RE: [PATCH V2 1/1] x86/sgx: Add code to inject hwpoison into SGX memory

[Thomas Tai]

> -----Original Message-----
> From: HORIGUCHI NAOYA(堀口　直也) <naoya.horiguchi@xxxxxxx>
> Sent: October 7, 2022 2:34 AM
> To: Thomas Tai <thomas.tai@xxxxxxxxxx>
> Cc: tony.luck@xxxxxxxxx; dave.hansen@xxxxxxxxxxxxxxx; jarkko@xxxxxxxxxx;
> reinette.chatre@xxxxxxxx; linmiaohe@xxxxxxxxxx; akpm@linux-
> foundation.org; linux-mm@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH V2 1/1] x86/sgx: Add code to inject hwpoison into SGX
> memory
> 
> On Wed, Sep 28, 2022 at 11:38:32AM -0400, Thomas Tai wrote:
> > Inspired by commit c6acb1e7bf46 (x86/sgx: Add hook to error injection
> > address validation), add a similar code in hwpoison_inject function to
> > check if the address is located in SGX Memory. The error will then be
> > handled by the arch_memory_failure function in the SGX driver.
> >
> > Signed-off-by: Thomas Tai <thomas.tai@xxxxxxxxxx>
> 
> Thank you for sending patch.
> 
> > ---
> >  Documentation/mm/hwpoison.rst | 44
> +++++++++++++++++++++++++++++++++++
> >  mm/hwpoison-inject.c          |  4 ++++
> >  2 files changed, 48 insertions(+)
> >
> > diff --git a/Documentation/mm/hwpoison.rst
> b/Documentation/mm/hwpoison.rst
> > index b9d5253c1305..8a542aca4744 100644
> > --- a/Documentation/mm/hwpoison.rst
> > +++ b/Documentation/mm/hwpoison.rst
> > @@ -162,6 +162,50 @@ Testing
> >
> >    Some portable hwpoison test programs in mce-test, see below.
> >
> > +* Special notes for injection into SGX enclaves
> > +
> > +  1) Determine physical address of enclave page
> > +
> > +	dmesg | grep "sgx: EPC"
> > +
> > +	sgx: EPC section 0x8000c00000-0x807f7fffff
> > +	sgx: EPC section 0x10000c00000-0x1007fffffff
> > +
> > +  2) Convert the EPC address to page frame number.
> > +
> > +	For 4K page size, the page frame number for 0x8000c00000 is
> > +	0x8000c00000 / 0x1000 = 0x8000c00.
> > +
> > +  3) Trace memory_failure
> > +
> > +	echo nop > /sys/kernel/tracing/current_tracer
> > +	echo *memory_failure > /sys/kernel/tracing/set_ftrace_filter
> > +	echo function > /sys/kernel/tracing/current_tracer
> > +
> > +  4) Inject a memory error
> > +
> > +	modprobe hwpoison-inject
> > +	echo "0x8000c00" > /sys/kernel/debug/hwpoison/corrupt-pfn
> > +
> > +  5) Check the trace output
> > +
> > +	cat /sys/kernel/tracing/trace
> > +
> > +	# tracer: function
> > +	#
> > +	# entries-in-buffer/entries-written: 2/2   #P:128
> > +	#
> > +	#                            _-----=> irqs-off
> > +	#                           / _----=> need-resched
> > +	#                          | / _---=> hardirq/softirq
> > +	#                          || / _--=> preempt-depth
> > +	#                          ||| / _-=> migrate-disable
> > +	#                          |||| /     delay
> > +	#       TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> > +	#          | |         |   |||||     |         |
> > +	        bash-12167   [002] .....   113.136808: memory_failure<-
> simple_attr_write
> > +	        bash-12167   [002] .....   113.136810: arch_memory_failure<-
> memory_failure
> 
> In other cases of page types, memory_failure() leaves some kernel message
> like "Memory failure: 0x10cf09: recovery action for free buddy page:
> Recovered",
> which is printed out by action_result().  So I think it's better to adjust to
> this convention also in SGX page's case.  Then, you don't have to use ftrace
> to confirm the result of error injection.

Hi Naoya,
Thanks for your suggestion, I will look into it.

Thomas

> 
> Thanks,
> Naoya Horiguchi
> 
> > +
> >  References
> >  ==========
> >
> > diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
> > index 65e242b5a432..bf83111c1d9b 100644
> > --- a/mm/hwpoison-inject.c
> > +++ b/mm/hwpoison-inject.c
> > @@ -21,6 +21,10 @@ static int hwpoison_inject(void *data, u64 val)
> >  	if (!capable(CAP_SYS_ADMIN))
> >  		return -EPERM;
> >
> > +	/* Inject the error if the page is part of the processor reserved memory
> */
> > +	if (arch_is_platform_page(pfn << PAGE_SHIFT))
> > +		goto inject;
> > +
> >  	if (!pfn_valid(pfn))
> >  		return -ENXIO;
> >
> > --
> > 2.31.1