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

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Message-ID: <YzdjMeEjflRgfkdD@kernel.org>
Date:   Sat, 1 Oct 2022 00:44:17 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Thomas Tai <thomas.tai@...cle.com>
Cc:     tony.luck@...el.com, dave.hansen@...ux.intel.com,
        reinette.chatre@...el.co, naoya.horiguchi@....com,
        linmiaohe@...wei.com, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/sgx: Add code to inject hwpoison into SGX memory

On Tue, Sep 27, 2022 at 02:34:11PM -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>
> ---
>  Documentation/mm/hwpoison.rst | 44 +++++++++++++++++++++++++++++++++++
>  mm/hwpoison-inject.c          |  3 +++
>  2 files changed, 47 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
> +
>  References
>  ==========
>  
> diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
> index 65e242b5a432..8134dc983699 100644
> --- a/mm/hwpoison-inject.c
> +++ b/mm/hwpoison-inject.c
> @@ -21,6 +21,9 @@ static int hwpoison_inject(void *data, u64 val)
>  	if (!capable(CAP_SYS_ADMIN))
>  		return -EPERM;
>  
> +	if (arch_is_platform_page(pfn << PAGE_SHIFT))
> +		goto inject;
> +
>  	if (!pfn_valid(pfn))
>  		return -ENXIO;
>  
> -- 
> 2.31.1
> 

Hey, this is really useful addition. Thanks for doing this.

Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>

BR, Jarkko