On Mon, Mar 01, 2021, Kai Huang wrote:
> diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
> index 7449ef33f081..a7dc86e87a09 100644
> --- a/arch/x86/kernel/cpu/sgx/encl.c
> +++ b/arch/x86/kernel/cpu/sgx/encl.c
> @@ -381,6 +381,26 @@ const struct vm_operations_struct sgx_vm_ops = {
> .access = sgx_vma_access,
> };
>
> +static void sgx_encl_free_epc_page(struct sgx_epc_page *epc_page)
> +{
> + int ret;
> +
> + WARN_ON_ONCE(epc_page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED);
> +
> + ret = __eremove(sgx_get_epc_virt_addr(epc_page));
> + if (WARN_ONCE(ret, "EREMOVE returned %d (0x%x)", ret, ret)) {
This can be ENCLS_WARN, especially if you're printing a separate error message
about leaking the page. That being said, I'm not sure a seperate error message
is a good idea. If other stuff gets dumped to the kernel log between the WARN
and the pr_err_once(), it may not be clear to admins that the two events are
directly connected. It's even possible the prints could come from two different
CPUs.
Why not dump a short blurb in the WARN itself? The error message can be thrown
in a define if the line length is too obnoxious (it's ~109 chars if embedded
directly).
#define EREMOVE_ERROR_MESSAGE \
"EREMOVE returned %d (0x%x). EPC page leaked, reboot recommended."
if (WARN_ONCE(ret, EREMOVE_ERROR_MESSAGE, ret, ret))
> + /*
> + * Give a message to remind EPC page is leaked, and requires
> + * machine reboot to get leaked pages back. This can be improved
> + * in the future by adding stats of leaked pages, etc.
> + */
> + pr_err_once("EPC page is leaked. Require machine reboot to get leaked pages back.\n");
> + return;
> + }
> +
> + sgx_free_epc_page(epc_page);
> +}
> +
> /**
> * sgx_encl_release - Destroy an enclave instance
> * @kref: address of a kref inside &sgx_encl
