Messages in this thread | | | Date | Fri, 4 Feb 2022 09:59:45 -0600 | Subject | Re: [PATCH v6 6/6] drivers/node: Show in sysfs node's crypto capabilities | From | Tom Lendacky <> |
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On 2/4/22 07:21, Martin Fernandez wrote: > On 2/4/22, Limonciello, Mario <mario.limonciello@amd.com> wrote: >> On 2/3/2022 10:43, Martin Fernandez wrote: >>> +static ssize_t crypto_capable_show(struct device *dev, >>> + struct device_attribute *attr, char *buf) >>> +{ >>> + struct pglist_data *pgdat = NODE_DATA(dev->id); >>> + >>> + return sysfs_emit(buf, "%d\n", pgdat->crypto_capable); >> >> As there is interest in seeing these capabilities from userspace, it >> seems like a logical time to also expose a `crypto_active` attribute. > > I planned to do something similar to this, but to show (or actually > hide if inactive) tme in cpuinfo, just as Borislav Petkov suggested a > few versions back. > > https://lore.kernel.org/linux-efi/YXrnkxgdjWbcPlJA@zn.tnic/ > >> Then userspace can make a judgement call if the system supports crypto >> memory (`crypto_capable`) and then also whether or not it's been turned >> on (`crypto_active`). >> >> `crypto_active` could be detected with some existing support in the >> kernel of `mem_encrypt_active()`. This will then work for a variety of >> architectures too that offer `mem_encrypt_active()`. > > I need a hand with this, I grepped for mem_encrypt_active and nothing > showed up...
The mem_encrypt_active() function has been replaced by cc_platform_has(CC_ATTR_MEM_ENCRYPT).
> >> As it stands today the only reliable way to tell from userspace (at >> least for AMD's x86 implementation) is by grepping the system log for >> the line "AMD Memory Encryption Features active". > > Isn't enough to grep for sme/sev in cpuinfo?
No, it's not enough. Cpuinfo shows a processors capabilities and not necessarily whether that capability is being used.
Thanks, Tom
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