Re: [PATCH v7 19/36] x86/mm: Add support to access boot related data in the clear
From: Matt Fleming
Date: Thu Jun 22 2017 - 07:04:28 EST
On Fri, 16 Jun, at 01:53:26PM, Tom Lendacky wrote:
> Boot data (such as EFI related data) is not encrypted when the system is
> booted because UEFI/BIOS does not run with SME active. In order to access
> this data properly it needs to be mapped decrypted.
> Update early_memremap() to provide an arch specific routine to modify the
> pagetable protection attributes before they are applied to the new
> mapping. This is used to remove the encryption mask for boot related data.
> Update memremap() to provide an arch specific routine to determine if RAM
> remapping is allowed. RAM remapping will cause an encrypted mapping to be
> generated. By preventing RAM remapping, ioremap_cache() will be used
> instead, which will provide a decrypted mapping of the boot related data.
> Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> arch/x86/include/asm/io.h | 5 +
> arch/x86/mm/ioremap.c | 179 +++++++++++++++++++++++++++++++++++++++++++++
> include/linux/io.h | 2 +
> kernel/memremap.c | 20 ++++-
> mm/early_ioremap.c | 18 ++++-
> 5 files changed, 217 insertions(+), 7 deletions(-)
Reviewed-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>