* [PATCH v2 1/4] LoongArch: kexec: add KHO support for FDT-based systems
2026-05-29 14:32 George Guo
@ 2026-05-29 14:32 ` George Guo
2026-05-29 14:32 ` [PATCH v2 2/4] LoongArch: kexec: add KHO support for ACPI-only systems George Guo
` (3 subsequent siblings)
4 siblings, 0 replies; 12+ messages in thread
From: George Guo @ 2026-05-29 14:32 UTC (permalink / raw)
To: Huacai Chen, Mike Rapoport, Pasha Tatashin, Pratyush Yadav,
Shuah Khan
Cc: WANG Xuerui, Alexander Graf, loongarch, linux-kernel, kexec,
linux-mm, linux-kselftest, George Guo, Kexin Liu
From: George Guo <guodongtai@kylinos.cn>
Enable Kexec Handover (KHO) on LoongArch64 for FDT-based systems.
- Kconfig: select ARCH_SUPPORTS_KEXEC_HANDOVER for CONFIG_64BIT
- kexec.h: add fdt/fdt_mem fields to kimage_arch to hold the KHO FDT
kexec segment virtual and physical addresses
- machine_kexec_file.c: add kho_load_fdt() which copies the running
kernel's FDT (initial_boot_params), appends linux,kho-fdt and
linux,kho-scratch properties to /chosen, and loads the result as a
kexec segment; called from load_other_segments(). Returns -EINVAL
when initial_boot_params is NULL (ACPI-only boot) since that path
requires separate handling.
- machine_kexec.c: before jumping to the new kernel, update the
DEVICE_TREE_GUID entry in the EFI config table to point to the KHO
FDT segment so the second kernel finds it via efi_fdt_pointer() and
early_init_dt_check_kho() calls kho_populate()
Co-developed-by: Kexin Liu <liukexin@kylinos.cn>
Signed-off-by: Kexin Liu <liukexin@kylinos.cn>
Signed-off-by: George Guo <guodongtai@kylinos.cn>
---
arch/loongarch/Kconfig | 3 +
arch/loongarch/include/asm/kexec.h | 4 +
arch/loongarch/kernel/machine_kexec.c | 27 +++++
arch/loongarch/kernel/machine_kexec_file.c | 118 +++++++++++++++++++++
4 files changed, 152 insertions(+)
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 606597da46b8..d494418545f5 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -684,6 +684,9 @@ config ARCH_SUPPORTS_KEXEC
config ARCH_SUPPORTS_KEXEC_FILE
def_bool 64BIT
+config ARCH_SUPPORTS_KEXEC_HANDOVER
+ def_bool 64BIT
+
config ARCH_SELECTS_KEXEC_FILE
def_bool 64BIT
depends on KEXEC_FILE
diff --git a/arch/loongarch/include/asm/kexec.h b/arch/loongarch/include/asm/kexec.h
index 209fa43222e1..adf54bfcdd49 100644
--- a/arch/loongarch/include/asm/kexec.h
+++ b/arch/loongarch/include/asm/kexec.h
@@ -39,6 +39,10 @@ struct kimage_arch {
unsigned long efi_boot;
unsigned long cmdline_ptr;
unsigned long systable_ptr;
+#ifdef CONFIG_KEXEC_HANDOVER
+ void *fdt; /* virtual address of KHO FDT segment buffer */
+ unsigned long fdt_mem; /* physical address of KHO FDT segment */
+#endif
};
#ifdef CONFIG_KEXEC_FILE
diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
index d7fafda1d541..130f1adfa515 100644
--- a/arch/loongarch/kernel/machine_kexec.c
+++ b/arch/loongarch/kernel/machine_kexec.c
@@ -6,6 +6,7 @@
*/
#include <linux/compiler.h>
#include <linux/cpu.h>
+#include <linux/efi.h>
#include <linux/kexec.h>
#include <linux/crash_dump.h>
#include <linux/delay.h>
@@ -284,6 +285,32 @@ void machine_kexec(struct kimage *image)
pr_notice("We will call new kernel at 0x%lx\n", start_addr);
pr_notice("Bye ...\n");
+#ifdef CONFIG_KEXEC_HANDOVER
+ /*
+ * Point the EFI FDTPTR config table entry at the modified FDT so the
+ * second kernel picks up the linux,kho-fdt and linux,kho-scratch
+ * properties via early_init_dt_check_kho().
+ */
+ if (internal->fdt_mem) {
+ /*
+ * FDT-based system: DEVICE_TREE_GUID already exists in the EFI
+ * config table; just update its pointer to our KHO FDT.
