On Thu May 16, 2024 at 12:55 AM EEST, Haitao Huang wrote: > On Wed, 15 May 2024 01:55:21 -0500, Bojun Zhu <zhubojun.zbj@xxxxxxxxxxxx> > wrote: > > > EDMM's ioctl()s support batch operations, which may be > > time-consuming. Try to explicitly give up the CPU as the prefix > > operation at the every begin of "for loop" in > > sgx_enclave_{ modify_types | restrict_permissions | remove_pages} > > to give other tasks a chance to run, and avoid softlockup warning. > > > > Additionally perform pending signals check as the prefix operation, > > and introduce sgx_check_signal_and_resched(), > > which wraps all the checks. > > > > The following has been observed on Linux v6.9-rc5 with kernel > > preemptions disabled(by configuring "PREEMPT_NONE=y"), when kernel > > is requested to restrict page permissions of a large number of EPC pages. > > > > ------------[ cut here ]------------ > > watchdog: BUG: soft lockup - CPU#45 stuck for 22s! > > ... > > RIP: 0010:sgx_enclave_restrict_permissions+0xba/0x1f0 > > ... > > Call Trace: > > sgx_ioctl > > __x64_sys_ioctl > > x64_sys_call > > do_syscall_64 > > entry_SYSCALL_64_after_hwframe > > ------------[ end trace ]------------ > > > > Signed-off-by: Bojun Zhu <zhubojun.zbj@xxxxxxxxxxxx> > > --- > > arch/x86/kernel/cpu/sgx/ioctl.c | 40 +++++++++++++++++++++++---------- > > 1 file changed, 28 insertions(+), 12 deletions(-) > > > > diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c > > b/arch/x86/kernel/cpu/sgx/ioctl.c > > index b65ab214bdf5..6199f483143e 100644 > > --- a/arch/x86/kernel/cpu/sgx/ioctl.c > > +++ b/arch/x86/kernel/cpu/sgx/ioctl.c > > @@ -365,6 +365,20 @@ static int sgx_validate_offset_length(struct > > sgx_encl *encl, > > return 0; > > } > > +/* > > + * Check signals and invoke scheduler. Return true for a pending signal. > > + */ > > +static bool sgx_check_signal_and_resched(void) > > +{ > > + if (signal_pending(current)) > > + return true; > > + > > + if (need_resched()) > > + cond_resched(); > > + > > + return false; > > +} > > + > > /** > > * sgx_ioc_enclave_add_pages() - The handler for > > %SGX_IOC_ENCLAVE_ADD_PAGES > > * @encl: an enclave pointer > > @@ -409,7 +423,7 @@ static long sgx_ioc_enclave_add_pages(struct > > sgx_encl *encl, void __user *arg) > > struct sgx_enclave_add_pages add_arg; > > struct sgx_secinfo secinfo; > > unsigned long c; > > - int ret; > > + int ret = -ERESTARTSYS; > > if (!test_bit(SGX_ENCL_CREATED, &encl->flags) || > > test_bit(SGX_ENCL_INITIALIZED, &encl->flags)) > > @@ -432,15 +446,8 @@ static long sgx_ioc_enclave_add_pages(struct > > sgx_encl *encl, void __user *arg) > > return -EINVAL; > > for (c = 0 ; c < add_arg.length; c += PAGE_SIZE) { > > - if (signal_pending(current)) { > > - if (!c) > > - ret = -ERESTARTSYS; > > - > > + if (sgx_check_signal_and_resched()) > > break; > > - } > > ERESTARTSYS is only appropriate if we have not EADDed any pages yet. > If we got interrupted in the middle, we should return 0. User space would > check the 'count' returned and decide to recall this ioctl() with > 'offset' reset to the next page, and adjust length. Good catch! Thanks Haitao for the remark. BR, Jarkko