On Fri, 2019-11-29 at 18:02 +0800, Lars Persson wrote:
> Hi Neal,
>
> On Wed, Nov 27, 2019 at 3:23 PM Neal Liu <[email protected]> wrote:
> >
> > For MediaTek SoCs on ARMv8 with TrustZone enabled, peripherals like
> > entropy sources is not accessible from normal world (linux) and
> > rather accessible from secure world (ATF/TEE) only. This driver aims
> > to provide a generic interface to ATF rng service.
> >
>
> I am working on several SoCs that also will need this kind of driver
> to get entropy from Arm trusted firmware.
> If you intend to make this a generic interface, please clean up the
> references to MediaTek and give it a more generic name. For example
> "Arm Trusted Firmware random number driver".
>
> It will also be helpful if the SMC call number is configurable.
>
> - Lars
Yes, I'm trying to make this to a generic interface. I'll try to make
HW/platform related dependency to be configurable and let it more
generic.
Thanks for your suggestion.
>
> _______________________________________________
> Linux-mediatek mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-mediatek
(adding some more arm64 folks)
On Fri, 29 Nov 2019 at 11:30, Neal Liu <[email protected]> wrote:
>
> On Fri, 2019-11-29 at 18:02 +0800, Lars Persson wrote:
> > Hi Neal,
> >
> > On Wed, Nov 27, 2019 at 3:23 PM Neal Liu <[email protected]> wrote:
> > >
> > > For MediaTek SoCs on ARMv8 with TrustZone enabled, peripherals like
> > > entropy sources is not accessible from normal world (linux) and
> > > rather accessible from secure world (ATF/TEE) only. This driver aims
> > > to provide a generic interface to ATF rng service.
> > >
> >
> > I am working on several SoCs that also will need this kind of driver
> > to get entropy from Arm trusted firmware.
> > If you intend to make this a generic interface, please clean up the
> > references to MediaTek and give it a more generic name. For example
> > "Arm Trusted Firmware random number driver".
> >
> > It will also be helpful if the SMC call number is configurable.
> >
> > - Lars
>
> Yes, I'm trying to make this to a generic interface. I'll try to make
> HW/platform related dependency to be configurable and let it more
> generic.
> Thanks for your suggestion.
>
I don't think it makes sense for each arm64 platform to expose an
entropy source via SMC calls in a slightly different way, and model it
as a h/w driver. Instead, we should try to standardize this, and
perhaps expose it via the architectural helpers that already exist
(get_random_seed_long() and friends), so they get plugged into the
kernel random pool driver directly.
Note that in addition to drivers based on vendor SMC calls, we already
have a RNG h/w driver based on OP-TEE as well, where the driver
attaches to a standardized trusted OS interface identified by a UUID,
and which also gets invoked via SMC calls into secure firmware.
On Mon, 2 Dec 2019 16:12:09 +0000
Ard Biesheuvel <[email protected]> wrote:
> (adding some more arm64 folks)
>
> On Fri, 29 Nov 2019 at 11:30, Neal Liu <[email protected]> wrote:
> >
> > On Fri, 2019-11-29 at 18:02 +0800, Lars Persson wrote:
> > > Hi Neal,
> > >
> > > On Wed, Nov 27, 2019 at 3:23 PM Neal Liu <[email protected]> wrote:
> > > >
> > > > For MediaTek SoCs on ARMv8 with TrustZone enabled, peripherals like
> > > > entropy sources is not accessible from normal world (linux) and
> > > > rather accessible from secure world (ATF/TEE) only. This driver aims
> > > > to provide a generic interface to ATF rng service.
> > > >
> > >
> > > I am working on several SoCs that also will need this kind of driver
> > > to get entropy from Arm trusted firmware.
> > > If you intend to make this a generic interface, please clean up the
> > > references to MediaTek and give it a more generic name. For example
> > > "Arm Trusted Firmware random number driver".
> > >
> > > It will also be helpful if the SMC call number is configurable.
