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    Subject[PATCH 5.10 120/146] x86/ioremap: Map EFI-reserved memory as encrypted for SEV
    Date
    From: Tom Lendacky <thomas.lendacky@amd.com>

    commit 8d651ee9c71bb12fc0c8eb2786b66cbe5aa3e43b upstream.

    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@suse.de>
    Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
    Signed-off-by: Joerg Roedel <jroedel@suse.de>
    Signed-off-by: Borislav Petkov <bp@suse.de>
    Tested-by: Joerg Roedel <jroedel@suse.de>
    Cc: <stable@vger.kernel.org> # 5.10+
    Link: https://lkml.kernel.org/r/20210608095439.12668-2-joro@8bytes.org
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/x86/mm/ioremap.c | 4 +++-
    1 file changed, 3 insertions(+), 1 deletion(-)

    --- a/arch/x86/mm/ioremap.c
    +++ b/arch/x86/mm/ioremap.c
    @@ -118,7 +118,9 @@ static void __ioremap_check_other(resour
    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;
    }


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