On 06/01/21 at 10:53am, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
......
> diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
> index 7850111008a8..b15ebfe40a73 100644
> --- a/arch/x86/platform/efi/quirks.c
> +++ b/arch/x86/platform/efi/quirks.c
> @@ -450,6 +450,18 @@ void __init efi_free_boot_services(void)
> size -= rm_size;
> }
Thanks for taking care of the low-1M excluding in
efi_free_boot_services(), Mike. You might want to remove the old real
mode excluding code either since it's been covered by your new code.
diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index b15ebfe40a73..be814f2089ff 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -409,7 +409,6 @@ void __init efi_free_boot_services(void)
for_each_efi_memory_desc(md) {
unsigned long long start = md->phys_addr;
unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
- size_t rm_size;
if (md->type != EFI_BOOT_SERVICES_CODE &&
md->type != EFI_BOOT_SERVICES_DATA) {
@@ -430,26 +429,6 @@ void __init efi_free_boot_services(void)
*/
efi_unmap_pages(md);
- /*
- * Nasty quirk: if all sub-1MB memory is used for boot
- * services, we can get here without having allocated the
- * real mode trampoline. It's too late to hand boot services
- * memory back to the memblock allocator, so instead
- * try to manually allocate the trampoline if needed.
- *
- * I've seen this on a Dell XPS 13 9350 with firmware
- * 1.4.4 with SGX enabled booting Linux via Fedora 24's
- * grub2-efi on a hard disk. (And no, I don't know why
- * this happened, but Linux should still try to boot rather
- * panicking early.)
- */
- rm_size = real_mode_size_needed();
- if (rm_size && (start + rm_size) < (1<<20) && size >= rm_size) {
- set_real_mode_mem(start);
- start += rm_size;
- size -= rm_size;
- }
-
/*
* Don't free memory under 1M for two reasons:
* - BIOS might clobber it
>
> + /*
> + * Don't free memory under 1M for two reasons:
> + * - BIOS might clobber it
> + * - Crash kernel needs it to be reserved
> + */
> + if (start + size < SZ_1M)
> + continue;
> + if (start < SZ_1M) {
> + size -= (SZ_1M - start);
> + start = SZ_1M;
> + }
> +
> memblock_free_late(start, size);
> }
>
> diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
> index 2e1c1bec0f9e..8ea285aca827 100644
> --- a/arch/x86/realmode/init.c
> +++ b/arch/x86/realmode/init.c
> @@ -29,14 +29,16 @@ void __init reserve_real_mode(void)
>
> /* Has to be under 1M so we can execute real-mode AP code. */
> mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
> - if (!mem) {
> + if (!mem)
> pr_info("No sub-1M memory is available for the trampoline\n");
> - return;
> - }
> + else
> + set_real_mode_mem(mem);
>
> - memblock_reserve(mem, size);
> - set_real_mode_mem(mem);
> - crash_reserve_low_1M();
> + /*
> + * Unconditionally reserve the entire fisrt 1M, see comment in
> + * setup_arch()
> + */
> + memblock_reserve(0, SZ_1M);
> }
>
> static void sme_sev_setup_real_mode(struct trampoline_header *th)
> --
> 2.28.0
>