+ */
+ efi_system_table_t *st =
+ (efi_system_table_t *)TO_CACHE(systable_ptr);
+ efi_config_table_t *ct =
+ (efi_config_table_t *)TO_CACHE((unsigned long)st->tables);
+ unsigned long i;
+
+ for (i = 0; i < st->nr_tables; i++) {
+ if (!efi_guidcmp(ct[i].guid, DEVICE_TREE_GUID)) {
+ ct[i].table = (void *)internal->fdt_mem;
+ break;
+ }
+ }
+ }
+#endif
+
/* Make reboot code buffer available to the boot CPU. */
flush_cache_all();
diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
index 5584b798ba46..bf1e8c1c7e70 100644
--- a/arch/loongarch/kernel/machine_kexec_file.c
+++ b/arch/loongarch/kernel/machine_kexec_file.c
@@ -13,7 +13,9 @@
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/kexec.h>
+#include <linux/libfdt.h>
#include <linux/memblock.h>
+#include <linux/of_fdt.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/types.h>
@@ -32,6 +34,11 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
image->elf_headers = NULL;
image->elf_headers_sz = 0;
+#ifdef CONFIG_KEXEC_HANDOVER
+ kvfree(image->arch.fdt);
+ image->arch.fdt = NULL;
+#endif
+
return kexec_image_post_load_cleanup_default(image);
}
@@ -55,6 +62,111 @@ static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmpl
*cmdline_tmplen += initrd_strlen;
}
+#ifdef CONFIG_KEXEC_HANDOVER
+/*
+ * Add KHO metadata to an FDT /chosen node and load the FDT as a kexec
+ * segment. The second kernel reads linux,kho-fdt and linux,kho-scratch
+ * from /chosen via early_init_dt_check_kho() and calls kho_populate().
+ *
+ */
+static int kho_load_fdt(struct kimage *image)
+{
+ void *fdt;
+ int ret, chosen_node;
+ size_t fdt_size;
+ struct kexec_buf kbuf = {
+ .image = image,
+ .buf_min = 0,
+ .buf_max = ULONG_MAX,
+ .top_down = true,
+ };
+
+ if (!image->kho.fdt || !image->kho.scratch)
+ return 0;
+
+ if (initial_boot_params) {
+ /*
+ * FDT boot: copy the running kernel's FDT and append KHO
+ * properties to /chosen.
+ */
+
+ /*
+ * Only two KHO properties are added to /chosen (linux,kho-fdt
+ * and linux,kho-scratch), so SZ_1K of extra space is
+ * sufficient.
+ */
+ fdt_size = fdt_totalsize(initial_boot_params) + SZ_1K;
+ fdt = kvmalloc(fdt_size, GFP_KERNEL);
+ if (!fdt)
+ return -ENOMEM;
+
+ ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
+ if (ret < 0) {
+ pr_err("Failed to open FDT: %d\n", ret);
+ goto out_free;
+ }
+
+ chosen_node = fdt_path_offset(fdt, "/chosen");
+ if (chosen_node == -FDT_ERR_NOTFOUND) {
+ pr_debug("No /chosen node in FDT, creating one\n");
+ chosen_node = fdt_add_subnode(fdt,
+ fdt_path_offset(fdt, "/"),
+ "chosen");
+ }
+ if (chosen_node < 0) {
+ ret = chosen_node;
+ goto out_free;
+ }
+
+ /* Remove stale KHO properties left by a previous kexec load */
+ fdt_delprop(fdt, chosen_node, "linux,kho-fdt");
+ fdt_delprop(fdt, chosen_node, "linux,kho-scratch");
+
+ ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
+ "linux,kho-fdt",
+ image->kho.fdt, PAGE_SIZE);
+ if (ret)
+ goto out_free;
+
+ ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
+ "linux,kho-scratch",
+ image->kho.scratch->mem,
+ image->kho.scratch->bufsz);
+ if (ret)
+ goto out_free;
+
+ /*
+ * Shrink totalsize to the actual data size so the kexec segment
+ * allocated by kexec_add_buffer() covers only the packed FDT data.
+ * The slack added above for property insertion is part of the
+ * kvmalloc'd buffer, which is freed by kimage_file_post_load_cleanup()
+ * once the kexec image has been loaded.
