> -----Original Message-----
> From: Haitao Huang <haitao.huang@xxxxxxxxxxxxxxx>
> Sent: Thursday, August 11, 2022 7:30 PM
> To: Dhanraj, Vijay <vijay.dhanraj@xxxxxxxxx>; Jarkko Sakkinen
> <jarkko@xxxxxxxxxx>
> Cc: linux-sgx@xxxxxxxxxxxxxxx; Chatre, Reinette
> <reinette.chatre@xxxxxxxxx>; dave.hansen@xxxxxxxxxxxxxxx; Huang, Haitao
> <haitao.huang@xxxxxxxxx>
> Subject: Re: [PATCH] Add SGX selftest `augment_via_eaccept_long`
>
> Hi Jarkko
>
> On Wed, 10 Aug 2022 20:50:54 -0500, Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> wrote:
>
> > On Thu, Aug 11, 2022 at 04:36:57AM +0300, Jarkko Sakkinen wrote:
> >> On Thu, Aug 11, 2022 at 04:01:15AM +0300, Jarkko Sakkinen wrote:
> >> > On Wed, Aug 10, 2022 at 12:09:56AM +0000, Dhanraj, Vijay wrote:
> >> > >
> >> > >
> >> > > > -----Original Message-----
> >> > > > From: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> >> > > > Sent: Tuesday, August 9, 2022 11:53 AM
> >> > > > To: Dhanraj, Vijay <vijay.dhanraj@xxxxxxxxx>
> >> > > > Cc: linux-sgx@xxxxxxxxxxxxxxx; Chatre, Reinette
> >> > > > <reinette.chatre@xxxxxxxxx>; dave.hansen@xxxxxxxxxxxxxxx;
> >> > > > Huang,
> >> Haitao
> >> > > > <haitao.huang@xxxxxxxxx>
> >> > > > Subject: Re: [PATCH] Add SGX selftest
> >> > > > `augment_via_eaccept_long`
> >> > > >
> >> > > > On Tue, Aug 09, 2022 at 05:08:21PM +0000, Dhanraj, Vijay wrote:
> >> > > > >
> >> > > > >
> >> > > > > > -----Original Message-----
> >> > > > > > From: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> >> > > > > > Sent: Tuesday, August 9, 2022 9:10 AM
> >> > > > > > To: Dhanraj, Vijay <vijay.dhanraj@xxxxxxxxx>
> >> > > > > > Cc: linux-sgx@xxxxxxxxxxxxxxx; Chatre, Reinette
> >> > > > > > <reinette.chatre@xxxxxxxxx>; dave.hansen@xxxxxxxxxxxxxxx;
> >> Huang,
> >> > > > > > Haitao <haitao.huang@xxxxxxxxx>
> >> > > > > > Subject: Re: [PATCH] Add SGX selftest
> >> `augment_via_eaccept_long`
> >> > > > > >
> >> > > > > > On Tue, Aug 09, 2022 at 01:45:35PM +0300, Jarkko Sakkinen
> >> wrote:
> >> > > > > > > On Mon, Aug 08, 2022 at 06:29:13PM +0300, Jarkko Sakkinen
> >> wrote:
> >> > > > > > > > On Mon, Aug 08, 2022 at 01:00:54PM +0000, Dhanraj,
> >> > > > > > > > Vijay
> >> wrote:
> >> > > > > > > > >
> >> > > > > > > > > > -----Original Message-----
> >> > > > > > > > > > From: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> >> > > > > > > > > > Sent: Monday, August 8, 2022 5:18 AM
> >> > > > > > > > > > To: Dhanraj, Vijay <vijay.dhanraj@xxxxxxxxx>
> >> > > > > > > > > > Cc: linux-sgx@xxxxxxxxxxxxxxx; Chatre, Reinette
> >> > > > > > > > > > <reinette.chatre@xxxxxxxxx>;
> >> dave.hansen@xxxxxxxxxxxxxxx;
> >> > > > > > > > > > Huang, Haitao <haitao.huang@xxxxxxxxx>
> >> > > > > > > > > > Subject: Re: [PATCH] Add SGX selftest
> >> > > > > > > > > > `augment_via_eaccept_long`
> >> > > > > > > > > >
> >> > > > > > > > > > On Thu, Aug 04, 2022 at 01:14:56PM -0700,
> >> > > > > > > > > > vijay.dhanraj@xxxxxxxxx
> >> > > > > > wrote:
> >> > > > > > > > > > > From: Vijay Dhanraj <vijay.dhanraj@xxxxxxxxx>
> >> > > > > > > > > > >
> >> > > > > > > > > > > This commit adds a new test case which is same as
> >> > > > > > > > > > > `augment_via_eaccept` but adds more number of EPC
> >> pages to
> >> > > > > > > > > > > stress test
> >> > > > > > > > > > `EAUG` via `EACCEPT`.
