On 09/06/2018 01:47 PM, Sean Christopherson wrote:
On Thu, Sep 06, 2018 at 01:37:50PM -0500, Brijesh Singh wrote:
On 09/06/2018 09:18 AM, Sean Christopherson wrote:
....
So are we going to be defining a decrypted section for every piece of
machinery now?
That's a bit too much in my book.
Why can't you simply free everything in .data..decrypted on !SVE guests?
That would prevent adding __decrypted to existing declarations, e.g.
hv_clock_boot, which would be ugly in its own right. A more generic
solution would be to add something like __decrypted_exclusive to mark
data that is used if and only if SEV is active, and then free the
SEV-only data when SEV is disabled.
Oh, and we'd need to make sure __decrypted_exclusive is freed when
!CONFIG_AMD_MEM_ENCRYPT, and preferably !sev_active() since the big
array is used only if SEV is active. This patch unconditionally
defines hv_clock_dec but only frees it if CONFIG_AMD_MEM_ENCRYPT=y &&
!mem_encrypt_active().
Again we have to consider the bare metal scenario while doing this. The
aux array you proposed will be added in decrypted section only when
CONFIG_AMD_MEM_ENCRYPT=y. If CONFIG_AMD_MEM_ENCRYPT=n then nothng
gets put in .data.decrypted section. At the runtime, if memory
encryption is active then .data.decrypted_hvclock will contains useful
data.
The __decrypted attribute in "" when CONFIG_AMD_MEM_ENCRYPT=n.
Right, but won't the data get dumped into the regular .bss in that
case, i.e. needs to be freed?
Yes, the auxiliary array will dumped into the regular .bss when
CONFIG_AMD_MEM_ENCRYPT=n. Typically it will be few k, I am not
sure if its worth complicating the code to save those extra memory.
Most of the distro's have CONFIG_AMD_MEM_ENCRYPT=y anyways.