> > >
> > > - Lars
> >
> > Yes, I'm trying to make this to a generic interface. I'll try to make
> > HW/platform related dependency to be configurable and let it more
> > generic.
> > Thanks for your suggestion.
> >
>
> I don't think it makes sense for each arm64 platform to expose an
> entropy source via SMC calls in a slightly different way, and model it
> as a h/w driver. Instead, we should try to standardize this, and
> perhaps expose it via the architectural helpers that already exist
> (get_random_seed_long() and friends), so they get plugged into the
> kernel random pool driver directly.
Absolutely. I'd love to see a standard, ARM-specified, virtualizable
RNG that is abstracted from the HW.
> Note that in addition to drivers based on vendor SMC calls, we already
> have a RNG h/w driver based on OP-TEE as well, where the driver
> attaches to a standardized trusted OS interface identified by a UUID,
> and which also gets invoked via SMC calls into secure firmware.
... and probably an unhealthy number of hypervisor-specific hacks that
do the same thing. The sooner we plug this, the better.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
On 12/2/2019 11:11 AM, Marc Zyngier wrote:
> On Mon, 2 Dec 2019 16:12:09 +0000
> Ard Biesheuvel <[email protected]> wrote:
>
>> (adding some more arm64 folks)
>>
>> On Fri, 29 Nov 2019 at 11:30, Neal Liu <[email protected]> wrote:
>>>
>>> On Fri, 2019-11-29 at 18:02 +0800, Lars Persson wrote:
>>>> Hi Neal,
>>>>
>>>> On Wed, Nov 27, 2019 at 3:23 PM Neal Liu <[email protected]> wrote:
>>>>>
>>>>> For MediaTek SoCs on ARMv8 with TrustZone enabled, peripherals like
>>>>> entropy sources is not accessible from normal world (linux) and
>>>>> rather accessible from secure world (ATF/TEE) only. This driver aims
>>>>> to provide a generic interface to ATF rng service.
>>>>>
>>>>
>>>> I am working on several SoCs that also will need this kind of driver
>>>> to get entropy from Arm trusted firmware.
>>>> If you intend to make this a generic interface, please clean up the
>>>> references to MediaTek and give it a more generic name. For example
>>>> "Arm Trusted Firmware random number driver".
>>>>
>>>> It will also be helpful if the SMC call number is configurable.
>>>>
>>>> - Lars
>>>
>>> Yes, I'm trying to make this to a generic interface. I'll try to make
>>> HW/platform related dependency to be configurable and let it more
>>> generic.
>>> Thanks for your suggestion.
>>>
>>
>> I don't think it makes sense for each arm64 platform to expose an
>> entropy source via SMC calls in a slightly different way, and model it
>> as a h/w driver. Instead, we should try to standardize this, and
>> perhaps expose it via the architectural helpers that already exist
>> (get_random_seed_long() and friends), so they get plugged into the
>> kernel random pool driver directly.
>
> Absolutely. I'd love to see a standard, ARM-specified, virtualizable
> RNG that is abstracted from the HW.
Do you think we could use virtio-rng on top of a modified virtio-mmio
which instead of being backed by a hardware mailbox, could use hvc/smc
calls to signal writes to shared memory and get notifications via an
interrupt? This would also open up the doors to other virtio uses cases
beyond just RNG (e.g.: console, block devices?). If this is completely
stupid, then please disregard this comment.
--
Florian
On Mon, Dec 02, 2019 at 07:11:46PM +0000, Marc Zyngier wrote:
> On Mon, 2 Dec 2019 16:12:09 +0000
> Ard Biesheuvel <[email protected]> wrote:
>
> > (adding some more arm64 folks)
> >
> > On Fri, 29 Nov 2019 at 11:30, Neal Liu <[email protected]> wrote:
> > >
> > > On Fri, 2019-11-29 at 18:02 +0800, Lars Persson wrote:
> > > > Hi Neal,
> > > >
> > > > On Wed, Nov 27, 2019 at 3:23 PM Neal Liu <[email protected]> wrote:
> > > > >
> > > > > For MediaTek SoCs on ARMv8 with TrustZone enabled, peripherals like
> > > > > entropy sources is not accessible from normal world (linux) and
> > > > > rather accessible from secure world (ATF/TEE) only. This driver aims
> > > > > to provide a generic interface to ATF rng service.
