On Mon, 24 Jan 2022 11:55:10 -0600, Jarkko Sakkinen <jarkko@xxxxxxxxxx>
wrote:
On Mon, Jan 24, 2022 at 07:42:08PM +0200, Jarkko Sakkinen wrote:
On Sat, Jan 22, 2022 at 01:15:01PM -0600, Haitao Huang wrote:
> Hi Dave,
>
> On Fri, 21 Jan 2022 13:57:50 -0600, Dave Hansen
<dave.hansen@xxxxxxxxx>
> wrote:
>
> > Hi Everyone,
> >
> > There are a few SGX fixes that have showed up in the last week or
so,
> > mostly around RAS and fixing the backing storage issues. Could
folks
> > please give this branch a good thrashing?
> >
> > >
https://git.kernel.org/pub/scm/linux/kernel/git/daveh/devel.git/log/?h=x86/sgx
> >
> > I'm planning to send this bunch up to Linus after 5.17-rc1 comes
out.
> >
> > Kristen, I really dug into the changelogs of your two patches to
make it
> > more clear that they are bugfix and stable@ material. I'd
appreciate
> > some additional eyeballs there.
>
> When testing this with a large enclave loaded by Intel runtime, we
saw it
> hang
> on EADD ioctl and the ioctl never returns.
>
> Also noticed the selftest fails on oversub but the return errno is
EINTR not
> ENOMEM as expected.
>
> When user space register signal handler with SA_RESTART flag, EINTR
would
> be an auto restart of ioctl. So that might be what's going on with
Intel
> runtime test. And I suspect following code may cause infinite restart
of the
> ioctl:
>
> struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
> {
> struct sgx_epc_page *page;
>
> for ( ; ; ) {
> page = __sgx_alloc_epc_page();
> if (!IS_ERR(page)) {
> page->owner = owner;
> break;
> }
>
> if (list_empty(&sgx_active_page_list))<-- should also check
> sgx_nr_available_backing_pages?
> return ERR_PTR(-ENOMEM);
I don't think so but why do you think it should?
I was thinking no point to continue if
(atomic_long_read(&sgx_nr_available_backing_pages)==0).
We just failed on finding available EPC above in __sgx_alloc_epc_page. So
if we can't swap, then nothing we can do, right?
BR
Haitao