+ */
+ fdt_pack(fdt);
+
+ kbuf.buffer = fdt;
+ kbuf.bufsz = fdt_totalsize(fdt);
+ kbuf.memsz = kbuf.bufsz;
+ kbuf.buf_align = PAGE_SIZE;
+ kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
+
+ ret = kexec_add_buffer(&kbuf);
+ if (ret)
+ goto out_free;
+
+ image->arch.fdt = fdt;
+ image->arch.fdt_mem = kbuf.mem;
+ return 0;
+ } else {
+ return -EINVAL;
+ }
+
+out_free:
+ kvfree(fdt);
+ return ret;
+}
+#endif
+
#ifdef CONFIG_CRASH_DUMP
static int prepare_elf_headers(void **addr, unsigned long *sz)
@@ -230,6 +342,12 @@ int load_other_segments(struct kimage *image,
cmdline = modified_cmdline;
image->arch.cmdline_ptr = (unsigned long)cmdline;
+#ifdef CONFIG_KEXEC_HANDOVER
+ ret = kho_load_fdt(image);
+ if (ret)
+ goto out_err;
+#endif
+
return 0;
out_err:
--
2.25.1
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v2 2/4] LoongArch: kexec: add KHO support for ACPI-only systems
2026-05-29 14:32 George Guo
2026-05-29 14:32 ` [PATCH v2 1/4] LoongArch: kexec: add KHO support for FDT-based systems George Guo
@ 2026-05-29 14:32 ` George Guo
2026-05-29 14:32 ` [PATCH v2 3/4] selftests/kho: add LoongArch vmtest support George Guo
` (2 subsequent siblings)
4 siblings, 0 replies; 12+ messages in thread
From: George Guo @ 2026-05-29 14:32 UTC (permalink / raw)
To: Huacai Chen, Mike Rapoport, Pasha Tatashin, Pratyush Yadav,
Shuah Khan
Cc: WANG Xuerui, Alexander Graf, loongarch, linux-kernel, kexec,
linux-mm, linux-kselftest, George Guo
From: George Guo <guodongtai@kylinos.cn>
On ACPI-only systems fdt_setup() returns early when it detects ACPI,
so initial_boot_params remains NULL and the FDT-based kho_load_fdt()
path cannot be used.
machine_kexec_file.c:
- kho_load_fdt(): add an else branch that builds a minimal FDT from
scratch (SZ_1K) containing only a /chosen node with linux,kho-fdt
and linux,kho-scratch properties, using the libfdt creation API.
- Since DEVICE_TREE_GUID is absent from the EFI config table on
ACPI-only systems, build a new config table with DEVICE_TREE_GUID
appended and load it as a kexec segment. Store the result in
kimage_arch so machine_kexec() can switch st->tables before jumping.
- arch_kimage_file_post_load_cleanup(): free the efi_tables kvmalloc
buffer once the kexec image has been loaded.
machine_kexec.c:
- Before jumping, update the EFI system table pointer: for FDT-based
systems update the existing DEVICE_TREE_GUID entry; for ACPI-only
systems switch st->tables / st->nr_tables to the new extended table.
setup.c:
- fdt_setup(): when ACPI is detected, use efi_fdt_pointer() to detect
whether this is a KHO kexec boot. The first kernel switches the EFI
config table to a new one that includes a DEVICE_TREE_GUID entry
pointing to the minimal KHO FDT. If found, call early_init_dt_scan()
so early_init_dt_check_kho() can consume linux,kho-fdt and
linux,kho-scratch, then reset initial_boot_params to NULL so the rest
of the ACPI boot path is unaffected.
kexec.h:
- Add efi_tables, efi_tables_mem, efi_tables_cnt to kimage_arch.
Signed-off-by: George Guo <guodongtai@kylinos.cn>
---
arch/loongarch/include/asm/kexec.h | 3 +
arch/loongarch/kernel/machine_kexec.c | 11 ++
arch/loongarch/kernel/machine_kexec_file.c | 162 +++++++++++++++++++--
arch/loongarch/kernel/setup.c | 21 ++-
4 files changed, 184 insertions(+), 13 deletions(-)
diff --git a/arch/loongarch/include/asm/kexec.h b/arch/loongarch/include/asm/kexec.h
index adf54bfcdd49..e1abaf40b06a 100644
--- a/arch/loongarch/include/asm/kexec.h
+++ b/arch/loongarch/include/asm/kexec.h
@@ -42,6 +42,9 @@ struct kimage_arch {
#ifdef CONFIG_KEXEC_HANDOVER
void *fdt; /* virtual address of KHO FDT segment buffer */
unsigned long fdt_mem; /* physical address of KHO FDT segment */
+ void *efi_tables; /* new EFI config table buffer (virtual) */
+ unsigned long efi_tables_mem; /* physical address of new EFI config table */
+ unsigned long efi_tables_cnt; /* number of entries in new EFI config table */
#endif
};
diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
index 130f1adfa515..4ee9a433d2de 100644
--- a/arch/loongarch/kernel/machine_kexec.c
+++ b/arch/loongarch/kernel/machine_kexec.c
@@ -308,6 +308,17 @@ void machine_kexec(struct kimage *image)
break;
}
}
+ } else if (internal->efi_tables_mem) {
+ /*
+ * ACPI-only system: DEVICE_TREE_GUID was not in the original
+ * EFI config table. Switch to the new table that was built in
+ * kho_load_fdt() with DEVICE_TREE_GUID appended.