> >> > > > > > > > > > >
> >> > > > > > > > > > > Signed-off-by: Vijay Dhanraj
> >> <vijay.dhanraj@xxxxxxxxx>
> >> > > > > > > > > > > Signed-off-by: Haitao Huang
> >> <haitao.huang@xxxxxxxxxxxxxxx>
> >> > > > > > > > > >
> >> > > > > > > > > > Hey, to reproduce the original issue: does it
> >> reproduce on
> >> > > > > > > > > > VM or should I run baremetal kernel?
> >> > > > > > > > > >
> >> > > > > > > > > > BR, Jarkko
> >> > > > > > > > >
> >> > > > > > > > > Hi Jarkko, The issue should be reproducible on
> >> baremetal kernel.
> >> > > > > > > >
> >> > > > > > > > Thanks.
> >> > > > > > >
> >> > > > > > > I need comment out other tests in order to make sane out
> >> > > > > > > of
> >> this
> >> > > > > > > :-)
> >> > > > > > >
> >> > > > > > > Mentioning this because came into realization that stress
> >> tests
> >> > > > > > > should be IMHO moved each to a separate binary (so that
> >> they can
> >> > > > > > > be run separately). Just a note (TODO) to myself.
> >> > > > > > >
> >> > > > > > > I'll work on this today again and *possibly* split your
> >> test to
> >> > > > > > > its own application to get a starting point for
> >> forementioned.
> >> > > > > >
> >> > > > > > I got
> >> > > > > >
> >> > > > > > # RUN enclave.augment_via_eaccept_long ...
> >> > > > > > # main.c:1241:augment_via_eaccept_long:test enclave:
> >> total_size =
> >> > > > > > 8192,
> >> > > > > > seg->size = 8192 #
> >> > > > > > seg->main.c:1241:augment_via_eaccept_long:test
> >> enclave:
> >> > > > > > total_size = 12288, seg->size = 4096 #
> >> > > > > > main.c:1241:augment_via_eaccept_long:test enclave:
> >> > > > > > total_size
> >> =
> >> > > > > > 36864,
> >> > > > > > seg->size = 24576 #
> >> > > > > > seg->main.c:1241:augment_via_eaccept_long:test
> >> enclave:
> >> > > > > > total_size = 40960, seg->size = 4096 #
> >> > > > > > main.c:1259:augment_via_eaccept_long:mmaping pages at end
> >> > > > > > of
> >> > > > enclave...
> >> > > > > > # main.c:1273:augment_via_eaccept_long:Entering enclave to
> >> > > > > > run EACCEPT for each page of 8589934592 bytes may take a while
> ...
> >> > > > > > # OK enclave.augment_via_eaccept_long
> >> > > > > >
> >> > > > > > The CPU used for testing was according to /proc/cpuinfo:
> >> > > > > >
> >> > > > > > model name : Intel(R) Xeon(R) Gold 6338 CPU @ 2.00GHz
> >> > > > > >
> >> > > > > > I have couple of queries:
> >> > > > > >
> >> > > > > > 1. Is it possible to get dmesg output?
> >> > > > > I did check the dmesg output but couldn't find anything
> >> > > > > related
> >> to the
> >> > > > failure. Just the general log messages.
> >> > > > >
> >> > > > > > 2. Do I have to repeat the test multiple times, or does it
> >> > > > > > occur unconditionaly?
> >> > > > > >
> >> > > > > I was able to repro every time but it was a bit sporadic for
> >> Haitao.
> >> > > > >
> >> > > > > > BR, Jarkko
> >> > > > >
> >> > > > > Also, did you set the PRMRR size to 2GB per socket in the BIOS?
> >> The
> >> > > > > issue is only reproduced for oversubscribed scenario. When I
> >> set my
> >> > > > > PRMRR to 64GB per socket, I wasn't able to repro the issue.
> >> > > >
> >> > > > I need to revisit this.
> >> > > >
> >> > > > Can you simply run test_sgx with gdb and see where it hits?
> >> > > > HOST_CFLAGS has apparently "-g" already.
> >> > > >
> >> > > > > Regards, Vijay
> >> > > >
> >> > > > BR, Jarkko
> >> > >
> >> > > I am able to repro the issue when I reduce the PRMRR to 2B/socket
> >> but not but not able to break on the assertion failure with gdb. I
> >> also enabled debug attribute in the secs but still no avail. Anything
> >> I am missing here?
