On Tue, Nov 29, 2016 at 12:48:17PM -0600, Tom Lendacky wrote: > > One more thing: just like we're adding an =on switch, we'd need an =off > > switch in case something's wrong with the SME code. IOW, if a user > > supplies "mem_encrypt=off", we do not encrypt. > > Well, we can document "off", but if the exact string "mem_encrypt=on" > isn't specified on the command line then the encryption won't occur. So you have this: + /* + * Fixups have not been to applied phys_base yet, so we must obtain + * the address to the SME command line option in the following way. + */ + asm ("lea sme_cmdline_arg(%%rip), %0" + : "=r" (cmdline_arg) + : "p" (sme_cmdline_arg)); + cmdline_ptr = bp->hdr.cmd_line_ptr | ((u64)bp->ext_cmd_line_ptr << 32); + if (cmdline_find_option_bool((char *)cmdline_ptr, cmdline_arg)) + sme_me_mask = 1UL << (ebx & 0x3f); If I parse this right, we will enable SME *only* if mem_encrypt=on is explicitly supplied on the command line. Which means, users will have to *know* about that cmdline switch first. Which then means, we have to go and tell them. Do you see where I'm going with this? I know we talked about this already but I still think we should enable it by default and people who don't want it will use the =off switch. We can also do something like CONFIG_AMD_SME_ENABLED_BY_DEFAULT which we can be selected during build for the different setups. Hmmm. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>