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SubjectRe: [PATCH v6 14/34] x86/mm: Insure that boot memory areas are mapped properly
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On 6/10/2017 11:01 AM, Borislav Petkov wrote:
> On Wed, Jun 07, 2017 at 02:15:39PM -0500, Tom Lendacky wrote:
>> The boot data and command line data are present in memory in a decrypted
>> state and are copied early in the boot process. The early page fault
>> support will map these areas as encrypted, so before attempting to copy
>> them, add decrypted mappings so the data is accessed properly when copied.
>>
>> For the initrd, encrypt this data in place. Since the future mapping of the
>> initrd area will be mapped as encrypted the data will be accessed properly.
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
>> ---
>> arch/x86/include/asm/mem_encrypt.h | 11 +++++
>> arch/x86/include/asm/pgtable.h | 3 +
>> arch/x86/kernel/head64.c | 30 ++++++++++++--
>> arch/x86/kernel/setup.c | 9 ++++
>> arch/x86/mm/mem_encrypt.c | 77 ++++++++++++++++++++++++++++++++++++
>> 5 files changed, 126 insertions(+), 4 deletions(-)
>
> Some cleanups ontop in case you get to send v7:

There will be a v7.

>
> diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
> index 61a704945294..5959a42dd4d5 100644
> --- a/arch/x86/include/asm/mem_encrypt.h
> +++ b/arch/x86/include/asm/mem_encrypt.h
> @@ -45,13 +45,8 @@ static inline void __init sme_early_decrypt(resource_size_t paddr,
> {
> }
>
> -static inline void __init sme_map_bootdata(char *real_mode_data)
> -{
> -}
> -
> -static inline void __init sme_unmap_bootdata(char *real_mode_data)
> -{
> -}
> +static inline void __init sme_map_bootdata(char *real_mode_data) { }
> +static inline void __init sme_unmap_bootdata(char *real_mode_data) { }
>
> static inline void __init sme_early_init(void)
> {
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index 2321f05045e5..32ebbe0ab04d 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -132,6 +132,10 @@ static void __init __sme_map_unmap_bootdata(char *real_mode_data, bool map)
> struct boot_params *boot_data;
> unsigned long cmdline_paddr;
>
> + /* If SME is not active, the bootdata is in the correct state */
> + if (!sme_active())
> + return;
> +
> __sme_early_map_unmap_mem(real_mode_data, sizeof(boot_params), map);
> boot_data = (struct boot_params *)real_mode_data;
>
> @@ -142,40 +146,22 @@ static void __init __sme_map_unmap_bootdata(char *real_mode_data, bool map)
> cmdline_paddr = boot_data->hdr.cmd_line_ptr |
> ((u64)boot_data->ext_cmd_line_ptr << 32);
>
> - if (cmdline_paddr)
> - __sme_early_map_unmap_mem(__va(cmdline_paddr),
> - COMMAND_LINE_SIZE, map);
> + if (!cmdline_paddr)
> + return;
> +
> + __sme_early_map_unmap_mem(__va(cmdline_paddr), COMMAND_LINE_SIZE, map);
> +
> + sme_early_pgtable_flush();

Yup, overall it definitely simplifies things.

I have to call sme_early_pgtable_flush() even if cmdline_paddr is NULL,
so I'll either keep the if and have one flush at the end or I can move
the flush into __sme_early_map_unmap_mem(). I'm leaning towards the
latter.

Thanks,
Tom

> }
>
> void __init sme_unmap_bootdata(char *real_mode_data)
> {
> - /* If SME is not active, the bootdata is in the correct state */
> - if (!sme_active())
> - return;
> -
> - /*
> - * The bootdata and command line aren't needed anymore so clear
> - * any mapping of them.
> - */
> __sme_map_unmap_bootdata(real_mode_data, false);
> -
> - sme_early_pgtable_flush();
> }
>
> void __init sme_map_bootdata(char *real_mode_data)
> {
> - /* If SME is not active, the bootdata is in the correct state */
> - if (!sme_active())
> - return;
> -
> - /*
> - * The bootdata and command line will not be encrypted, so they
> - * need to be mapped as decrypted memory so they can be copied
> - * properly.
> - */
> __sme_map_unmap_bootdata(real_mode_data, true);
> -
> - sme_early_pgtable_flush();
> }
>
> void __init sme_early_init(void)
>

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