arm64: add KHO support

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.

Changes to the "chosen" node have been sent to
https://github.com/devicetree-org/dt-schema/pull/158.

Link: https://lkml.kernel.org/r/20250509074635.3187114-10-changyuanl@google.com
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>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Cc: Ben Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Gowans <jgowans@amazon.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Lendacky <thomas.lendacky@amd.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a182295e6f08bfa0f3e6f630dc4adfe797a4d273..34c79f4fee3f950902b727b85dc6e327a9019c93 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1602,6 +1602,9 @@ 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 aedd0e2dcd890ad2edcb353be4c4df6726a915a1..0edd639898a63fd84cb1303e1e3d5c7fb7351b81 100644 (file)
--- 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 +876,36 @@ 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 fdt_start, fdt_size, 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;
+
+       fdt_start = dt_mem_next_cell(dt_root_addr_cells, &p);
+       fdt_size = 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(fdt_start, fdt_size, scratch_start, scratch_size);
+}
+
 #ifdef CONFIG_SERIAL_EARLYCON
 
 int __init early_init_dt_scan_chosen_stdout(void)
@@ -1169,6 +1200,9 @@ 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 5b924597a4debee76589cf7905ed867422f7dfdc..1ee2d31816aebe6a039346c22e08d754bad06977 100644 (file)
--- a/drivers/of/kexec.c
+++ b/drivers/of/kexec.c
@@ -264,6 +264,43 @@ 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 fdt_mem = 0;
+       phys_addr_t fdt_len = 0;
+       phys_addr_t scratch_mem = 0;
+       phys_addr_t scratch_len = 0;
+
+       ret = fdt_delprop(fdt, chosen_node, "linux,kho-fdt");
+       if (ret && ret != -FDT_ERR_NOTFOUND)
+               return ret;
+       ret = fdt_delprop(fdt, chosen_node, "linux,kho-scratch");
+       if (ret && ret != -FDT_ERR_NOTFOUND)
+               return ret;
+
+       if (!image->kho.fdt || !image->kho.scratch)
+               return 0;
+
+       fdt_mem = image->kho.fdt;
+       fdt_len = PAGE_SIZE;
+       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",
+                                      fdt_mem, fdt_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 +451,11 @@ 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);