+ */
+ efi_system_table_t *st =
+ (efi_system_table_t *)TO_CACHE(systable_ptr);
+
+ st->tables = internal->efi_tables_mem;
+ st->nr_tables = internal->efi_tables_cnt;
}
#endif
diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
index bf1e8c1c7e70..c1955d991061 100644
--- a/arch/loongarch/kernel/machine_kexec_file.c
+++ b/arch/loongarch/kernel/machine_kexec_file.c
@@ -10,6 +10,7 @@
#define pr_fmt(fmt) "kexec_file: " fmt
+#include <linux/efi.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/kexec.h>
@@ -20,6 +21,7 @@
#include <linux/string.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
+#include <asm/addrspace.h>
#include <asm/bootinfo.h>
const struct kexec_file_ops * const kexec_file_loaders[] = {
@@ -37,6 +39,8 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
#ifdef CONFIG_KEXEC_HANDOVER
kvfree(image->arch.fdt);
image->arch.fdt = NULL;
+ kvfree(image->arch.efi_tables);
+ image->arch.efi_tables = NULL;
#endif
return kexec_image_post_load_cleanup_default(image);
@@ -68,6 +72,13 @@ static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmpl
* segment. The second kernel reads linux,kho-fdt and linux,kho-scratch
* from /chosen via early_init_dt_check_kho() and calls kho_populate().
*
+ * On FDT-based systems (initial_boot_params != NULL), the current FDT is
+ * copied and the KHO properties are appended to /chosen.
+ *
+ * On ACPI-only systems (initial_boot_params == NULL), a minimal FDT
+ * containing only /chosen is built from scratch. machine_kexec() updates
+ * the EFI config table DEVICE_TREE_GUID entry to point to this segment so
+ * that the second kernel's fdt_setup() can find and parse it.
*/
static int kho_load_fdt(struct kimage *image)
{
@@ -143,24 +154,151 @@ static int kho_load_fdt(struct kimage *image)
* once the kexec image has been loaded.
*/
fdt_pack(fdt);
+ } else {
+ /*
+ * ACPI boot: build a minimal FDT containing only /chosen with
+ * the two KHO properties. No system FDT is available to copy.
+ */
- kbuf.buffer = fdt;
- kbuf.bufsz = fdt_totalsize(fdt);
- kbuf.memsz = kbuf.bufsz;
- kbuf.buf_align = PAGE_SIZE;
- kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
+ __be64 prop[2];
- ret = kexec_add_buffer(&kbuf);
- if (ret)
+ fdt_size = SZ_1K;
+ fdt = kvmalloc(fdt_size, GFP_KERNEL);
+ if (!fdt)
+ return -ENOMEM;
+
+ ret = fdt_create(fdt, fdt_size);
+ if (ret < 0)
+ goto out_free;
+ ret = fdt_finish_reservemap(fdt);
+ if (ret < 0)
+ goto out_free;
+ ret = fdt_begin_node(fdt, ""); /* root */
+ if (ret < 0)
+ goto out_free;
+ ret = fdt_property_u32(fdt, "#address-cells", 2);
+ if (ret < 0)
+ goto out_free;
+ ret = fdt_property_u32(fdt, "#size-cells", 2);
+ if (ret < 0)
+ goto out_free;
+ ret = fdt_begin_node(fdt, "chosen");
+ if (ret < 0)
goto out_free;
- image->arch.fdt = fdt;
- image->arch.fdt_mem = kbuf.mem;
- return 0;
- } else {
- return -EINVAL;
+ prop[0] = cpu_to_be64(image->kho.fdt);
+ prop[1] = cpu_to_be64(PAGE_SIZE);
+ ret = fdt_property(fdt, "linux,kho-fdt", prop, sizeof(prop));
+ if (ret < 0)
+ goto out_free;
+
+ prop[0] = cpu_to_be64(image->kho.scratch->mem);
+ prop[1] = cpu_to_be64(image->kho.scratch->bufsz);
+ ret = fdt_property(fdt, "linux,kho-scratch", prop, sizeof(prop));
+ if (ret < 0)
+ goto out_free;
+
+ ret = fdt_end_node(fdt); /* chosen */
+ if (ret < 0)
+ goto out_free;
+ ret = fdt_end_node(fdt); /* root */
+ if (ret < 0)
+ goto out_free;
+ ret = fdt_finish(fdt);
+ if (ret < 0)
+ goto out_free;
}
+ kbuf.buffer = fdt;
+ kbuf.bufsz = fdt_totalsize(fdt);
+ kbuf.memsz = kbuf.bufsz;
+ kbuf.buf_align = PAGE_SIZE;
+ kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
+
+ ret = kexec_add_buffer(&kbuf);
+ if (ret)
+ goto out_free;
+
+ image->arch.fdt = fdt;
+ image->arch.fdt_mem = kbuf.mem;
+
+ /*
+ * On ACPI-only systems DEVICE_TREE_GUID is not in the EFI config
+ * table, so the second kernel's efi_fdt_pointer() cannot locate the
+ * KHO FDT. Build a new EFI config table with DEVICE_TREE_GUID added
+ * and load it as a kexec segment; machine_kexec() will update
+ * st->tables / st->nr_tables to point to it before jumping.
