On Tue, Feb 16, 2021 at 10:33:17AM +0200, Jarkko Sakkinen wrote:
> On Tue, Feb 16, 2021 at 04:55:49AM +0000, Huang, Kai wrote:
> > >
> > > On Tue, Feb 16, 2021 at 05:08:20AM +0200, Jarkko Sakkinen wrote:
> > > > On Sun, Feb 14, 2021 at 02:29:15AM +1300, Kai Huang wrote:
> > > > > From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> > > > >
> > > > > The host kernel must intercept ECREATE to be able to impose policies
> > > > > on guests. When it does this, the host kernel runs ECREATE against
> > > > > the userspace mapping of the virtualized EPC.
> > > > >
> > > > > Provide wrappers around __ecreate() and __einit() to hide the
> > > > > ugliness of overloading the ENCLS return value to encode multiple
> > > > > error formats in a single int. KVM will trap-and-execute ECREATE
> > > > > and EINIT as part of SGX virtualization, and on an exception, KVM
> > > > > needs the trapnr so that it can inject the correct fault into the guest.
> > > > >
> > > > > Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> > > > > Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
> > > > > ---
> > > > > v4->v5:
> > > > >
> > > > > - No code change.
> > > > >
> > > > > v3->v4:
> > > > >
> > > > > - Added one new line before last return in sgx_virt_einit(), per Jarkko.
> > > > >
> > > > > v2->v3:
> > > > >
> > > > > - Added kdoc for sgx_virt_ecreate() and sgx_virt_einit(), per Jarkko.
> > > > > - Changed to use CONFIG_X86_SGX_KVM.
> > > > >
> > > > > ---
> > > > > arch/x86/include/asm/sgx.h | 16 ++++++
> > > > > arch/x86/kernel/cpu/sgx/virt.c | 94
> > > > > ++++++++++++++++++++++++++++++++++
> > > > > 2 files changed, 110 insertions(+)
> > > > > create mode 100644 arch/x86/include/asm/sgx.h
> > > > >
> > > > > diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
> > > > > new file mode 100644 index 000000000000..8a3ea3e1efbe
> > > > > --- /dev/null
> > > > > +++ b/arch/x86/include/asm/sgx.h
> > > > > @@ -0,0 +1,16 @@
> > > > > +/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _ASM_X86_SGX_H
> > > > > +#define _ASM_X86_SGX_H
> > > > > +
> > > > > +#include <linux/types.h>
> > > > > +
> > > > > +#ifdef CONFIG_X86_SGX_KVM
> > > > > +struct sgx_pageinfo;
> > > > > +
> > > > > +int sgx_virt_ecreate(struct sgx_pageinfo *pageinfo, void __user *secs,
> > > > > + int *trapnr);
> > > > > +int sgx_virt_einit(void __user *sigstruct, void __user *token,
> > > > > + void __user *secs, u64 *lepubkeyhash, int *trapnr);
> > > >
> > > > s/virt/vepc/g
> >
> > No. The two are related to enclave construction (from guest), not EPC.
> >
> > For instance, what does ECREATE mean for virtual EPC? ECREATE is meaningful for enclave.
> >
> > > >
> > > > > +#endif
> > > > > +
> > > > > +#endif /* _ASM_X86_SGX_H */
> > > > > diff --git a/arch/x86/kernel/cpu/sgx/virt.c
> > > > > b/arch/x86/kernel/cpu/sgx/virt.c index 47542140f8c1..016bad7cff8d
> > > > > 100644
> > > > > --- a/arch/x86/kernel/cpu/sgx/virt.c
> > > > > +++ b/arch/x86/kernel/cpu/sgx/virt.c
> > > >
> > > > Rename as vepc.c.
> >
> > No. This file contains more than virtual EPC implementation, but also other staff like sgx_virt_ecreate()/sgx_virt_einit(), which are used by KVM to run ECREATE/EINIT on behalf of guest.
> >
> > > >
> > > > > @@ -257,3 +257,97 @@ int __init sgx_vepc_init(void)
> > > > >
> > > > > return misc_register(&sgx_vepc_dev); }
> > > > > +
> > > > > +/**
> > > > > + * sgx_virt_ecreate() - Run ECREATE on behalf of guest
> > > > > + * @pageinfo: Pointer to PAGEINFO structure
> > > > > + * @secs: Userspace pointer to SECS page
> > > > > + * @trapnr: trap number injected to guest in case of ECREATE error
> > > > > + *
> > > > > + * Run ECREATE on behalf of guest after KVM traps ECREATE for the
> > > > > +purpose
> > > > > + * of enforcing policies of guest's enclaves, and return the trap
> > > > > +number
> > > > > + * which should be injected to guest in case of any ECREATE error.
