Add support for implementing bpf pvsched drivers. bpf programs can use
the struct_ops to define the callbacks of pvsched drivers.
This is only a skeleton of the bpf framework for pvsched. Some
verification details are not implemented yet.
Signed-off-by: Vineeth Pillai (Google) <vineeth@xxxxxxxxxxxxxxx>
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
kernel/bpf/bpf_struct_ops_types.h | 4 +
virt/pvsched/Makefile | 2 +-
virt/pvsched/pvsched_bpf.c | 141 ++++++++++++++++++++++++++++++
3 files changed, 146 insertions(+), 1 deletion(-)
create mode 100644 virt/pvsched/pvsched_bpf.c
diff --git a/kernel/bpf/bpf_struct_ops_types.h b/kernel/bpf/bpf_struct_ops_types.h
index 5678a9ddf817..9d5e4d1a331a 100644
--- a/kernel/bpf/bpf_struct_ops_types.h
+++ b/kernel/bpf/bpf_struct_ops_types.h
@@ -9,4 +9,8 @@ BPF_STRUCT_OPS_TYPE(bpf_dummy_ops)
#include <net/tcp.h>
BPF_STRUCT_OPS_TYPE(tcp_congestion_ops)
#endif
+#ifdef CONFIG_PARAVIRT_SCHED_HOST
+#include <linux/pvsched.h>
+BPF_STRUCT_OPS_TYPE(pvsched_vcpu_ops)
+#endif
#endif
diff --git a/virt/pvsched/Makefile b/virt/pvsched/Makefile
index 4ca38e30479b..02bc072cd806 100644
--- a/virt/pvsched/Makefile
+++ b/virt/pvsched/Makefile
@@ -1,2 +1,2 @@
-obj-$(CONFIG_PARAVIRT_SCHED_HOST) += pvsched.o
+obj-$(CONFIG_PARAVIRT_SCHED_HOST) += pvsched.o pvsched_bpf.o
diff --git a/virt/pvsched/pvsched_bpf.c b/virt/pvsched/pvsched_bpf.c
new file mode 100644
index 000000000000..b125089abc3b
--- /dev/null
+++ b/virt/pvsched/pvsched_bpf.c
@@ -0,0 +1,141 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Google */
+
+#include <linux/types.h>
+#include <linux/bpf_verifier.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/filter.h>
+#include <linux/pvsched.h>
+
+
+/* "extern" is to avoid sparse warning. It is only used in bpf_struct_ops.c. */
+extern struct bpf_struct_ops bpf_pvsched_vcpu_ops;
+
+static int bpf_pvsched_vcpu_init(struct btf *btf)
+{
+ return 0;
+}
+
+static bool bpf_pvsched_vcpu_is_valid_access(int off, int size,
+ enum bpf_access_type type,
+ const struct bpf_prog *prog,
+ struct bpf_insn_access_aux *info)
+{
+ if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)
+ return false;
+ if (type != BPF_READ)
+ return false;
+ if (off % size != 0)
+ return false;
+
+ if (!btf_ctx_access(off, size, type, prog, info))
+ return false;
+
+ return true;
+}
+
+static int bpf_pvsched_vcpu_btf_struct_access(struct bpf_verifier_log *log,
+ const struct bpf_reg_state *reg,
+ int off, int size)
+{
+ /*
+ * TODO: Enable write access to Guest shared mem.
+ */
+ return -EACCES;
+}
+
+static const struct bpf_func_proto *
+bpf_pvsched_vcpu_get_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
+{
+ return bpf_base_func_proto(func_id);
+}
+
+static const struct bpf_verifier_ops bpf_pvsched_vcpu_verifier_ops = {
+ .get_func_proto = bpf_pvsched_vcpu_get_func_proto,
+ .is_valid_access = bpf_pvsched_vcpu_is_valid_access,
+ .btf_struct_access = bpf_pvsched_vcpu_btf_struct_access,
+};
+
+static int bpf_pvsched_vcpu_init_member(const struct btf_type *t,
+ const struct btf_member *member,
+ void *kdata, const void *udata)
+{
+ const struct pvsched_vcpu_ops *uvm_ops;
+ struct pvsched_vcpu_ops *vm_ops;
+ u32 moff;
+
+ uvm_ops = (const struct pvsched_vcpu_ops *)udata;
+ vm_ops = (struct pvsched_vcpu_ops *)kdata;
+
+ moff = __btf_member_bit_offset(t, member) / 8;
+ switch (moff) {
+ case offsetof(struct pvsched_vcpu_ops, events):
+ vm_ops->events = *(u32 *)(udata + moff);
+ return 1;
+ case offsetof(struct pvsched_vcpu_ops, name):
+ if (bpf_obj_name_cpy(vm_ops->name, uvm_ops->name,
+ sizeof(vm_ops->name)) <= 0)
+ return -EINVAL;
+ return 1;
+ }
+
+ return 0;
+}
+
+static int bpf_pvsched_vcpu_check_member(const struct btf_type *t,
+ const struct btf_member *member,
+ const struct bpf_prog *prog)
+{
+ return 0;
+}
+
+static int bpf_pvsched_vcpu_reg(void *kdata)
+{
+ return pvsched_register_vcpu_ops((struct pvsched_vcpu_ops *)kdata);
+}
+
+static void bpf_pvsched_vcpu_unreg(void *kdata)
+{
+ pvsched_unregister_vcpu_ops((struct pvsched_vcpu_ops *)kdata);
+}
+
+static int bpf_pvsched_vcpu_validate(void *kdata)
+{
+ return pvsched_validate_vcpu_ops((struct pvsched_vcpu_ops *)kdata);
+}
+
+static int bpf_pvsched_vcpu_update(void *kdata, void *old_kdata)
+{
+ return -EOPNOTSUPP;
+}
+
+static int __pvsched_vcpu_register(struct pid *pid)
+{
+ return 0;
+}
+static void __pvsched_vcpu_unregister(struct pid *pid)
+{
+}
+static void __pvsched_notify_event(void *addr, struct pid *pid, u32 event)
+{
+}
+
+static struct pvsched_vcpu_ops __bpf_ops_pvsched_vcpu_ops = {
+ .pvsched_vcpu_register = __pvsched_vcpu_register,
+ .pvsched_vcpu_unregister = __pvsched_vcpu_unregister,
+ .pvsched_vcpu_notify_event = __pvsched_notify_event,
+};
+
+struct bpf_struct_ops bpf_pvsched_vcpu_ops = {
+ .init = &bpf_pvsched_vcpu_init,
+ .validate = bpf_pvsched_vcpu_validate,
+ .update = bpf_pvsched_vcpu_update,
+ .verifier_ops = &bpf_pvsched_vcpu_verifier_ops,
+ .reg = bpf_pvsched_vcpu_reg,
+ .unreg = bpf_pvsched_vcpu_unreg,
+ .check_member = bpf_pvsched_vcpu_check_member,
+ .init_member = bpf_pvsched_vcpu_init_member,
+ .name = "pvsched_vcpu_ops",
+ .cfi_stubs = &__bpf_ops_pvsched_vcpu_ops,
+};
--
2.40.1