> >> > >
> >> > > diff --git a/tools/testing/selftests/sgx/load.c
> >> b/tools/testing/selftests/sgx/load.c
> >> > > index 7de1b15c90b1..c4bccd3f5f17 100644
> >> > > --- a/tools/testing/selftests/sgx/load.c
> >> > > +++ b/tools/testing/selftests/sgx/load.c
> >> > > @@ -87,7 +87,7 @@ static bool encl_ioc_create(struct encl *encl)
> >> > >
> >> > > memset(secs, 0, sizeof(*secs));
> >> > > secs->ssa_frame_size = 1;
> >> > > - secs->attributes = SGX_ATTR_MODE64BIT;
> >> > > + secs->attributes = SGX_ATTR_MODE64BIT | SGX_ATTR_DEBUG;
> >> > > secs->xfrm = 3;
> >> > > secs->base = encl->encl_base;
> >> > > secs->size = encl->encl_size;
> >> > >
> >> > > Regards, Vijay
> >> >
> >> > I get also full pass with 2GB configuration (and also observed that
> >> > kselftest runs much faster with this configuration).
> >> >
> >> > But I looked at sgx_alloc_epc_page() and saw this:
> >> >
> >> > if (list_empty(&sgx_active_page_list))
> >> > return ERR_PTR(-ENOMEM);
> >> >
> >> > if (!reclaim) {
> >> > page = ERR_PTR(-EBUSY);
> >> > break;
> >> > }
> >> >
> >> > In sgx_vma_fault(), when running completely out of reclaimable
> >> > pages,
> >> this
> >> > causes VM_FAULT_SIGBUS returned instead of VM_FAULT_NOPAGE:
> >> >
> >> > entry = sgx_encl_load_page(encl, addr, vma->vm_flags);
> >> > if (IS_ERR(entry)) {
> >> > mutex_unlock(&encl->lock);
> >> >
> >> > if (PTR_ERR(entry) == -EBUSY)
> >> > return VM_FAULT_NOPAGE;
> >> >
> >> > return VM_FAULT_SIGBUS;
> >> > }
> >> >
> >> > Not sure if those should be re-ordered that would keep the process
> >> stuck up
> >> > until there is something to reclaim. Now we use NOPAGE to address
> >> situation
> >> > when there is actually something to reclaim but because of locking
> >> side of
> >> > things we pass reclaim=false to sgx_alloc_epc_page().
> >> >
> >> > So this is kind of OOM behaviour how it works now instead of
> >> > stalling processes.
> >>
> >> Right, I looked at the original email at was really a page fault that
> >> was catched. The above theory cannot possibly hold, as the process
> >> does not exit with a bus error.
> >>
> >> I looked next to sgx_encl_eaug_page(), and found this:
> >>
> >> encl_page = sgx_encl_page_alloc(encl, addr - encl->base,
> >> secinfo_flags);
> >> if (IS_ERR(encl_page))
> >> return VM_FAULT_OOM;
> >>
> >> This is AFAIK the only code path in sgx_vma_fault() flow that
> >> allocates non-EPC memory, and the code paths where EPC allocation
> >> fails the result would be SIGBUS.
> >>
> >> So perhaps allocation is failing here. You could pretty easily trace
> >> allocations with bpftrace and kretprobe to see if this is what is
> >> happening, e.g. in one terminal:
> >>
> >> sudo bpftrace -e 'kr:sgx_encl_page_alloc /retval != 0/ {
> >> printf("%d\n", retval); }'
> >
> > Should be
> >
> > sudo bpftrace -e 'kr:sgx_encl_page_alloc /(long)retval < 0/ {
> > printf("%d\n", retval); }'
> >
> > BR, Jarkko
>
> I tried these probs and got following results when failure happens (not
> always happen on my device).
>
> sudo bpftrace -e 'kr:sgx_encl_page_alloc /(int64)retval <0 / { printf("%X\n",
> retval); }'
>
> --> lots of negative values, I believe they are valid addresses in
> unsigned long type. So I looked up IS_ERR_VALUE macro and translated it in
> following probes.
>
> sudo bpftrace -e 'kr:sgx_encl_page_alloc /(uint64)retval >= (uint64)(-4095)/ {
> printf("%X\n", retval); }'
>
> --> none triggered
>
> sudo bpftrace -e 'kr:sgx_alloc_epc_page /(uint64)retval >= (uint64)(-4095)/ {
> printf("%X\n", retval); }'
>
> --> FFFFFFF0 printed, which I believe is -EBUSY.
>
> BR
> Haitao
I see the same behavior as Haitao.
sudo bpftrace -e 'kr:sgx_encl_page_alloc /(long)retval < 0/ { printf("%d\n", retval); } -> This one gave an error stdin:1:24-31: ERROR: Unknown struct/union: 'long'
So switched to sudo bpftrace -e 'kr:sgx_encl_page_alloc /(int64)retval <0 / { printf("%X\n", retval); }' as suggested by Haitao and do see lot of positive and negative values.
sudo bpftrace -e 'kr:sgx_encl_page_alloc /(uint64)retval >= (uint64)(-4095)/ { printf("%X\n", retval); }' -> No output.
sudo bpftrace -e 'kr:sgx_alloc_epc_page /(uint64)retval >= (uint64)(-4095)/ { printf("%X\n", retval); } -> FFFFFFF0 is printed.
Thanks, Vijay
