From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A4DBD3234 for ; Fri, 2 May 2025 00:43:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746146614; cv=none; b=lwg6vkc0ukiH++4bVfdJjSbqKT0OFI5PhTOz7+icKoj7uk07vbf3eTaWc9jWVfmoYhjB2dcWQ6+8cGqOrI7E9yC4oNxHbQ/bFw2vyWXeRn0uCqLJc32UwfMGLnuBweA2R8+hvoS8QWtLbJhsM86BksUpKGDQPDK0xaFqOZXI8QE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746146614; c=relaxed/simple; bh=NurfGJWlo4h++4aePjK/sjDKsK+G+ZinPMyOUsI3sNQ=; h=Date:To:From:Subject:Message-Id; b=mDo54pBmfmL2Qp5i7nB9SmsBAvWtYGhx8J9hnU6WYmZQJhD1/+qtUAtpMme64KO1+kHJteEKvCTG+en0UNnz8idMgE0XV1OR9KtTAxBuU4pzzTuDBKNmbNUbZpxOjhP1p+Fo33M2VV0whdOaGdu2pnKq8DIuNSV98KC6D8jSCP4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=gg90rjkN; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="gg90rjkN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6CB21C4CEE3; Fri, 2 May 2025 00:43:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1746146614; bh=NurfGJWlo4h++4aePjK/sjDKsK+G+ZinPMyOUsI3sNQ=; h=Date:To:From:Subject:From; b=gg90rjkNB8MH1hWux5zpaP+9Bsq/pH/iw3IH2oQmRIyGKzvVTKSNvMiJ7tBlMPcn7 5bEbRxdkmohMbvB8Px9DniN3EzUPDA6/l4vc94no5XI279MOEwRUDQ/Ga8a1XMSl6i PDtV0gSRTUS0b4+jhIIfyWylqp6McFZ1iPXlQx8A= Date: Thu, 01 May 2025 17:43:33 -0700 To: mm-commits@vger.kernel.org,rppt@kernel.org,changyuanl@google.com,graf@amazon.com,akpm@linux-foundation.org From: Andrew Morton Subject: + kexec-add-kho-support-to-kexec-file-loads.patch added to mm-unstable branch Message-Id: <20250502004334.6CB21C4CEE3@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: kexec: add KHO support to kexec file loads has been added to the -mm mm-unstable branch. Its filename is kexec-add-kho-support-to-kexec-file-loads.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kexec-add-kho-support-to-kexec-file-loads.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Alexander Graf Subject: kexec: add KHO support to kexec file loads Date: Thu, 1 May 2025 15:54:15 -0700 Kexec has 2 modes: A user space driven mode and a kernel driven mode. For the kernel driven mode, kernel code determines the physical addresses of all target buffers that the payload gets copied into. With KHO, we can only safely copy payloads into the "scratch area". Teach the kexec file loader about it, so it only allocates for that area. In addition, enlighten it with support to ask the KHO subsystem for its respective payloads to copy into target memory. Also teach the KHO subsystem how to fill the images for file loads. Link: https://lkml.kernel.org/r/20250501225425.635167-9-changyuanl@google.com Signed-off-by: Alexander Graf Co-developed-by: Mike Rapoport (Microsoft) Signed-off-by: Mike Rapoport (Microsoft) Co-developed-by: Changyuan Lyu Signed-off-by: Changyuan Lyu Signed-off-by: Andrew Morton --- include/linux/kexec.h | 5 ++ kernel/kexec_file.c | 13 +++++++ kernel/kexec_handover.c | 67 ++++++++++++++++++++++++++++++++++++++ kernel/kexec_internal.h | 16 +++++++++ 4 files changed, 101 insertions(+) --- a/include/linux/kexec.h~kexec-add-kho-support-to-kexec-file-loads +++ a/include/linux/kexec.h @@ -371,6 +371,11 @@ struct kimage { size_t ima_buffer_size; #endif + struct { + struct kexec_segment *scratch; + phys_addr_t fdt; + } kho; + /* Core ELF header buffer */ void *elf_headers; unsigned long elf_headers_sz; --- a/kernel/kexec_file.c~kexec-add-kho-support-to-kexec-file-loads +++ a/kernel/kexec_file.c @@ -253,6 +253,11 @@ kimage_file_prepare_segments(struct kima /* IMA needs to pass the measurement list to the next kernel. */ ima_add_kexec_buffer(image); + /* If KHO is active, add its images to the list */ + ret = kho_fill_kimage(image); + if (ret) + goto out; + /* Call image load