[U-Boot] [PATCH v4 0/2] Fix CAAM for TrustZone enable for warp7
V4: - Fix dim-witted omission of #include <fsl_sec.h> to remove warning
V3: - Changed location of sec_init() from warp.c::board_init() to soc.c::arch_misc_init() which will allow any i.MX7 which defines CONFIG_FSL_CAAM to forget about running sec_init().
V2: - Add an explicit assignment of JRMID when setting job-ring ownership Required on my reference part where the JRMID field is not set on the third job-ring
V1: This series is the u-boot fix to a problem we encountered when enabling OPTEE/TrustZone on the WaRP7. The symptom is once TrustZone is activated the first page of CAAM registers becomes read-only, read-zero from the perspective of Linux and other non TrustZone contexts.
Offlining the problem with Peng Fan[1] we eventually came to realise the problem could be worked around by
1. Making Linux skip RNG initialisation - a set of patches should be hitting LKML to do just that.
2. Initialising the RNG either from u-boot or OPTEE. In this case u-boot is the right place to-do that because there's upstream code in u-boot that just works. Patch #2 does that for the WaRP7.
3. Ensuring the job-ring registers are assigned to the non TrustZone mode. On the i.MX7 after the BootROM runs the job-ring registers are assigned to TrustZone. Patch #1 does that for all CAAM hardware.
On point #3 this ordinarily isn't a problem because unless TrustZone is activated the restrictions on the job-ring registers don't kick in, its only after enabling TrustZone that Linux will loose access to the job-ring registers.
Finally should OPTEE or another TEE want to do things with the job-ring registers it will have sufficient privilege to assign whichever job-ring registers it wants to OPTEE/TEE but will naturally then have to arbitrate with Linux to inform the Kernel CAAM driver which job-ring registers it can and cannot access.
That arbitration process is for a future putative OPTEE/TEE CAAM driver to solve and is out of scope of this patchset.
[1] Thanks for all of your help BTW - Peng, there's no way this would be working without you giving direction on how.
Bryan O'Donoghue (2): drivers/crypto/fsl: assign job-rings to non-TrustZone imx: mx7: run sec_init for CAAM RNG
arch/arm/mach-imx/mx7/soc.c | 5 +++++ drivers/crypto/fsl/jr.c | 9 +++++++++ drivers/crypto/fsl/jr.h | 2 ++ 3 files changed, 16 insertions(+)
After enabling TrustZone various parts of the CAAM silicon become inaccessible to non TrustZone contexts. The job-ring registers are designed to allow non TrustZone contexts like Linux to still submit jobs to CAAM even after TrustZone has been enabled.
The default job-ring permissions after the BootROM look like this for job-ring zero.
ms=0x00008001 ls=0x00008001
The MS field is JRaMIDR_MS (job ring MID most significant).
Referring to "Security Reference Manual for i.MX 7Dual and 7Solo Applications Processors, Rev. 0, 03/2017" section 8.10.4 we see that JROWN_NS controls whether or not a job-ring is accessible from non TrustZone.
Bit 15 (TrustZone) is the logical inverse of bit 3 hence the above value of 0x8001 shows that JROWN_NS=0 and TrustZone=1.
Clearly then as soon as TrustZone becomes active the job-ring registers are no longer accessible from Linux, which is not what we want.
This patch explicitly sets all job-ring registers to JROWN_NS=1 (non TrustZone) by default and to the Non-Secure MID 001. Both settings are required to successfully assign a job-ring to non-secure mode. If a piece of TrustZone firmware requires ownership of job-ring registers it can unset the JROWN_NS bit itself.
This patch in conjunction with a modification of the Linux kernel to skip HWRNG initialisation makes CAAM usable to Linux with TrustZone enabled.
Signed-off-by: Bryan O'Donoghue bryan.odonoghue@linaro.org Cc: Fabio Estevam fabio.estevam@nxp.com Cc: Peng Fan peng.fan@nxp.com Cc: Alex Porosanu alexandru.porosanu@nxp.com Cc: Ruchika Gupta ruchika.gupta@nxp.com Cc: Aneesh Bansal aneesh.bansal@nxp.com Link: https://github.com/OP-TEE/optee_os/issues/1408 Link: https://tinyurl.com/yam5gv9a Tested-by: Lukas Auer lukas.auer@aisec.fraunhofer.de --- drivers/crypto/fsl/jr.c | 9 +++++++++ drivers/crypto/fsl/jr.h | 2 ++ 2 files changed, 11 insertions(+)
diff --git a/drivers/crypto/fsl/jr.c b/drivers/crypto/fsl/jr.c index a6dad01..34bd070 100644 --- a/drivers/crypto/fsl/jr.c +++ b/drivers/crypto/fsl/jr.c @@ -579,6 +579,8 @@ int sec_init_idx(uint8_t sec_idx) { ccsr_sec_t *sec = (void *)SEC_ADDR(sec_idx); uint32_t mcr = sec_in32(&sec->mcfgr); + uint32_t jrown_ns; + int i; int ret = 0;
#ifdef CONFIG_FSL_CORENET @@ -634,6 +636,13 @@ int sec_init_idx(uint8_t sec_idx) #endif #endif
+ /* Set ownership of job rings to non-TrustZone mode by default */ + for (i = 0; i < ARRAY_SIZE(sec->jrliodnr); i++) { + jrown_ns = sec_in32(&sec->jrliodnr[i].ms); + jrown_ns |= JROWN_NS | JRMID_NS; + sec_out32(&sec->jrliodnr[i].ms, jrown_ns); + } + ret = jr_init(sec_idx); if (ret < 0) { printf("SEC initialization failed\n"); diff --git a/drivers/crypto/fsl/jr.h b/drivers/crypto/fsl/jr.h index f546226..ef515e7 100644 --- a/drivers/crypto/fsl/jr.h +++ b/drivers/crypto/fsl/jr.h @@ -34,6 +34,8 @@ #define JRNSLIODN_MASK 0x0fff0000 #define JRSLIODN_SHIFT 0 #define JRSLIODN_MASK 0x00000fff +#define JROWN_NS 0x00000008 +#define JRMID_NS 0x00000001
#define JQ_DEQ_ERR -1 #define JQ_DEQ_TO_ERR -2
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Bryan O'Donoghue