From 1debf0958fa27b7c469dbf22754929ec59a7c0e7 Mon Sep 17 00:00:00 2001 From: Sai Praneeth Prakhya Date: Fri, 21 Dec 2018 18:22:34 -0800 Subject: [PATCH] x86/efi: Don't unmap EFI boot services code/data regions for EFI_OLD_MEMMAP and EFI_MIXED_MODE The following commit: d5052a7130a6 ("x86/efi: Unmap EFI boot services code/data regions from efi_pgd") forgets to take two EFI modes into consideration, namely EFI_OLD_MEMMAP and EFI_MIXED_MODE: - EFI_OLD_MEMMAP is a legacy way of mapping EFI regions into swapper_pg_dir using ioremap() and init_memory_mapping(). This feature can be enabled by passing "efi=old_map" as kernel command line argument. But, efi_unmap_pages() unmaps EFI boot services code/data regions *only* from efi_pgd and hence cannot be used for unmapping EFI boot services code/data regions from swapper_pg_dir. Introduce a temporary fix to not unmap EFI boot services code/data regions when EFI_OLD_MEMMAP is enabled while working on a real fix. - EFI_MIXED_MODE is another feature where a 64-bit kernel runs on a 64-bit platform crippled by a 32-bit firmware. To support EFI_MIXED_MODE, all RAM (i.e. namely EFI regions like EFI_CONVENTIONAL_MEMORY, EFI_LOADER_, EFI_BOOT_SERVICES_ and EFI_RUNTIME_CODE/DATA regions) is mapped into efi_pgd all the time to facilitate EFI runtime calls access it's arguments in 1:1 mode. Hence, don't unmap EFI boot services code/data regions when booted in mixed mode. Signed-off-by: Sai Praneeth Prakhya Acked-by: Ard Biesheuvel Cc: Andy Lutomirski Cc: Bhupesh Sharma Cc: Borislav Petkov Cc: Dave Hansen Cc: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20181222022234.7573-1-sai.praneeth.prakhya@intel.com Signed-off-by: Ingo Molnar --- arch/x86/platform/efi/quirks.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c index 09e811b9da26..17456a1d3f04 100644 --- a/arch/x86/platform/efi/quirks.c +++ b/arch/x86/platform/efi/quirks.c @@ -380,6 +380,22 @@ static void __init efi_unmap_pages(efi_memory_desc_t *md) u64 pa = md->phys_addr; u64 va = md->virt_addr; + /* + * To Do: Remove this check after adding functionality to unmap EFI boot + * services code/data regions from direct mapping area because + * "efi=old_map" maps EFI regions in swapper_pg_dir. + */ + if (efi_enabled(EFI_OLD_MEMMAP)) + return; + + /* + * EFI mixed mode has all RAM mapped to access arguments while making + * EFI runtime calls, hence don't unmap EFI boot services code/data + * regions. + */ + if (!efi_is_native()) + return; + if (kernel_unmap_pages_in_pgd(pgd, pa, md->num_pages)) pr_err("Failed to unmap 1:1 mapping for 0x%llx\n", pa); -- 2.39.5