On Fri, Dec 22, 2023 at 07:35:54PM +0000, Alexander Graf wrote:
> +/**
> + * kho_reserve_previous_mem - Adds all memory reservations into memblocks
> + * and moves us out of the scratch only phase. Must be called after page tables
> + * are initialized and memblock_allow_resize().
> + */
> +void __init kho_reserve_previous_mem(void)
> +{
> + void *mem_virt = __va(mem_phys);
> + int off, err;
> +
> + if (!handover_phys || !mem_phys)
> + return;
> +
> + /*
> + * We reached here because we are running inside a working linear map
> + * that allows us to resize memblocks dynamically. Use the chance and
> + * populate the global fdt pointer
> + */
> + fdt = __va(handover_phys);
> +
> + off = fdt_path_offset(fdt, "/");
> + if (off < 0) {
> + fdt = NULL;
> + return;
> + }
> +
> + err = fdt_node_check_compatible(fdt, off, "kho-v1");
> + if (err) {
> + pr_warn("KHO has invalid compatible, disabling.");
It looks like KHO preserved regions won't be reserved in this case.
Should KHO DT state be destroyed here to prevent KHO memory regions
reuse upon rollback?
> +
> +void __init kho_populate(phys_addr_t handover_dt_phys, phys_addr_t scratch_phys,
> + u64 scratch_len, phys_addr_t mem_cache_phys,
> + u64 mem_cache_len)
> +{
> + void *handover_dt;
> +
> + /* Determine the real size of the DT */
> + handover_dt = early_memremap(handover_dt_phys, sizeof(struct fdt_header));
> + if (!handover_dt) {
> + pr_warn("setup: failed to memremap kexec FDT (0x%llx)\n", handover_dt_phys);
> + return;
> + }
> +
> + if (fdt_check_header(handover_dt)) {
> + pr_warn("setup: kexec handover FDT is invalid (0x%llx)\n", handover_dt_phys);
> + early_memunmap(handover_dt, PAGE_SIZE);
> + return;
> + }
> +
> + handover_len = fdt_totalsize(handover_dt);
> + handover_phys = handover_dt_phys;
> +
> + /* Reserve the DT so we can still access it in late boot */
> + memblock_reserve(handover_phys, handover_len);
> +
> + /* Reserve the mem cache so we can still access it later */
> + memblock_reserve(mem_cache_phys, mem_cache_len);
> +
> + /*
> + * We pass a safe contiguous block of memory to use for early boot purporses from
> + * the previous kernel so that we can resize the memblock array as needed.
> + */
> + memblock_add(scratch_phys, scratch_len);
> +
> + if (WARN_ON(memblock_mark_scratch(scratch_phys, scratch_len))) {
> + pr_err("Kexec failed to mark the scratch region. Disabling KHO.");
> + handover_len = 0;
> + handover_phys = 0;
Same question here: doesn't all the KHO state gets invalid in case of any
restoration error?
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