+ */
+
+ /*
+ * fw_arg2 is the EFI system table physical address passed by the
+ * firmware/bootloader. Use it directly here because
+ * image->arch.systable_ptr is set later in machine_kexec_prepare(),
+ * which runs after load_other_segments() / kho_load_fdt().
+ */
+ if (!initial_boot_params && fw_arg2) {
+ efi_system_table_t *st =
+ (efi_system_table_t *)TO_CACHE(fw_arg2);
+ efi_config_table_t *ct =
+ (efi_config_table_t *)TO_CACHE((unsigned long)st->tables);
+ unsigned long i;
+ bool found = false;
+
+ /*
+ * Scan the original config table;
+ * DEVICE_TREE_GUID is absent on ACPI-only systems.
+ */
+ for (i = 0; i < st->nr_tables; i++) {
+ if (!efi_guidcmp(ct[i].guid, DEVICE_TREE_GUID)) {
+ found = true;
+ break;
+ }
+ }
+
+ if (!found) {
+ size_t old_sz = st->nr_tables * sizeof(efi_config_table_t);
+ size_t new_sz = old_sz + sizeof(efi_config_table_t);
+ efi_config_table_t *new_ct;
+ struct kexec_buf tbuf = {
+ .image = image,
+ .buf_min = 0,
+ .buf_max = ULONG_MAX,
+ .top_down = true,
+ };
+
+ /*
+ * Allocate a new table with n+1 entries and append
+ * the DEVICE_TREE_GUID entry.
+ */
+ new_ct = kvmalloc(new_sz, GFP_KERNEL);
+ if (!new_ct)
+ return -ENOMEM;
+
+ memcpy(new_ct, ct, old_sz);
+ new_ct[st->nr_tables].guid = DEVICE_TREE_GUID;
+ new_ct[st->nr_tables].table = (void *)image->arch.fdt_mem;
+
+ /* Register the new config table as a kexec segment. */
+ tbuf.buffer = new_ct;
+ tbuf.bufsz = new_sz;
+ tbuf.memsz = new_sz;
+ tbuf.buf_align = sizeof(void *);
+ tbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
+
+ ret = kexec_add_buffer(&tbuf);
+ if (ret) {
+ kvfree(new_ct);
+ return ret;
+ }
+
+ image->arch.efi_tables = new_ct;
+ image->arch.efi_tables_mem = tbuf.mem;
+ image->arch.efi_tables_cnt = st->nr_tables + 1;
+ }
+ }
+
+ return 0;
+
out_free:
kvfree(fdt);
return ret;
diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 839b23edee87..c82067d1dc75 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -286,8 +286,27 @@ static void __init fdt_setup(void)
void *fdt_pointer;
/* ACPI-based systems do not require parsing fdt */
- if (acpi_os_get_root_pointer())
+ if (acpi_os_get_root_pointer()) {
+#ifdef CONFIG_KEXEC_HANDOVER
+ /*
+ * On a KHO kexec boot the first kernel builds a minimal FDT
+ * containing only /chosen with linux,kho-fdt and
+ * linux,kho-scratch, and switches the EFI config table to a
+ * new one that includes a DEVICE_TREE_GUID entry pointing to
+ * it. Use efi_fdt_pointer() to detect this case.
+ *
+ * Call early_init_dt_scan() to let early_init_dt_check_kho()
+ * consume the KHO data, then reset initial_boot_params so the
+ * rest of the ACPI boot path is not confused by this FDT.