handler */ ldata = kexec_image_load_default(image); @@ -648,6 +653,14 @@ int kexec_locate_mem_hole(struct kexec_b if (kbuf->mem != KEXEC_BUF_MEM_UNKNOWN) return 0; + /* + * If KHO is active, only use KHO scratch memory. All other memory + * could potentially be handed over. + */ + ret = kho_locate_mem_hole(kbuf, locate_mem_hole_callback); + if (ret <= 0) + return ret; + if (!IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) ret = kexec_walk_resources(kbuf, locate_mem_hole_callback); else --- a/kernel/kexec_handover.c~kexec-add-kho-support-to-kexec-file-loads +++ a/kernel/kexec_handover.c @@ -26,6 +26,7 @@ * internal APIs. */ #include "../mm/internal.h" +#include "kexec_internal.h" #define KHO_FDT_COMPATIBLE "kho-v1" #define PROP_PRESERVED_MEMORY_MAP "preserved-memory-map" @@ -1192,3 +1193,69 @@ out: if (err) pr_warn("disabling KHO revival: %d\n", err); } + +/* Helper functions for kexec_file_load */ + +int kho_fill_kimage(struct kimage *image) +{ + ssize_t scratch_size; + int err = 0; + struct kexec_buf scratch; + + if (!kho_enable) + return 0; + + image->kho.fdt = page_to_phys(kho_out.ser.fdt); + + scratch_size = sizeof(*kho_scratch) * kho_scratch_cnt; + scratch = (struct kexec_buf){ + .image = image, + .buffer = kho_scratch, + .bufsz = scratch_size, + .mem = KEXEC_BUF_MEM_UNKNOWN, + .memsz = scratch_size, + .buf_align = SZ_64K, /* Makes it easier to map */ + .buf_max = ULONG_MAX, + .top_down = true, + }; + err = kexec_add_buffer(&scratch); + if (err) + return err; + image->kho.scratch = &image->segment[image->nr_segments - 1]; + + return 0; +} + +static int kho_walk_scratch(struct kexec_buf *kbuf, + int (*func)(struct resource *, void *)) +{ + int ret = 0; + int i; + + for (i = 0; i < kho_scratch_cnt; i++) { + struct resource res = { + .start = kho_scratch[i].addr, + .end = kho_scratch[i].addr + kho_scratch[i].size - 1, + }; + + /* Try to fit the kimage into our KHO scratch region */ + ret = func(&res, kbuf); + if (ret) + break; + } + + return ret; +} + +int kho_locate_mem_hole(struct kexec_buf *kbuf, + int (*func)(struct resource *, void *)) +{ + int ret; + + if (!kho_enable || kbuf->image->type == KEXEC_TYPE_CRASH) + return 1; + + ret = kho_walk_scratch(kbuf, func); + + return ret == 1 ? 0 : -EADDRNOTAVAIL; +} --- a/kernel/kexec_internal.h~kexec-add-kho-support-to-kexec-file-loads +++ a/kernel/kexec_internal.h @@ -39,4 +39,20 @@ extern size_t kexec_purgatory_size; #else /* CONFIG_KEXEC_FILE */ static inline void kimage_file_post_load_cleanup(struct kimage *image) { } #endif /* CONFIG_KEXEC_FILE */ + +struct kexec_buf; + +#ifdef CONFIG_KEXEC_HANDOVER +int kho_locate_mem_hole(struct kexec_buf *kbuf, + int (*func)(struct resource *, void *)); +int kho_fill_kimage(struct kimage *image); +#else +static inline int kho_locate_mem_hole(struct kexec_buf *kbuf, + int (*func)(struct resource *, void *)) +{ + return 1; +} + +static inline int kho_fill_kimage(struct kimage *image) { return 0; } +#endif /* CONFIG_KEXEC_HANDOVER */ #endif /* LINUX_KEXEC_INTERNAL_H */ _ Patches currently in -mm which might be from graf@amazon.com are memblock-add-support-for-scratch-memory.patch kexec-add-kexec-handover-kho-generation-helpers.patch kexec-add-kho-parsing-support.patch kexec-add-kho-support-to-kexec-file-loads.patch kexec-add-config-option-for-kho.patch arm64-add-kho-support.patch x86-kexec-add-support-for-passing-kexec-handover-kho-data.patch x86-e820-temporarily-enable-kho-scratch-for-memory-below-1m.patch x86-boot-make-sure-kaslr-does-not-step-over-kho-preserved-memory.patch x86-kconfig-enable-kexec-handover-for-64-bits.patch memblock-add-kho-support-for-reserve_mem.patch documentation-add-documentation-for-kho.patch