> > > > >
> > > >
> > > > I am working on several SoCs that also will need this kind of driver
> > > > to get entropy from Arm trusted firmware.
> > > > If you intend to make this a generic interface, please clean up the
> > > > references to MediaTek and give it a more generic name. For example
> > > > "Arm Trusted Firmware random number driver".
> > > >
> > > > It will also be helpful if the SMC call number is configurable.
> > > >
> > > > - Lars
> > >
> > > Yes, I'm trying to make this to a generic interface. I'll try to make
> > > HW/platform related dependency to be configurable and let it more
> > > generic.
> > > Thanks for your suggestion.
> > >
> >
> > I don't think it makes sense for each arm64 platform to expose an
> > entropy source via SMC calls in a slightly different way, and model it
> > as a h/w driver. Instead, we should try to standardize this, and
> > perhaps expose it via the architectural helpers that already exist
> > (get_random_seed_long() and friends), so they get plugged into the
> > kernel random pool driver directly.
>
> Absolutely. I'd love to see a standard, ARM-specified, virtualizable
> RNG that is abstracted from the HW.
Same here. I hacked up some initial code for doing this with KVM [1], but
I'd much rather it was part of a standard service specification so that
we could use the same interface for talking to the firmware and the
hypervisor.
Will
[1] https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=kvm/hvc
On Mon, Dec 02, 2019 at 04:12:09PM +0000, Ard Biesheuvel wrote:
> (adding some more arm64 folks)
>
> On Fri, 29 Nov 2019 at 11:30, Neal Liu <[email protected]> wrote:
> >
> > On Fri, 2019-11-29 at 18:02 +0800, Lars Persson wrote:
> > > Hi Neal,
> > >
> > > On Wed, Nov 27, 2019 at 3:23 PM Neal Liu <[email protected]> wrote:
> > > >
> > > > For MediaTek SoCs on ARMv8 with TrustZone enabled, peripherals like
> > > > entropy sources is not accessible from normal world (linux) and
> > > > rather accessible from secure world (ATF/TEE) only. This driver aims
> > > > to provide a generic interface to ATF rng service.
> > > >
> > >
> > > I am working on several SoCs that also will need this kind of driver
> > > to get entropy from Arm trusted firmware.
> > > If you intend to make this a generic interface, please clean up the
> > > references to MediaTek and give it a more generic name. For example
> > > "Arm Trusted Firmware random number driver".
> > >
> > > It will also be helpful if the SMC call number is configurable.
> > >
> > > - Lars
> >
> > Yes, I'm trying to make this to a generic interface. I'll try to make
> > HW/platform related dependency to be configurable and let it more
> > generic.
> > Thanks for your suggestion.
> >
>
> I don't think it makes sense for each arm64 platform to expose an
> entropy source via SMC calls in a slightly different way, and model it
> as a h/w driver. Instead, we should try to standardize this, and
> perhaps expose it via the architectural helpers that already exist
> (get_random_seed_long() and friends), so they get plugged into the
> kernel random pool driver directly.
>
> Note that in addition to drivers based on vendor SMC calls, we already
> have a RNG h/w driver based on OP-TEE as well, where the driver
> attaches to a standardized trusted OS interface identified by a UUID,
> and which also gets invoked via SMC calls into secure firmware.
Yes, I agree. I had raised the issue internally and forgot to follow up.
I raised this few months back after I read a blog[1]
--
Regards,
Sudeep
[1] https://community.arm.com/developer/ip-products/processors/f/cortex-a-forum/43679/arm-really-should-standardize-an-smc-interface-for-hardware-random-number-generators