+ */
+ fdt_pointer = efi_fdt_pointer();
+ if (fdt_pointer && !fdt_check_header(fdt_pointer)) {
+ early_init_dt_scan(fdt_pointer, __pa(fdt_pointer));
+ initial_boot_params = NULL;
+ }
+#endif
return;
+ }
/* Prefer to use built-in dtb, checking its legality first. */
if (IS_ENABLED(CONFIG_BUILTIN_DTB) && !fdt_check_header(__dtb_start))
--
2.25.1
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v2 3/4] selftests/kho: add LoongArch vmtest support
2026-05-29 14:32 George Guo
2026-05-29 14:32 ` [PATCH v2 1/4] LoongArch: kexec: add KHO support for FDT-based systems George Guo
2026-05-29 14:32 ` [PATCH v2 2/4] LoongArch: kexec: add KHO support for ACPI-only systems George Guo
@ 2026-05-29 14:32 ` George Guo
2026-05-29 14:32 ` [PATCH v2 4/4] selftests/kho: handle QEMU not exiting after kexec on LoongArch George Guo
2026-05-31 9:28 ` Mike Rapoport
4 siblings, 0 replies; 12+ messages in thread
From: George Guo @ 2026-05-29 14:32 UTC (permalink / raw)
To: Huacai Chen, Mike Rapoport, Pasha Tatashin, Pratyush Yadav,
Shuah Khan
Cc: WANG Xuerui, Alexander Graf, loongarch, linux-kernel, kexec,
linux-mm, linux-kselftest, George Guo, Kexin Liu
From: George Guo <guodongtai@kylinos.cn>
Add loongarch.conf to configure QEMU's LoongArch virt machine with a
la464 CPU, enable the 8250 serial console, and set the kernel image
to vmlinux.efi. Extend vmtest.sh to recognize loongarch64 as a
supported target and map it to the 'loongarch' kernel arch name.
QEMU's LoongArch virt machine provides no ACPI tables and relies on
FDT to describe hardware. Without 'earlycon' on the kernel command
line, the FDT is not scanned for a console UART, no output reaches
the console, and vmtest.sh's console log stays empty causing the test
to always fail. Add 'earlycon' to KERNEL_CMDLINE in loongarch.conf
to fix this.
QEMU's LoongArch virt machine has no i8042 PS/2 controller. When PNP
detection finds nothing, i8042_init() falls back to probing the ports
directly. On LoongArch the I/O ports are memory-mapped, and the i8042
port addresses are not backed by any device on the virt machine, so
i8042_flush() takes a page fault and the kernel panics:
i8042: PNP: No PS/2 controller found.
i8042: Probing ports directly.
CPU 0 Unable to handle kernel paging request at virtual address ffff800000008064
ERA: i8042_flush+0x50/0x198
RA: i8042_init+0x2a8/0x35c
Kernel panic - not syncing: Attempted to kill init!
Disable SERIO_I8042 and its dependents (KEYBOARD_ATKBD, MOUSE_PS2) in
the QEMU_KCONFIG fragment to prevent the driver from being built.
Co-developed-by: Kexin Liu <liukexin@kylinos.cn>
Signed-off-by: Kexin Liu <liukexin@kylinos.cn>
Signed-off-by: George Guo <guodongtai@kylinos.cn>
---
tools/testing/selftests/kho/loongarch.conf | 10 ++++++++++
tools/testing/selftests/kho/vmtest.sh | 3 ++-
2 files changed, 12 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/kho/loongarch.conf
diff --git a/tools/testing/selftests/kho/loongarch.conf b/tools/testing/selftests/kho/loongarch.conf
new file mode 100644
index 000000000000..0145cb49e5b2
--- /dev/null
+++ b/tools/testing/selftests/kho/loongarch.conf
@@ -0,0 +1,10 @@
+QEMU_CMD="qemu-system-loongarch64 -M virt -cpu la464"
+QEMU_KCONFIG="
+CONFIG_SERIAL_8250=y
+CONFIG_SERIAL_8250_CONSOLE=y
+# CONFIG_KEYBOARD_ATKBD is not set
+# CONFIG_MOUSE_PS2 is not set
+# CONFIG_SERIO_I8042 is not set
+"
+KERNEL_IMAGE="vmlinux.efi"
+KERNEL_CMDLINE="console=ttyS0 earlycon"
diff --git a/tools/testing/selftests/kho/vmtest.sh b/tools/testing/selftests/kho/vmtest.sh
index 49fdac8e8b15..a6ae9ac09595 100755
--- a/tools/testing/selftests/kho/vmtest.sh
+++ b/tools/testing/selftests/kho/vmtest.sh
@@ -21,7 +21,7 @@ Options:
-d) path to the kernel build directory
-j) number of jobs for compilation, similar to -j in make
-t) run test for target_arch, requires CROSS_COMPILE set
- supported targets: aarch64, x86_64
+ supported targets: aarch64, x86_64, loongarch64
-h) display this help
EOF
}
@@ -123,6 +123,7 @@ function target_to_arch() {
case $target in
aarch64) echo "arm64" ;;
x86_64) echo "x86" ;;
+ loongarch64) echo "loongarch" ;;
*) skip "architecture $target is not supported"
esac
}
--
2.25.1
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v2 4/4] selftests/kho: handle QEMU not exiting after kexec on LoongArch
2026-05-29 14:32 George Guo
` (2 preceding siblings ...)
