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SubjectRe: [PATCH 2/3 v3] x86/kexec: Set the C-bit in the identity map page table when SEV is active
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在 2019年05月15日 21:30, Borislav Petkov 写道:
> On Tue, Apr 30, 2019 at 03:44:20PM +0800, Lianbo Jiang wrote:
>> When SEV is active, the second kernel image is loaded into the
>> encrypted memory. Lets make sure that when kexec builds the
>> identity mapping page table it adds the memory encryption mask(C-bit).
>>
>> Co-developed-by: Brijesh Singh <brijesh.singh@amd.com>
>> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
>> Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
>> ---
>> arch/x86/kernel/machine_kexec_64.c | 12 +++++++++++-
>> 1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
>> index f60611531d17..11fe352f7344 100644
>> --- a/arch/x86/kernel/machine_kexec_64.c
>> +++ b/arch/x86/kernel/machine_kexec_64.c
>> @@ -56,6 +56,7 @@ static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
>> pte_t *pte;
>> unsigned long vaddr, paddr;
>> int result = -ENOMEM;
>> + pgprot_t prot = PAGE_KERNEL_EXEC_NOENC;
>>
>> vaddr = (unsigned long)relocate_kernel;
>> paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
>> @@ -92,7 +93,11 @@ static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
>> set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
>> }
>> pte = pte_offset_kernel(pmd, vaddr);
>> - set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC_NOENC));
>> +
>> + if (sev_active())
>> + prot = PAGE_KERNEL_EXEC;
>> +
>> + set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
>> return 0;
>> err:
>> return result;
>> @@ -129,6 +134,11 @@ static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
>> level4p = (pgd_t *)__va(start_pgtable);
>> clear_page(level4p);
>>
>> + if (sev_active()) {
>> + info.page_flag |= _PAGE_ENC;
>> + info.kernpg_flag = _KERNPG_TABLE;
>
> kernpg_flag above is initialized to _KERNPG_TABLE_NOENC so you can do here
>
> info.kernpg_flag |= _PAGE_ENC;
>
> too, to make it even more clear what this does, right?
>
OK, i will modify it according to your suggestion and post again.

Thanks.
Lianbo

> IOW:
>
> diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
> index 783ce5184405..16c37fe489bc 100644
> --- a/arch/x86/kernel/machine_kexec_64.c
> +++ b/arch/x86/kernel/machine_kexec_64.c
> @@ -135,8 +135,8 @@ static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
> clear_page(level4p);
>
> if (sev_active()) {
> - info.page_flag |= _PAGE_ENC;
> - info.kernpg_flag = _KERNPG_TABLE;
> + info.page_flag |= _PAGE_ENC;
> + info.kernpg_flag |= _PAGE_ENC;
> }
>
> if (direct_gbpages)
>
>

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