> > > > > + *
> > > > > + * Return:
> > > > > + * - 0: ECREATE was successful.
> > > > > + * - -EFAULT: ECREATE returned error.
> > > > > + */
> > > > > +int sgx_virt_ecreate(struct sgx_pageinfo *pageinfo, void __user *secs,
> > > > > + int *trapnr)
> > > > > +{
> > > > > + int ret;
> > > > > +
> > > > > + /*
> > > > > + * @secs is userspace address, and it's not guaranteed @secs points at
> > > > > + * an actual EPC page. It's also possible to generate a kernel mapping
> > > > > + * to physical EPC page by resolving PFN but using __uaccess_xx() is
> > > > > + * simpler.
> > > > > + */
> > > > > + __uaccess_begin();
> > > > > + ret = __ecreate(pageinfo, (void *)secs);
> > > > > + __uaccess_end();
> > > > > +
> > > > > + if (encls_faulted(ret)) {
> > > > > + *trapnr = ENCLS_TRAPNR(ret);
> > > > > + return -EFAULT;
> > > > > + }
> > > > > +
> > > > > + /* ECREATE doesn't return an error code, it faults or succeeds. */
> > > > > + WARN_ON_ONCE(ret);
> > > >
> > > > Empty line.
> > > >
> > > > > + return 0;
> > > > > +}
> > > > > +EXPORT_SYMBOL_GPL(sgx_virt_ecreate);
> > > > > +
> > > > > +static int __sgx_virt_einit(void __user *sigstruct, void __user *token,
> > > > > + void __user *secs)
> > > > > +{
> > > > > + int ret;
> > > > > +
> > > > > + __uaccess_begin();
> > > > > + ret = __einit((void *)sigstruct, (void *)token, (void *)secs);
> > > > > + __uaccess_end();
> > > >
> > > > Ditto.
> > > >
> > > > > + return ret;
> > > > > +}
> > > > > +
> > > > > +/**
> > > > > + * sgx_virt_einit() - Run EINIT on behalf of guest
> > > > > + * @sigstruct: Userspace pointer to SIGSTRUCT structure
> > > > > + * @token: Userspace pointer to EINITTOKEN structure
> > > > > + * @secs: Userspace pointer to SECS page
> > > > > + * @lepubkeyhash: Pointer to guest's *virtual* SGX_LEPUBKEYHASH MSR
> > > > > + * values
> > > > > + * @trapnr: trap number injected to guest in case of EINIT error
> > > > > + *
> > > > > + * Run EINIT on behalf of guest after KVM traps EINIT. If SGX_LC is
> > > > > +available
> > > > > + * in host, SGX driver may rewrite the hardware values at wish,
> > > > > +therefore KVM
> > > > > + * needs to update hardware values to guest's virtual MSR values in
> > > > > +order to
> > > > > + * ensure EINIT is executed with expected hardware values.
> > > > > + *
> > > > > + * Return:
> > > > > + * - 0: EINIT was successful.
> > > > > + * - -EFAULT: EINIT returned error.
> > > > > + */
> > > > > +int sgx_virt_einit(void __user *sigstruct, void __user *token,
> > > > > + void __user *secs, u64 *lepubkeyhash, int *trapnr) {
> > > > > + int ret;
> > > > > +
> > > > > + if (!boot_cpu_has(X86_FEATURE_SGX_LC)) {
> > > > > + ret = __sgx_virt_einit(sigstruct, token, secs);
> > > > > + } else {
> > > > > + preempt_disable();
> > > > > +
> > > > > + sgx_update_lepubkeyhash(lepubkeyhash);
> > > > > +
> > > > > + ret = __sgx_virt_einit(sigstruct, token, secs);
> > > > > + preempt_enable();
> > > > > + }
> > > > > +
> > > > > + if (encls_faulted(ret)) {
> > > > > + *trapnr = ENCLS_TRAPNR(ret);
> > > > > + return -EFAULT;
> > > > > + }
> > > > > +
> > > > > + return ret;
> > > > > +}
> > > > > +EXPORT_SYMBOL_GPL(sgx_virt_einit);
> > >
> > > Remove exports.
> >
> > Why? KVM needs to use them in later patches.
>
> Because they are only required for LKM's.
I mean when LKM needs to call kernel functions.
Right, KVM can be compiled as LKM.
/Jarkko