2026-05-29 14:32 ` [PATCH v2 3/4] selftests/kho: add LoongArch vmtest support George Guo
@ 2026-05-29 14:32 ` George Guo
2026-05-31 9:28 ` Mike Rapoport
4 siblings, 0 replies; 12+ messages in thread
From: George Guo @ 2026-05-29 14:32 UTC (permalink / raw)
To: Huacai Chen, Mike Rapoport, Pasha Tatashin, Pratyush Yadav,
Shuah Khan
Cc: WANG Xuerui, Alexander Graf, loongarch, linux-kernel, kexec,
linux-mm, linux-kselftest, George Guo
From: George Guo <guodongtai@kylinos.cn>
On LoongArch, QEMU provides only a minimal EFI stub with no runtime
services and no ACPI tables, so machine_restart() falls through to
its infinite idle loop and QEMU never exits after kexec. The test
result is already printed to the serial console and vmtest.sh reports
success, but the user must press Ctrl+C to get the prompt back.
Add QEMU_NEEDS_KILL=1 to loongarch.conf so the test completes
unattended.
Signed-off-by: George Guo <guodongtai@kylinos.cn>
---
tools/testing/selftests/kho/loongarch.conf | 3 ++
tools/testing/selftests/kho/vmtest.sh | 32 ++++++++++++++++++----
2 files changed, 29 insertions(+), 6 deletions(-)
diff --git a/tools/testing/selftests/kho/loongarch.conf b/tools/testing/selftests/kho/loongarch.conf
index 0145cb49e5b2..02a6add633f1 100644
--- a/tools/testing/selftests/kho/loongarch.conf
+++ b/tools/testing/selftests/kho/loongarch.conf
@@ -8,3 +8,6 @@ CONFIG_SERIAL_8250_CONSOLE=y
"
KERNEL_IMAGE="vmlinux.efi"
KERNEL_CMDLINE="console=ttyS0 earlycon"
+# QEMU never exits after kexec on LoongArch (no EFI runtime services),
+# so vmtest.sh must kill it once the test verdict appears.
+QEMU_NEEDS_KILL=1
diff --git a/tools/testing/selftests/kho/vmtest.sh b/tools/testing/selftests/kho/vmtest.sh
index a6ae9ac09595..821e13fa69a5 100755
--- a/tools/testing/selftests/kho/vmtest.sh
+++ b/tools/testing/selftests/kho/vmtest.sh
@@ -107,12 +107,32 @@ function run_qemu() {
cmdline="$cmdline kho=on panic=-1"
- $qemu_cmd -m 1G -smp 2 -no-reboot -nographic -nodefaults \
- -accel kvm -accel hvf -accel tcg \
- -serial file:"$serial" \
- -append "$cmdline" \
- -kernel "$kernel" \
- -initrd "$initrd"
+ local qemu_args=(
+ -m 1G -smp 2 -no-reboot -nographic -nodefaults
+ -accel kvm -accel hvf -accel tcg
+ -serial file:"$serial"
+ -append "$cmdline"
+ -kernel "$kernel"
+ -initrd "$initrd"
+ )
+
+ # If the target does not exit QEMU after kexec (e.g. no EFI runtime
+ # services), the conf file sets QEMU_NEEDS_KILL=1. Run QEMU in the
+ # background, poll for the test verdict, then kill it.
+ if [[ "${QEMU_NEEDS_KILL:-0}" == "1" ]]; then
+ $qemu_cmd "${qemu_args[@]}" &
+ local qemu_pid=$!
