[PATCH 1/1] Add RISC-V TEE support
Atish Patra
atishp at atishpatra.org
Tue Feb 7 14:37:12 PST 2023
On Sat, Jan 28, 2023 at 12:33 AM liushiwei <liushiwei at eswincomputing.com> wrote:
>
> Hi, Atish
> Thank you for your reply.
> I submitted my ideas to https://github.com/riscv-non-isa/riscv-sbi-doc/pull/106 as requested by other members of the email.
> You can preview them at https://github.com/liushiwei007/riscv-sbi-doc/blob/master/riscv-sbi.adoc .
> I'm not sure if I need to send an email to tech-prs at lists.riscv.org or sig-trusted-computing at lists.riscv.org after submitting to riscv-sbi-doc?
> If so, Is it to send the patch of opensbi I submitted before?
>
The Trusted computing SIG evaluates the overall merit and direction of
any TEE related specifications.
The PRS TG will focus more on the SBI specification related parts.
I would recommend you to present your work to Trusted Computing SIG
first so that everybody agrees on the overall direction
for OP-TEE support in RISC-V.
> Regards,
> Liushiwei
>
>
> -----邮件原件-----
> 发件人: Atish Patra [mailto:atishp at atishpatra.org]
> 发送时间: 2023年1月25日 3:12
> 收件人: liushiwei <liushiwei at eswincomputing.com>
> 抄送: Himanshu Chauhan <hchauhan at ventanamicro.com>; opensbi at lists.infradead.org; chenchaokai at eswincomputing.com
> 主题: Re: 答复: [PATCH 1/1] Add RISC-V TEE support
>
> On Wed, Jan 11, 2023 at 11:08 PM liushiwei <liushiwei at eswincomputing.com> wrote:
> >
> > Hi, Himanshu , These are my description:
> >
> > In my design, The entire linux space is called REE (Rich Execution
> > Environment), and TEE OS includes its user state called TEE (Trusted execution environment).
> > adding TEE functionality to opensbi requires two configuration items.
> > For example:
> > add CONFIG_SBI_ECALL_TEE=y in platform/generic/configs/defconfig file.
> > add CONFIG_TEE_LOAD_ADDR=0x27C000000 platform/generic/objects.mk.
> > The value of CONFIG_TEE_LOAD_ADDR depends on the actual memory layout,
> > It's a physical address.
> >
> > When TEE is configured, opensbi adds the following functionality:
> > 1. Boot TEE OS.
> > If TEE is enabled, tee_os_init() is called before entering
> > sbi_hart_switch_mode(). tee_os_init saves the current context,
> > sets a new trap stack address, and runs to CONFIG_TEE_LOAD_ADDR as configured
> > to complete TEE OS initialization. TEE OS returns via ecall, Go to opensbi
> > sbi_ecall_tee_handler and use the characteristic value RETURN_ENTRY_DONE
> > to indicate the return after the TEE OS completes booting. Check whether the
> > TEE OS boot successfully according to the parameter. If fails,
> > the system enters wfi and terminates the startup process of opensbi. If successful,
> > it returns REE to switch into TEE's vector. then trap stack memory is restored,
> > the context is restored, the tee_os_init call is returned,
> > and the rest of the process is performed.
> > 2. REE switches to TEE.
> > When the TEE OS boot successfully, it returns an entry vector for REE into the TEE.
> > It represents various entry points into TEE OS and is stored in opensbi's global variables.
> > It is the optee_vectors_t structure, which contains nine entry cases:
> > 1. yield_smc_entry;
> > 2. fast_smc_entry;
> > 3. cpu_on_entry;
> > 4. cpu_off_entry;
> > 5. cpu_resume_entry;
> > 6. cpu_suspend_entry;
> > 7. fiq_entry;
> > 8. system_off_entry;
> > 9. system_reset_entry;
> > yield_smc_entry means that this function entry TEE will start the thread function
> > and enter the user state of TEE. It may also switch back to REE with RPC function,
> > and then return to TEE after REE completes the corresponding function.
> > For the REE process that sent you this call, it may cause sleep.
> >
> > fast_smc_entry indicates that this is a quick function that returns after
> > the TEE OS does something, and that it does not cause the caller to sleep.
> >
> > yield_smc_entry and fast_smc_entry return opensbi use eigenvalue RETURN_CALL_DONE.
> > for yield_smc_entry, whether the call returns or the RPC returns is decided by linux.
> >
> > cpu_on_entry/cpu_off_entry/cpu_resume_entry/cpu_suspend_entry and
> > fiq_entry/system_off_entry/system_reset_entry they are not implemented currently.
> >
> > 3. TEE switches to REE.
> > opensbi needs to save the context when REE enters the TEE,
> > and restore the context when it returns from the TEE.
> >
> > 4. TEE/REE Request a special function.
> > We have some specific functions, like get hartid from TEE,
> > it need save and restore the TEE context.
> >
> > Data structure.
> > opensbi adds the sbi_save_context declaration
> > struct sbi_save_context {
> > struct sbi_trap_regs regs;
> > unsigned long sepc;
> > unsigned long satp;
> > unsigned long sstatus;
> > unsigned long sie;
> > unsigned long stvec;
> > unsigned long sscratch;
> > unsigned long scounteren;
> > unsigned long scause;
> > unsigned long stval;
> > unsigned long sip;
> > };
> > sbi_save_context include sbi_trap_regs and S mode csr. Used to hold
> > the context of TEE or REE
> >
> > typedef struct optee_vectors {
> > optee_vector_isn_t yield_smc_entry;
> > optee_vector_isn_t fast_smc_entry;
> > optee_vector_isn_t cpu_on_entry;
> > optee_vector_isn_t cpu_off_entry;
> > optee_vector_isn_t cpu_resume_entry;
> > optee_vector_isn_t cpu_suspend_entry;
> > optee_vector_isn_t fiq_entry;
> > optee_vector_isn_t system_off_entry;
> > optee_vector_isn_t system_reset_entry;
> > } optee_vectors_t;
> > optee_vectors represent the various entry points into TEE OS.
