On 09/06/2018 02:24 PM, Brijesh Singh wrote:
...
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.
We can use #ifdef CONFIG_AMD_MEM_ENCRYPT around hv_clock_aux definition
so that it gets defined
Something like this:
#ifdef CONFIG_AMD_MEM_ENCRYPT
/* The auxilary array will be used when SEV is active */
#define HVC_AUX_ARRAY_SIZE \
PAGE_ALIGN((NR_CPUS - HVC_BOOT_ARRAY_SIZE) * \
sizeof(struct pvclock_vsyscall_time_info))
static struct pvclock_vsyscall_time_info
hv_clock_aux[HVC_AUX_ARRAY_SIZE] __decrypted_aux;
#endif
