The ARM architected TRNG firmware interface, described in ARM spec DEN0098[1], defines an ARM SMCCC based interface to a true random number generator, provided by firmware.
This is the arm64 implementation of that interface, implemented in the arch_get_random_*() code. Patch 1/2 introduces the SMCCC function identifiers, this is extracted from Ard's patch, to avoid dependencies between the several patches floating around (ARM, KVM, arm64). Patch 2/2 detects the interface and calls into the firmware upon a call to arch_get_random_seed_long(). Support for the "early" variant is under investigation. This was tested on: - QEMU -kernel (no SMCCC, regression test) - Juno w/ standard firmware (SMCCC, but no TRNG: regression test) - Juno w/ "fake TRNG" firmware (to verify "random" numbers) - Juno w/ prototype of the h/w Trusted RNG support - mainline KVM (SMCCC, but no TRNG: regression test) - Ard's KVM patch (plus hack to inject fake numbers for verification purposes) Cheers, Andre [1] https://developer.arm.com/documentation/den0098/latest/ Andre Przywara (1): arm64: Add support for SMCCC TRNG firmware interface Ard Biesheuvel (1): firmware: smccc: Add SMCCC TRNG function call IDs arch/arm64/include/asm/archrandom.h | 83 +++++++++++++++++++++++++---- include/linux/arm-smccc.h | 31 +++++++++++ 2 files changed, 104 insertions(+), 10 deletions(-) -- 2.17.1
