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SubjectRe: [RFC PATCH v3 10/20] Add support to access boot related data in the clear
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On 11/11/2016 10:17 AM, Kani, Toshimitsu wrote:
> On Wed, 2016-11-09 at 18:36 -0600, Tom Lendacky wrote:
>> Boot data (such as EFI related data) is not encrypted when the system
>> is booted and needs to be accessed unencrypted. Add support to apply
>> the proper attributes to the EFI page tables and to the
>> early_memremap and memremap APIs to identify the type of data being
>> accessed so that the proper encryption attribute can be applied.
> :
>> +static bool memremap_apply_encryption(resource_size_t phys_addr,
>> + unsigned long size)
>> +{
>> + /* SME is not active, just return true */
>> + if (!sme_me_mask)
>> + return true;
>> +
>> + /* Check if the address is part of the setup data */
>> + if (memremap_setup_data(phys_addr, size))
>> + return false;
>> +
>> + /* Check if the address is part of EFI boot/runtime data */
>> + switch (efi_mem_type(phys_addr)) {
>> + case EFI_BOOT_SERVICES_DATA:
>> + case EFI_RUNTIME_SERVICES_DATA:
>> + return false;
>> + }
>> +
>> + /* Check if the address is outside kernel usable area */
>> + switch (e820_get_entry_type(phys_addr, phys_addr + size -
>> 1)) {
>> + case E820_RESERVED:
>> + case E820_ACPI:
>> + case E820_NVS:
>> + case E820_UNUSABLE:
>> + return false;
>> + }
>> +
>> + return true;
>> +}
>
> Are you supporting encryption for E820_PMEM ranges? If so, this
> encryption will persist across a reboot and does not need to be
> encrypted again, right? Also, how do you keep a same key across a
> reboot?

The key will change across a reboot... so I need to look into this
more for memory that isn't used as traditional system ram.

Thanks,
Tom

>
> Thanks,
> -Toshi
>

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