The following commit has been merged into the x86/urgent branch of tip:

Commit-ID: 3d7d72a34e05b23e21bafc8bfb861e73c86b31f3 Gitweb: https://git.kernel.org/tip/3d7d72a34e05b23e21bafc8bfb861e73c86b31f3 Author: Jack Wang jinpu.wang@ionos.com AuthorDate: Wed, 06 Sep 2023 15:17:12 +02:00 Committer: Ingo Molnar mingo@kernel.org CommitterDate: Wed, 06 Sep 2023 23:55:09 +02:00

x86/sgx: Break up long non-preemptible delays in sgx_vepc_release()

On large enclaves we hit the softlockup warning with following call trace:

xa_erase() sgx_vepc_release() __fput() task_work_run() do_exit()

The latency issue is similar to the one fixed in:

8795359e35bc ("x86/sgx: Silence softlockup detection when releasing large enclaves")

The test system has 64GB of enclave memory, and all is assigned to a single VM. Release of 'vepc' takes a longer time and causes long latencies, which triggers the softlockup warning.

Add cond_resched() to give other tasks a chance to run and reduce latencies, which also avoids the softlockup detector.

[ mingo: Rewrote the changelog. ]

Fixes: 540745ddbc70 ("x86/sgx: Introduce virtual EPC for use by KVM guests") Reported-by: Yu Zhang yu.zhang@ionos.com Signed-off-by: Jack Wang jinpu.wang@ionos.com Signed-off-by: Ingo Molnar mingo@kernel.org Tested-by: Yu Zhang yu.zhang@ionos.com Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Reviewed-by: Kai Huang kai.huang@intel.com Acked-by: Haitao Huang haitao.huang@linux.intel.com Cc: stable@vger.kernel.org --- 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 c3e37ea..7aaa365 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))