[PATCH 1/1] Add RISC-V TEE support
liushiwei
liushiwei at eswincomputing.com
Sat Jan 28 00:33:34 PST 2023
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?
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
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