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, 115 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/booke.h b/arch/powerpc/kvm/booke.h
new file mode 100644
index 000000000..9c5b8e760
--- /dev/null
+++ b/arch/powerpc/kvm/booke.h
@@ -0,0 +1,115 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ *
+ * Copyright IBM Corp. 2008
+ *
+ * Authors: Hollis Blanchard <hollisb@us.ibm.com>
+ */
+
+#ifndef __KVM_BOOKE_H__
+#define __KVM_BOOKE_H__
+
+#include <linux/types.h>
+#include <linux/kvm_host.h>
+#include <asm/kvm_ppc.h>
+#include <asm/switch_to.h>
+#include "timing.h"
+
+/* interrupt priortity ordering */
+#define BOOKE_IRQPRIO_DATA_STORAGE 0
+#define BOOKE_IRQPRIO_INST_STORAGE 1
+#define BOOKE_IRQPRIO_ALIGNMENT 2
+#define BOOKE_IRQPRIO_PROGRAM 3
+#define BOOKE_IRQPRIO_FP_UNAVAIL 4
+#ifdef CONFIG_SPE_POSSIBLE
+#define BOOKE_IRQPRIO_SPE_UNAVAIL 5
+#define BOOKE_IRQPRIO_SPE_FP_DATA 6
+#define BOOKE_IRQPRIO_SPE_FP_ROUND 7
+#endif
+#ifdef CONFIG_PPC_E500MC
+#define BOOKE_IRQPRIO_ALTIVEC_UNAVAIL 5
+#define BOOKE_IRQPRIO_ALTIVEC_ASSIST 6
+#endif
+#define BOOKE_IRQPRIO_SYSCALL 8
+#define BOOKE_IRQPRIO_AP_UNAVAIL 9
+#define BOOKE_IRQPRIO_DTLB_MISS 10
+#define BOOKE_IRQPRIO_ITLB_MISS 11
+#define BOOKE_IRQPRIO_MACHINE_CHECK 12
+#define BOOKE_IRQPRIO_DEBUG 13
+#define BOOKE_IRQPRIO_CRITICAL 14
+#define BOOKE_IRQPRIO_WATCHDOG 15
+#define BOOKE_IRQPRIO_EXTERNAL 16
+#define BOOKE_IRQPRIO_FIT 17
+#define BOOKE_IRQPRIO_DECREMENTER 18
+#define BOOKE_IRQPRIO_PERFORMANCE_MONITOR 19
+/* Internal pseudo-irqprio for level triggered externals */
+#define BOOKE_IRQPRIO_EXTERNAL_LEVEL 20
+#define BOOKE_IRQPRIO_DBELL 21
+#define BOOKE_IRQPRIO_DBELL_CRIT 22
+#define BOOKE_IRQPRIO_MAX 23
+
+#define BOOKE_IRQMASK_EE ((1 << BOOKE_IRQPRIO_EXTERNAL_LEVEL) | \
+			  (1 << BOOKE_IRQPRIO_PERFORMANCE_MONITOR) | \
+			  (1 << BOOKE_IRQPRIO_DBELL) | \
+			  (1 << BOOKE_IRQPRIO_DECREMENTER) | \
+			  (1 << BOOKE_IRQPRIO_FIT) | \
+			  (1 << BOOKE_IRQPRIO_EXTERNAL))
+
+#define BOOKE_IRQMASK_CE ((1 << BOOKE_IRQPRIO_DBELL_CRIT) | \
+			  (1 << BOOKE_IRQPRIO_WATCHDOG) | \
+			  (1 << BOOKE_IRQPRIO_CRITICAL))
+
+extern unsigned long kvmppc_booke_handlers;
+extern unsigned long kvmppc_booke_handler_addr[];
+
+void kvmppc_set_msr(struct kvm_vcpu *vcpu, u32 new_msr);
+void kvmppc_mmu_msr_notify(struct kvm_vcpu *vcpu, u32 old_msr);
+
+void kvmppc_set_epcr(struct kvm_vcpu *vcpu, u32 new_epcr);
+void kvmppc_set_tcr(struct kvm_vcpu *vcpu, u32 new_tcr);
+void kvmppc_set_tsr_bits(struct kvm_vcpu *vcpu, u32 tsr_bits);
+void kvmppc_clr_tsr_bits(struct kvm_vcpu *vcpu, u32 tsr_bits);
+
+int kvmppc_booke_emulate_op(struct kvm_vcpu *vcpu,
+                            unsigned int inst, int *advance);
+int kvmppc_booke_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val);
+int kvmppc_booke_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val);
+
+/* low-level asm code to transfer guest state */
+void kvmppc_load_guest_spe(struct kvm_vcpu *vcpu);
+void kvmppc_save_guest_spe(struct kvm_vcpu *vcpu);
+
+/* high-level function, manages flags, host state */
+void kvmppc_vcpu_disable_spe(struct kvm_vcpu *vcpu);
+
+void kvmppc_booke_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
+void kvmppc_booke_vcpu_put(struct kvm_vcpu *vcpu);
+
+enum int_class {
+	INT_CLASS_NONCRIT,
+	INT_CLASS_CRIT,
+	INT_CLASS_MC,
+	INT_CLASS_DBG,
+};
+
+void kvmppc_set_pending_interrupt(struct kvm_vcpu *vcpu, enum int_class type);
+
+extern int kvmppc_core_emulate_op_e500(struct kvm_vcpu *vcpu,
+				       unsigned int inst, int *advance);
+extern int kvmppc_core_emulate_mtspr_e500(struct kvm_vcpu *vcpu, int sprn,
+					  ulong spr_val);
+extern int kvmppc_core_emulate_mfspr_e500(struct kvm_vcpu *vcpu, int sprn,
+					  ulong *spr_val);
+extern int kvmppc_core_emulate_mtspr_e500(struct kvm_vcpu *vcpu, int sprn,
+					  ulong spr_val);
+extern int kvmppc_core_emulate_mfspr_e500(struct kvm_vcpu *vcpu, int sprn,
+					  ulong *spr_val);
+
+static inline void kvmppc_clear_dbsr(void)
+{
+	mtspr(SPRN_DBSR, mfspr(SPRN_DBSR));
+}
+
+int kvmppc_handle_exit(struct kvm_vcpu *vcpu, unsigned int exit_nr);
+
+#endif /* __KVM_BOOKE_H__ */