On Tue, Sep 03, 2019 at 05:26:41PM +0300, Jarkko Sakkinen wrote: > From: Sean Christopherson <sean.j.christopher...@intel.com> > > Enclaves are SGX hosted measured and signed software entities. ENCLS[EINIT]
SGX-hosted, measured, and ... > leaf function checks that the enclave has a legit signed measurement and > transforms the enclave to the state ready for execution. The signed > measurement is provided by the caller in the form of SIGSTRUCT data > structure [1]. > > Wrap ENCLS[EINIT] into sgx_einit(). Set MSR_IA32_SGXLEPUBKEYHASH* MSRs to > match the public key contained in the SIGSTRUCT [2]. This sets Linux to > enforce a policy where the provided public key is as long as the signed > measurement matches the enclave contents in memory. That subclause needs to be separated, maybe: ... the provided public key is - as long as the signed measurement matches the the enclave contents - in memory. Provided you mean that, of course. > Add a per-cpu cache to avoid unnecessary reads and write to the MSRs reads and writes? > as they are expensive operations. > > [1] Intel SDM: 37.1.3 ENCLAVE SIGNATURE STRUCTURE (SIGSTRUCT) > [2] Intel SDM: 38.1.4 Intel SGX Launch Control Configuration > > Signed-off-by: Sean Christopherson <sean.j.christopher...@intel.com> > Co-developed-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com> > Signed-off-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com> > --- > arch/x86/kernel/cpu/sgx/main.c | 51 ++++++++++++++++++++++++++++++++++ > arch/x86/kernel/cpu/sgx/sgx.h | 2 ++ > 2 files changed, 53 insertions(+) > > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > index 6b4727df72ca..d3ed742e90fe 100644 > --- a/arch/x86/kernel/cpu/sgx/main.c > +++ b/arch/x86/kernel/cpu/sgx/main.c > @@ -17,6 +17,9 @@ EXPORT_SYMBOL_GPL(sgx_epc_sections); > > int sgx_nr_epc_sections; > > +/* A per-cpu cache for the last known values of IA32_SGXLEPUBKEYHASHx MSRs. > */ > +static DEFINE_PER_CPU(u64 [4], sgx_lepubkeyhash_cache); > + > static struct sgx_epc_page *sgx_section_get_page( > struct sgx_epc_section *section) > { > @@ -106,6 +109,54 @@ void sgx_free_page(struct sgx_epc_page *page) > } > EXPORT_SYMBOL_GPL(sgx_free_page); > > +static void sgx_update_lepubkeyhash_msrs(u64 *lepubkeyhash, bool enforce) > +{ > + u64 *cache; > + int i; > + > + cache = per_cpu(sgx_lepubkeyhash_cache, smp_processor_id()); > + for (i = 0; i < 4; i++) { > + if (enforce || (lepubkeyhash[i] != cache[i])) { > + wrmsrl(MSR_IA32_SGXLEPUBKEYHASH0 + i, lepubkeyhash[i]); > + cache[i] = lepubkeyhash[i]; > + } > + } > +} > + > +/** > + * sgx_einit - initialize an enclave > + * @sigstruct: a pointer a SIGSTRUCT > + * @token: a pointer an EINITTOKEN (optional) > + * @secs: a pointer a SECS That's a strange formulation "a pointer a/an" ? "to" missing? > + * @lepubkeyhash: the desired value for IA32_SGXLEPUBKEYHASHx MSRs > + * > + * Execute ENCLS[EINIT], writing the IA32_SGXLEPUBKEYHASHx MSRs according > + * to @lepubkeyhash (if possible and necessary). > + * > + * Return: > + * 0 on success, > + * -errno or SGX error on failure > + */ > +int sgx_einit(struct sgx_sigstruct *sigstruct, struct sgx_einittoken *token, > + struct sgx_epc_page *secs, u64 *lepubkeyhash) > +{ > + int ret; > + > + if (!boot_cpu_has(X86_FEATURE_SGX_LC)) > + return __einit(sigstruct, token, sgx_epc_addr(secs)); > + > + preempt_disable(); > + sgx_update_lepubkeyhash_msrs(lepubkeyhash, false); > + ret = __einit(sigstruct, token, sgx_epc_addr(secs)); > + if (ret == SGX_INVALID_EINITTOKEN) { > + sgx_update_lepubkeyhash_msrs(lepubkeyhash, true); > + ret = __einit(sigstruct, token, sgx_epc_addr(secs)); > + } > + preempt_enable(); > + return ret; > +} > +EXPORT_SYMBOL(sgx_einit); I was about to ask why isn't this export _GPL() but it goes away in a later patch. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette