Re: [PATCHv7 1/7] kho: allow to drive kho from within kernel

On Tue, Oct 21, 2025 at 08:57:13PM -0400, Pasha Tatashin wrote:

Allow kernel to drive finalize and abort without requiring triggers from the userspace.

Signed-off-by: Pasha Tatashin pasha.tatashin@soleen.com Reviewed-by: Pratyush Yadav pratyush@kernel.org

Reviewed-by: Mike Rapoport (Microsoft) rppt@kernel.org

---

include/linux/kexec_handover.h | 15 +++++++ kernel/kexec_handover.c | 75 +++++++++++++++++++++------------- 2 files changed, 61 insertions(+), 29 deletions(-)

diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h index 25042c1d8d54..04d0108db98e 100644 --- a/include/linux/kexec_handover.h +++ b/include/linux/kexec_handover.h @@ -67,6 +67,10 @@ void kho_memory_init(void); void kho_populate(phys_addr_t fdt_phys, u64 fdt_len, phys_addr_t scratch_phys, u64 scratch_len);

+int kho_finalize(void); +int kho_abort(void);

#else static inline bool kho_is_enabled(void) { @@ -139,6 +143,17 @@ static inline void kho_populate(phys_addr_t fdt_phys, u64 fdt_len, phys_addr_t scratch_phys, u64 scratch_len) { }

+static inline int kho_finalize(void) +{

• return -EOPNOTSUPP;

+}

+static inline int kho_abort(void) +{

• return -EOPNOTSUPP;

+}

#endif /* CONFIG_KEXEC_HANDOVER */ #endif /* LINUX_KEXEC_HANDOVER_H */ diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c index de4466b47455..6458f369a346 100644 --- a/kernel/kexec_handover.c +++ b/kernel/kexec_handover.c @@ -1087,7 +1087,7 @@ static int kho_out_update_debugfs_fdt(void) return err; } -static int kho_abort(void) +static int __kho_abort(void) { int err; unsigned long order; @@ -1120,7 +1120,27 @@ static int kho_abort(void) return err; } -static int kho_finalize(void) +int kho_abort(void) +{

• int ret = 0;
• if (!kho_enable)

• return -EOPNOTSUPP;
  

• guard(mutex)(&kho_out.lock);
• if (!kho_out.finalized)

• return -ENOENT;
  

• ret = __kho_abort();
• if (ret)

• return ret;
  

• kho_out.finalized = false;
• return kho_out_update_debugfs_fdt();

+}

+static int __kho_finalize(void) { int err = 0; u64 *preserved_mem_map; @@ -1163,12 +1183,32 @@ static int kho_finalize(void) abort: if (err) { pr_err("Failed to convert KHO state tree: %d\n", err);

• kho_abort();
  

• __kho_abort();
  

  }

return err; } +int kho_finalize(void) +{

• int ret;
• if (!kho_enable)

• return -EOPNOTSUPP;
  

• guard(mutex)(&kho_out.lock);
• if (kho_out.finalized)

• return -EEXIST;
  

• ret = __kho_finalize();
• if (ret)

• return ret;
  

• kho_out.finalized = true;
• return kho_out_update_debugfs_fdt();

+}

static int kho_out_finalize_get(void *data, u64 *val) { mutex_lock(&kho_out.lock); @@ -1178,35 +1218,12 @@ static int kho_out_finalize_get(void *data, u64 *val) return 0; } -static int kho_out_finalize_set(void *data, u64 _val) +static int kho_out_finalize_set(void *data, u64 val) {

• int ret = 0;
• bool val = !!_val;
• mutex_lock(&kho_out.lock);
• if (val == kho_out.finalized) {

• if (kho_out.finalized)
  

• 	ret = -EEXIST;
  

• else
  

• 	ret = -ENOENT;
  

• goto unlock;
  

• }
• if (val)

• ret = kho_finalize();
  

• return kho_finalize();
  

  else

• ret = kho_abort();
  

• if (ret)

• goto unlock;
  

• kho_out.finalized = val;
• ret = kho_out_update_debugfs_fdt();

-unlock:

• mutex_unlock(&kho_out.lock);
• return ret;

• return kho_abort();
  

} DEFINE_DEBUGFS_ATTRIBUTE(fops_kho_out_finalize, kho_out_finalize_get, -- 2.51.0.915.g61a8936c21-goog