diff options
| -rw-r--r-- | arch/x86/kernel/setup.c | 35 | ||||
| -rw-r--r-- | arch/x86/platform/efi/quirks.c | 12 | ||||
| -rw-r--r-- | arch/x86/realmode/init.c | 14 |
3 files changed, 41 insertions, 20 deletions
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index ff653d608d5f..1e720626069a 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -638,11 +638,11 @@ static void __init trim_snb_memory(void) * them from accessing certain memory ranges, namely anything below * 1M and in the pages listed in bad_pages[] above. * - * To avoid these pages being ever accessed by SNB gfx devices - * reserve all memory below the 1 MB mark and bad_pages that have - * not already been reserved at boot time. + * To avoid these pages being ever accessed by SNB gfx devices reserve + * bad_pages that have not already been reserved at boot time. + * All memory below the 1 MB mark is anyway reserved later during + * setup_arch(), so there is no need to reserve it here. */ - memblock_reserve(0, 1<<20); for (i = 0; i < ARRAY_SIZE(bad_pages); i++) { if (memblock_reserve(bad_pages[i], PAGE_SIZE)) @@ -734,14 +734,14 @@ static void __init early_reserve_memory(void) * The first 4Kb of memory is a BIOS owned area, but generally it is * not listed as such in the E820 table. * - * Reserve the first memory page and typically some additional - * memory (64KiB by default) since some BIOSes are known to corrupt - * low memory. See the Kconfig help text for X86_RESERVE_LOW. + * Reserve the first 64K of memory since some BIOSes are known to + * corrupt low memory. After the real mode trampoline is allocated the + * rest of the memory below 640k is reserved. * * In addition, make sure page 0 is always reserved because on * systems with L1TF its contents can be leaked to user processes. */ - memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE)); + memblock_reserve(0, SZ_64K); early_reserve_initrd(); @@ -752,6 +752,7 @@ static void __init early_reserve_memory(void) reserve_ibft_region(); reserve_bios_regions(); + trim_snb_memory(); } /* @@ -1082,14 +1083,20 @@ void __init setup_arch(char **cmdline_p) (max_pfn_mapped<<PAGE_SHIFT) - 1); #endif - reserve_real_mode(); - /* - * Reserving memory causing GPU hangs on Sandy Bridge integrated - * graphics devices should be done after we allocated memory under - * 1M for the real mode trampoline. + * Find free memory for the real mode trampoline and place it + * there. + * If there is not enough free memory under 1M, on EFI-enabled + * systems there will be additional attempt to reclaim the memory + * for the real mode trampoline at efi_free_boot_services(). + * + * Unconditionally reserve the entire first 1M of RAM because + * BIOSes are know to corrupt low memory and several + * hundred kilobytes are not worth complex detection what memory gets + * clobbered. Moreover, on machines with SandyBridge graphics or in + * setups that use crashkernel the entire 1M is reserved anyway. */ - trim_snb_memory(); + reserve_real_mode(); init_mem_mapping(); 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; } + /* + * 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..6534c92d0f83 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) |