+ local remaining=100
+ while ((remaining-- > 0)); do
+ grep -q "KHO restore succeeded\|KHO restore failed" \
+ "$serial" 2>/dev/null && break
+ sleep 1
+ done
+ kill "$qemu_pid" 2>/dev/null
+ wait "$qemu_pid" 2>/dev/null || true
+ else
+ $qemu_cmd "${qemu_args[@]}"
+ fi
grep "KHO restore succeeded" "$serial" &> /dev/null || fail "KHO failed"
}
--
2.25.1
^ permalink raw reply related [flat|nested] 12+ messages in thread* Re:
2026-05-29 14:32 George Guo
` (3 preceding siblings ...)
2026-05-29 14:32 ` [PATCH v2 4/4] selftests/kho: handle QEMU not exiting after kexec on LoongArch George Guo
@ 2026-05-31 9:28 ` Mike Rapoport
4 siblings, 0 replies; 12+ messages in thread
From: Mike Rapoport @ 2026-05-31 9:28 UTC (permalink / raw)
To: George Guo
Cc: Huacai Chen, Pasha Tatashin, Pratyush Yadav, Shuah Khan,
WANG Xuerui, Alexander Graf, loongarch, linux-kernel, kexec,
linux-mm, linux-kselftest, George Guo
Hi,
On Fri, May 29, 2026 at 10:32:34PM +0800, George Guo wrote:
> From: George Guo <guodongtai@kylinos.cn>
>
> WARNING: Prefer a maximum 75 chars per line (possible unwrapped commit description?)
> #26:
> containing only /chosen with the two KHO properties. Since DEVICE_TREE_GUID
>
> ERROR: Invalid commit separator - some tools may have problems applying this
> #34:
> -------------------------------
>
> total: 2 errors, 1 warnings, 0 lines checked
I believe something went wrong with sending the emails :)
Please include changes from revision to revision in the cover letter next
time.
You also may want to consider using b4 prep/send for sending the patches.
> >
> Date: Fri, 29 May 2026 21:54:01 +0800
> Subject: [PATCH v2 0/4] LoongArch: add KHO support and selftests
>
> This series adds Kexec Handover (KHO) support for LoongArch and extends
> the KHO selftest infrastructure to run on LoongArch under QEMU.
>
> KHO passes metadata (the KHO state FDT and scratch area addresses) to the
> second kernel via the FDT /chosen node, using the linux,kho-fdt and
> linux,kho-scratch properties that drivers/of/kexec.c:kho_add_chosen()
> writes and drivers/of/fdt.c:early_init_dt_check_kho() reads.
>
> Selftest support (patches 3-4):
>
> Patch 3 adds loongarch.conf and extends vmtest.sh to recognise loongarch64
> as a build target. The LoongArch virt machine is FDT-only (no ACPI), so
> 'earlycon' must appear on the kernel cmdline or the console UART is never
> discovered. PS/2 input devices are also disabled since QEMU's LoongArch
> virt machine has no i8042 controller; the fallback port probe hits a page
> fault and panics before reaching userspace.
Patch 3 should not introduce regressions
> Patch 4 handles QEMU not exiting after kexec on LoongArch. QEMU provides
> no EFI runtime services, so machine_restart() falls through to an infinite
> idle loop. QEMU_NEEDS_KILL=1 in loongarch.conf signals vmtest.sh to run
> QEMU in the background, poll the serial output for the test verdict, and
> kill QEMU once it appears, so the test completes unattended.
And patch 4 should be folded into patch 3.
As I said during v1 review, the whole wait and kill loop can be replaced
with 'timeout' command which does not need to be specific for LoongArch.
The actual timeout value might, though.
Will wait for v3 for more detailed review.
> George Guo (4):
> LoongArch: kexec: add KHO support for FDT-based systems
> LoongArch: kexec: add KHO support for ACPI-only systems
> selftests/kho: add LoongArch vmtest support
> selftests/kho: handle QEMU not exiting after kexec on LoongArch
>
> arch/loongarch/Kconfig | 3 +
> arch/loongarch/include/asm/kexec.h | 7 +
> arch/loongarch/kernel/machine_kexec.c | 38 +++
> arch/loongarch/kernel/machine_kexec_file.c | 256 +++++++++++++++++++++
> arch/loongarch/kernel/setup.c | 21 +-
> tools/testing/selftests/kho/loongarch.conf | 13 ++
> tools/testing/selftests/kho/vmtest.sh | 35 ++-
> 7 files changed, 365 insertions(+), 8 deletions(-)
> create mode 100644 tools/testing/selftests/kho/loongarch.conf
>
> --
> 2.25.1
>
>
--
Sincerely yours,
Mike.
^ permalink raw reply [flat|nested] 12+ messages in thread