linux-kernel - Re: [PATCH V2 1/1] x86/sgx: Add code to inject hwpoison into SGX memory

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Date:   Fri, 7 Oct 2022 06:33:43 +0000
From:   HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>
To:     Thomas Tai <thomas.tai@...cle.com>
CC:     "tony.luck@...el.com" <tony.luck@...el.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "jarkko@...nel.org" <jarkko@...nel.org>,
        "reinette.chatre@...el.co" <reinette.chatre@...el.co>,
        "linmiaohe@...wei.com" <linmiaohe@...wei.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
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@...cle.com>

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.

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