[PATCH v5 12/16] arm64: add KHO support

[Changyuan Lyu <changyuanl@google.com>]

From: Alexander Graf <graf@amazon.com>

We now have all bits in place to support KHO kexecs. Add awareness of
KHO in the kexec file as well as boot path for arm64 and adds the
respective kconfig option to the architecture so that it can use KHO
successfully.

Signed-off-by: Alexander Graf <graf@amazon.com>
Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Co-developed-by: Changyuan Lyu <changyuanl@google.com>
Signed-off-by: Changyuan Lyu <changyuanl@google.com>
---
 arch/arm64/Kconfig |  3 +++
 drivers/of/fdt.c   | 33 +++++++++++++++++++++++++++++++++
 drivers/of/kexec.c | 37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 73 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 940343beb3d4..c997b27b7da1 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1589,6 +1589,9 @@ config ARCH_SUPPORTS_KEXEC_IMAGE_VERIFY_SIG
 config ARCH_DEFAULT_KEXEC_IMAGE_VERIFY_SIG
 	def_bool y
 
+config ARCH_SUPPORTS_KEXEC_HANDOVER
+	def_bool y
+
 config ARCH_SUPPORTS_CRASH_DUMP
 	def_bool y
 
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index aedd0e2dcd89..73f80e3f7188 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -25,6 +25,7 @@
 #include <linux/serial_core.h>
 #include <linux/sysfs.h>
 #include <linux/random.h>
+#include <linux/kexec_handover.h>
 
 #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
 #include <asm/page.h>
@@ -875,6 +876,35 @@ void __init early_init_dt_check_for_usable_mem_range(void)
 		memblock_add(rgn[i].base, rgn[i].size);
 }
 
+/**
+ * early_init_dt_check_kho - Decode info required for kexec handover from DT
+ */
+static void __init early_init_dt_check_kho(void)
+{
+	unsigned long node = chosen_node_offset;
+	u64 kho_start, scratch_start, scratch_size;
+	const __be32 *p;
+	int l;
+
+	if (!IS_ENABLED(CONFIG_KEXEC_HANDOVER) || (long)node < 0)
+		return;
+
+	p = of_get_flat_dt_prop(node, "linux,kho-fdt", &l);
+	if (l != (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32))
+		return;
+
+	kho_start = dt_mem_next_cell(dt_root_addr_cells, &p);
+
+	p = of_get_flat_dt_prop(node, "linux,kho-scratch", &l);
+	if (l != (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32))
+		return;
+
+	scratch_start = dt_mem_next_cell(dt_root_addr_cells, &p);
+	scratch_size = dt_mem_next_cell(dt_root_addr_cells, &p);
+
+	kho_populate(kho_start, scratch_start, scratch_size);
+}
+
 #ifdef CONFIG_SERIAL_EARLYCON
 
 int __init early_init_dt_scan_chosen_stdout(void)
@@ -1169,6 +1199,9 @@ void __init early_init_dt_scan_nodes(void)
 
 	/* Handle linux,usable-memory-range property */
 	early_init_dt_check_for_usable_mem_range();
+
+	/* Handle kexec handover */
+	early_init_dt_check_kho();
 }
 
 bool __init early_init_dt_scan(void *dt_virt, phys_addr_t dt_phys)
diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
index 5b924597a4de..db7d7014d8b4 100644
--- a/drivers/of/kexec.c
+++ b/drivers/of/kexec.c
@@ -264,6 +264,38 @@ static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
 }
 #endif /* CONFIG_IMA_KEXEC */
 
+static int kho_add_chosen(const struct kimage *image, void *fdt, int chosen_node)
+{
+	int ret = 0;
+#ifdef CONFIG_KEXEC_HANDOVER
+	phys_addr_t dt_mem = 0;
+	phys_addr_t dt_len = 0;
+	phys_addr_t scratch_mem = 0;
+	phys_addr_t scratch_len = 0;
+
+	if (!image->kho.fdt || !image->kho.scratch)
+		return 0;
+
+	dt_mem = image->kho.fdt->mem;
+	dt_len = image->kho.fdt->memsz;
+
+	scratch_mem = image->kho.scratch->mem;
+	scratch_len = image->kho.scratch->bufsz;
+
+	pr_debug("Adding kho metadata to DT");
+
+	ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, "linux,kho-fdt",
+				       dt_mem, dt_len);
+	if (ret)
+		return ret;
+
+	ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, "linux,kho-scratch",
+				       scratch_mem, scratch_len);
+
+#endif /* CONFIG_KEXEC_HANDOVER */
+	return ret;
+}
+
 /*
  * of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree
  *
@@ -414,6 +446,11 @@ void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
 #endif
 	}
 
+	/* Add kho metadata if this is a KHO image */
+	ret = kho_add_chosen(image, fdt, chosen_node);
+	if (ret)
+		goto out;
+
 	/* add bootargs */
 	if (cmdline) {
 		ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline);
-- 
2.48.1.711.g2feabab25a-goog