Hi Jarkko,
On 5/11/2022 3:43 AM, Jarkko Sakkinen wrote:
> On Mon, May 09, 2022 at 02:48:00PM -0700, Reinette Chatre wrote:
>> Recent commit 08999b2489b4 ("x86/sgx: Free backing memory
>> after faulting the enclave page") expanded __sgx_encl_eldu()
>> to clear an enclave page's PCMD (Paging Crypto MetaData)
>> from the PCMD page in the backing store after the enclave
>> page is restored to the enclave.
>>
>> Since the PCMD page in the backing store is modified the page
>> should be marked as dirty to ensure the modified data is retained.
>>
>> Fixes: 08999b2489b4 ("x86/sgx: Free backing memory after faulting the enclave page")
>> Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
>> ---
>> Changes since RFC v1:
>> - Do not set dirty bit on enclave page since it is not being
>> written to and always will be discarded. (Dave)
>>
>> arch/x86/kernel/cpu/sgx/encl.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
>> index 398695a20605..2521d64e8bcf 100644
>> --- a/arch/x86/kernel/cpu/sgx/encl.c
>> +++ b/arch/x86/kernel/cpu/sgx/encl.c
>> @@ -83,6 +83,7 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page,
>> ret = -EFAULT;
>> }
>>
>> + set_page_dirty(b.pcmd);
>> memset(pcmd_page + b.pcmd_offset, 0, sizeof(struct sgx_pcmd));
>>
>> /*
>> --
>> 2.25.1
>>
>
> LGTM.
>
> Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
Thank you very much.
Based on my understanding of Dave's feedback I do plan to move the
set_page_dirty() to be after the memset:
https://lore.kernel.org/linux-sgx/8922e48f-6646-c7cc-6393-7c78dcf23d23@xxxxxxxxx/
Reinette
