On Fri Aug 18, 2023 at 9:07 PM EEST, Jack Wang wrote:

We hit softlocup with following call trace:

? asm_sysvec_apic_timer_interrupt+0x16/0x20 xa_erase+0x21/0xb0 ? sgx_free_epc_page+0x20/0x50 sgx_vepc_release+0x75/0x220 __fput+0x89/0x250 task_work_run+0x59/0x90 do_exit+0x337/0x9a0

Similar like commit 8795359e35bc ("x86/sgx: Silence softlockup detection when releasing large enclaves"). The test system has 64GB of enclave memory, and all assigned to a single VM. Release vepc take longer time and triggers the softlockup warning.

Add cond_resched() to give other tasks a chance to run and placate the softlockup detector.

Cc: Jarkko Sakkinen jarkko@kernel.org Cc: Haitao Huang haitao.huang@linux.intel.com Cc: stable@vger.kernel.org Fixes: 540745ddbc70 ("x86/sgx: Introduce virtual EPC for use by KVM guests") Reported-by: Yu Zhang yu.zhang@ionos.com Tested-by: Yu Zhang yu.zhang@ionos.com Acked-by: Haitao Huang haitao.huang@linux.intel.com Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Jack Wang jinpu.wang@ionos.com

---

v3:

• improve commit message as suggested.
• Add cond_resched() to the 3rd loop too.

arch/x86/kernel/cpu/sgx/virt.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c index c3e37eaec8ec..7aaa3652e31d 100644 --- a/arch/x86/kernel/cpu/sgx/virt.c +++ b/arch/x86/kernel/cpu/sgx/virt.c @@ -204,6 +204,7 @@ static int sgx_vepc_release(struct inode *inode, struct file *file) continue; xa_erase(&vepc->page_array, index);

• cond_resched();
  

  }

/* @@ -222,6 +223,7 @@ static int sgx_vepc_release(struct inode *inode, struct file *file) list_add_tail(&epc_page->list, &secs_pages); xa_erase(&vepc->page_array, index);

• cond_resched();
  

  }

/* @@ -243,6 +245,7 @@ static int sgx_vepc_release(struct inode *inode, struct file *file) if (sgx_vepc_free_page(epc_page)) list_add_tail(&epc_page->list, &secs_pages);

• cond_resched();
  

  }

if (!list_empty(&secs_pages)) -- 2.34.1

Just acknowledging that my reviewed-by still holds for this patch.

BR, Jarkko