The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 1ff2fc02862d52e18fd3daabcfe840ec27e920a8 Mon Sep 17 00:00:00 2001
From: Tom Lendacky thomas.lendacky@amd.com Date: Wed, 20 Oct 2021 13:02:11 -0500 Subject: [PATCH] x86/sme: Explicitly map new EFI memmap table as encrypted
Reserving memory using efi_mem_reserve() calls into the x86 efi_arch_mem_reserve() function. This function will insert a new EFI memory descriptor into the EFI memory map representing the area of memory to be reserved and marking it as EFI runtime memory. As part of adding this new entry, a new EFI memory map is allocated and mapped. The mapping is where a problem can occur. This new memory map is mapped using early_memremap() and generally mapped encrypted, unless the new memory for the mapping happens to come from an area of memory that is marked as EFI_BOOT_SERVICES_DATA memory. In this case, the new memory will be mapped unencrypted. However, during replacement of the old memory map, efi_mem_type() is disabled, so the new memory map will now be long-term mapped encrypted (in efi.memmap), resulting in the map containing invalid data and causing the kernel boot to crash.
Since it is known that the area will be mapped encrypted going forward, explicitly map the new memory map as encrypted using early_memremap_prot().
Cc: stable@vger.kernel.org # 4.14.x Fixes: 8f716c9b5feb ("x86/mm: Add support to access boot related data in the clear") Link: https://lore.kernel.org/all/ebf1eb2940405438a09d51d121ec0d02c8755558.1634752... Signed-off-by: Tom Lendacky thomas.lendacky@amd.com [ardb: incorporate Kconfig fix by Arnd] Signed-off-by: Ard Biesheuvel ardb@kernel.org
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 95dd1ee01546..9636a3122496 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1932,6 +1932,7 @@ config EFI depends on ACPI select UCS2_STRING select EFI_RUNTIME_WRAPPERS + select ARCH_USE_MEMREMAP_PROT help This enables the kernel to use EFI runtime services that are available (such as the EFI variable services). diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c index b15ebfe40a73..b0b848d6933a 100644 --- a/arch/x86/platform/efi/quirks.c +++ b/arch/x86/platform/efi/quirks.c @@ -277,7 +277,8 @@ void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size) return; }
- new = early_memremap(data.phys_map, data.size); + new = early_memremap_prot(data.phys_map, data.size, + pgprot_val(pgprot_encrypted(FIXMAP_PAGE_NORMAL))); if (!new) { pr_err("Failed to map new boot services memmap\n"); return;