> >
> > Variables defined by opensbi
> > optee_vectors_t *optee_vector_table;
> > struct sbi_save_context nsec_cpu_context[OPTEED_CORE_COUNT];
> > struct sbi_save_context sec_cpu_context[OPTEED_CORE_COUNT];
> > struct sbi_trap_regs cpu_start_context[OPTEED_CORE_COUNT];
> > typedef ulong tee_tmp_trap_stack[1024];
> > static tee_tmp_trap_stack tmp_stack[OPTEED_CORE_COUNT];
> >
> > optee_vector_table value is assigned after the TEE OS boot succeeds.
> > nsec_cpu_context and sec_cpu_context is to save the context of TEE and REE,
> > cpu_start_context save the context of opensbi before tee_os_init enter TEE OS,
> > tee_tmp_stack is the trap stack when TEE OS return tee_os_init.
> >
> > Under the current design, REE does not enable interrupts when entering
> > TEE, and the entire TEE, including opensbi, is the process context of linux.
> > TEE processing must be brief and quick.
> >
>
> Great. Thanks. Your PR should include more details like this with proper FID allocation and description.
> In order to make it a standard RISC-V SBI extension, you need to present this in tech-prs mailing list
> (https://lists.riscv.org/g/tech-prs)
> and get it approved within the group. Here is the policy document[1]
>
> https://docs.google.com/document/d/1bQGHU-wD4uN4mU07oH9adpXbH51NqUbFxcL8qTTIqhA/edit
>
> I think it would be good if you can present your work in trusted computing SIG (https://lists.riscv.org/g/sig-trusted-computing) as well.
>
> >
> > Regards,
> > liushiwei
> > -----邮件原件-----
> > 发件人: Himanshu Chauhan [mailto:hchauhan at ventanamicro.com]
> > 发送时间: 2023年1月11日 23:39
> > 收件人: liushiwei <liushiwei at eswincomputing.com>
> > 抄送: opensbi at lists.infradead.org; chenchaokai at eswincomputing.com
> > 主题: Re: 答复: [PATCH 1/1] Add RISC-V TEE support
> >
> > On Wed, Jan 11, 2023 at 08:27:59PM +0800, liushiwei wrote:
> > > Do you mean hardware? Our hardware design referred to arm's
> > > trustzone technology. optee os is a software solution using arm
> > > trustzone hardware, which mainly includes REE(linux), TEE(optee os),
> > > ATF(ARM Trusted firmware), and then our software also developed
> > > these three parts. opensbi is similar to ATF. whether if this is what you want?
> > > The current committed code is not hardware-dependent, but just
> > > continues the idea of this workaround, and we may commit hardware-dependent code later.
> > >
> > No, I meant the software specification.
> >
> > > -----邮件原件-----
> > > 发件人: hchauhan at ventanamicro.com [mailto:hchauhan at ventanamicro.com]
> > > 发送时间: 2023年1月11日 20:03
> > > 收件人: 'liushiwei' <liushiwei at eswincomputing.com>; opensbi at lists.infradead.
> > > org
> > > 抄送: chenchaokai at eswincomputing.com
> > > 主题: RE: [PATCH 1/1] Add RISC-V TEE support
> > >
> > > -----Original Message-----
> > > > From: opensbi <opensbi-bounces at lists.infradead.org> On Behalf Of
> > > > liushiwei
> > > > Sent: 11 January 2023 07:32
> > > > To: opensbi at lists.infradead.org
> > > > Cc: chenchaokai at eswincomputing.com; liushiwei
> > > <liushiwei at eswincomputing.com>
> > > > Subject: [PATCH 1/1] Add RISC-V TEE support
> > >
> > > >RISC-V Trusted Executable Environment security software includes
> > > >linux,
> > > opensbi, and OP-TEE OS. linux is the non-secure domain, and OP-TEE
> > > OS is the secure domain. At boot time, opensbi boots OP->TEE OS and then starts linux.
> > > At runtime, opensbi acts as a secure monitor, responsible for
> > > context saving and restoring when switching between linux and OP-TEE OS.
> > > >TEE function is off by default, when using configuration is added
> > > >in the
> > > config and objects file, such as platform/generic/configs/defconfig
> > > add CONFIG_SBI_ECALL_TEE = y, In the >platform/generic/objects.mk
> > > add CONFIG_TEE_LOAD_ADDR = 0x27c000000, CONFIG_TEE_LOAD_ADDR is the
> > > starting address of the OP-TEE OS.
> > >
> > > Hi Liushiwei,
> > >
> > > Was there any formal specification or draft for this? Could you
> > > please point me to the draft or specification?
> > >
> > > Regards
> > > Himanshu
> > >
> > > --
> > > opensbi mailing list
> > > opensbi at lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/opensbi
> > >
> >
> >
> > --
> > opensbi mailing list
> > opensbi at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/opensbi
>
>
>
> --
> Regards,
> Atish
>
--
Regards,
Atish
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