ACK: [SRU][Hirsute][PATCH 1/1] x86/ioremap: Map EFI-reserved memory as encrypted for SEV

[Tim Gardner]

Acked-by: Tim Gardner <tim.gardner at canonical.com>

On 7/7/21 11:57 PM, Khalid Elmously wrote:
> From: Tom Lendacky <thomas.lendacky at amd.com>
> 
> BugLink: https://bugs.launchpad.com/bugs/1931254
> 
> Some drivers require memory that is marked as EFI boot services
> data. In order for this memory to not be re-used by the kernel
> after ExitBootServices(), efi_mem_reserve() is used to preserve it
> by inserting a new EFI memory descriptor and marking it with the
> EFI_MEMORY_RUNTIME attribute.
> 
> Under SEV, memory marked with the EFI_MEMORY_RUNTIME attribute needs to
> be mapped encrypted by Linux, otherwise the kernel might crash at boot
> like below:
> 
>    EFI Variables Facility v0.08 2004-May-17
>    general protection fault, probably for non-canonical address 0x3597688770a868b2: 0000 [#1] SMP NOPTI
>    CPU: 13 PID: 1 Comm: swapper/0 Not tainted 5.12.4-2-default #1 openSUSE Tumbleweed
>    Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>    RIP: 0010:efi_mokvar_entry_next
>    [...]
>    Call Trace:
>     efi_mokvar_sysfs_init
>     ? efi_mokvar_table_init
>     do_one_initcall
>     ? __kmalloc
>     kernel_init_freeable
>     ? rest_init
>     kernel_init
>     ret_from_fork
> 
> Expand the __ioremap_check_other() function to additionally check for
> this other type of boot data reserved at runtime and indicate that it
> should be mapped encrypted for an SEV guest.
> 
>   [ bp: Massage commit message. ]
> 
> Fixes: 58c909022a5a ("efi: Support for MOK variable config table")
> Reported-by: Joerg Roedel <jroedel at suse.de>
> Signed-off-by: Tom Lendacky <thomas.lendacky at amd.com>
> Signed-off-by: Joerg Roedel <jroedel at suse.de>
> Signed-off-by: Borislav Petkov <bp at suse.de>
> Tested-by: Joerg Roedel <jroedel at suse.de>
> Cc: <stable at vger.kernel.org> # 5.10+
> Link: https://lkml.kernel.org/r/20210608095439.12668-2-joro@8bytes.org
> (cherry picked from commit 8d651ee9c71bb12fc0c8eb2786b66cbe5aa3e43b)
> Signed-off-by: Khalid Elmously <khalid.elmously at canonical.com>
> ---
>   arch/x86/mm/ioremap.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index 9e5ccc56f8e0..356b746dfbe7 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -118,7 +118,9 @@ static void __ioremap_check_other(resource_size_t addr, struct ioremap_desc *des
>   	if (!IS_ENABLED(CONFIG_EFI))
>   		return;
>   
> -	if (efi_mem_type(addr) == EFI_RUNTIME_SERVICES_DATA)
> +	if (efi_mem_type(addr) == EFI_RUNTIME_SERVICES_DATA ||
> +	    (efi_mem_type(addr) == EFI_BOOT_SERVICES_DATA &&
> +	     efi_mem_attributes(addr) & EFI_MEMORY_RUNTIME))
>   		desc->flags |= IORES_MAP_ENCRYPTED;
>   }
>   
> 

-- 
-----------
Tim Gardner
Canonical, Inc