On Mon, 2021-03-01 at 09:29 -0800, Sean Christopherson wrote:
> 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.
Good point. Thanks for educating me :)
>
> 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))
Will do in your way. Thanks!
>
> > + /*
> > + * 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
