same workaround as
+		 * Dell Latitude 5495
+		 */
+		.callback = ivrs_ioapic_quirk_cb,
+		.ident = "Acer Aspire A315-41",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Aspire A315-41"),
+		},
+		.driver_data = (void *)&ivrs_ioapic_quirks[DELL_LATITUDE_5495],
+	},
+	{
+		.callback = ivrs_ioapic_quirk_cb,
+		.ident = "Lenovo ideapad 330S-15ARR",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "81FB"),
+		},
+		.driver_data = (void *)&ivrs_ioapic_quirks[LENOVO_IDEAPAD_330S_15ARR],
+	},
+	{}
+};
+
+void __init amd_iommu_apply_ivrs_quirks(void)
+{
+	dmi_check_system(ivrs_quirks);
+}
+#endif