Re: [PATCH 15/16] intel_l3_parity: Support error injection

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Sep 12, 2013 at 10:28:41PM -0700, Ben Widawsky wrote:
> Haswell added the ability to inject errors which is extremely useful for
> testing. Add two arguments to the tool to inject, and uninject.
> 
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>

Do we run any risk that a concurrent write/read to the same register range
could hang the machine due to the same-cacheline w/a we need? Just want to
make sure that when we integrate this into a testcase there's no surprises
like with intel_gpu_top ...
-Daniel

> ---
>  tests/sysfs_l3_parity   |  2 +-
>  tools/intel_l3_parity.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 68 insertions(+), 3 deletions(-)
> 
> diff --git a/tests/sysfs_l3_parity b/tests/sysfs_l3_parity
> index a0dfad9..e9d4411 100755
> --- a/tests/sysfs_l3_parity
> +++ b/tests/sysfs_l3_parity
> @@ -21,7 +21,7 @@ fi
>  $SOURCE_DIR/../tools/intel_l3_parity -r 0 -b 0 -s 0 -e
>  
>  #Check that we can clear remaps
> -if [ `$SOURCE_DIR/../tools/intel_l3_parity -l | wc -c` != "0" ] ; then
> +if [ `$SOURCE_DIR/../tools/intel_l3_parity -l | wc -l` != 1 ] ; then
>  	echo "Fail 2"
>  	exit 1
>  fi
> diff --git a/tools/intel_l3_parity.c b/tools/intel_l3_parity.c
> index cf15541..cd6754e 100644
> --- a/tools/intel_l3_parity.c
> +++ b/tools/intel_l3_parity.c
> @@ -79,6 +79,20 @@ static int which_slice = -1;
>  			(__i) < ((which_slice == -1) ? MAX_SLICES : (which_slice + 1)); \
>  			(__i)++)
>  
> +static void decode_dft(uint32_t dft)
> +{
> +	if (IS_IVYBRIDGE(devid) || !(dft & 1)) {
> +		printf("Error injection disabled\n");
> +		return;
> +	}
> +	printf("Error injection enabled\n");
> +	printf("  Hang = %s\n", (dft >> 28) & 0x1 ? "yes" : "no");
> +	printf("  Row = %d\n", (dft >> 7) & 0x7ff);
> +	printf("  Bank = %d\n", (dft >> 2) & 0x3);
> +	printf("  Subbank = %d\n", (dft >> 4) & 0x7);
> +	printf("  Slice = %d\n", (dft >> 1) & 0x1);
> +}
> +
>  static void dumpit(int slice)
>  {
>  	int i, j;
> @@ -150,7 +164,9 @@ static void usage(const char *name)
>  		"  -l, --list				List the current L3 logs\n"
>  		"  -a, --clear-all			Clear all disabled rows\n"
>  		"  -e, --enable				Enable row, bank, subbank (undo -d)\n"
> -		"  -d, --disable=<row,bank,subbank>	Disable row, bank, subbank (inline arguments are deprecated. Please use -r, -b, -s instead\n",
> +		"  -d, --disable=<row,bank,subbank>	Disable row, bank, subbank (inline arguments are deprecated. Please use -r, -b, -s instead\n"
> +		"  -i, --inject				[HSW only] Cause hardware to inject a row errors\n"
> +		"  -u, --uninject			[HSW only] Turn off hardware error injectection (undo -i)\n",
>  		name);
>  }
>  
> @@ -158,6 +174,7 @@ int main(int argc, char *argv[])
>  {
>  	const int device = drm_get_card();
>  	char *path[REAL_MAX_SLICES];
> +	uint32_t dft;
>  	int row = 0, bank = 0, sbank = 0;
>  	int fd[REAL_MAX_SLICES] = {0}, ret, i;
>  	int action = '0';
> @@ -167,6 +184,8 @@ int main(int argc, char *argv[])
>  	if (intel_gen(devid) < 7)
>  		exit(EXIT_SUCCESS);
>  
> +	assert(intel_register_access_init(intel_get_pci_device(), 0) == 0);
> +
>  	ret = asprintf(&path[0], "/sys/class/drm/card%d/l3_parity", device);
>  	assert(ret != -1);
>  	ret = asprintf(&path[1], "/sys/class/drm/card%d/l3_parity_slice_1", device);
> @@ -183,6 +202,7 @@ int main(int argc, char *argv[])
>  		assert(lseek(fd[i], 0, SEEK_SET) == 0);
>  	}
>  
> +	dft = intel_register_read(0xb038);
>  
>  	while (1) {
>  		int c, option_index = 0;
> @@ -192,6 +212,8 @@ int main(int argc, char *argv[])
>  			{ "clear-all", no_argument, 0, 'a' },
>  			{ "enable", no_argument, 0, 'e' },
>  			{ "disable", optional_argument, 0, 'd' },
> +			{ "inject", no_argument, 0, 'i' },
> +			{ "uninject", no_argument, 0, 'u' },
>  			{ "hw-info", no_argument, 0, 'H' },
>  			{ "row", required_argument, 0, 'r' },
>  			{ "bank", required_argument, 0, 'b' },
> @@ -200,7 +222,7 @@ int main(int argc, char *argv[])
>  			{0, 0, 0, 0}
>  		};
>  
> -		c = getopt_long(argc, argv, "hHr:b:s:w:aled::", long_options,
> +		c = getopt_long(argc, argv, "hHr:b:s:w:aled::iu", long_options,
>  				&option_index);
>  		if (c == -1)
>  			break;
> @@ -215,6 +237,7 @@ int main(int argc, char *argv[])
>  				printf("Number of banks: %d\n", num_banks());
>  				printf("Subbanks per bank: %d\n", NUM_SUBBANKS);
>  				printf("Max L3 size: %dK\n", L3_SIZE >> 10);
> +				printf("Has error injection: %s\n", IS_HASWELL(devid) ? "yes" : "no");
>  				exit(EXIT_SUCCESS);
>  			case 'r':
>  				row = atoi(optarg);
> @@ -236,6 +259,12 @@ int main(int argc, char *argv[])
>  				if (which_slice >= MAX_SLICES)
>  					exit(EXIT_FAILURE);
>  				break;
> +			case 'i':
> +			case 'u':
> +				if (!IS_HASWELL(devid)) {
> +					fprintf(stderr, "Error injection supported on HSW+ only\n");
> +					exit(EXIT_FAILURE);
> +				}
>  			case 'd':
>  				if (optarg) {
>  					ret = sscanf(optarg, "%d,%d,%d", &row, &bank, &sbank);
> @@ -256,6 +285,23 @@ int main(int argc, char *argv[])
>  		}
>  	}
>  
> +	if (action == 'i') {
> +		if (((dft >> 1) & 1) != which_slice) {
> +			fprintf(stderr, "DFT register already has slice %d enabled, and we don't support multiple slices. Try modifying -w; but sometimes the register sticks in the wrong way\n", (dft >> 1) & 1);
> +			exit(EXIT_FAILURE);
> +		}
> +
> +		if (which_slice == -1) {
> +			fprintf(stderr, "Cannot inject errors to multiple slices (modify -w)\n");
> +			exit(EXIT_FAILURE);
> +		}
> +		if (dft & 1 && ((dft >> 1) && 1) == which_slice)
> +			printf("warning: overwriting existing injections. This is very dangerous.\n");
> +	}
> +
> +	if (action == 'l')
> +		decode_dft(dft);
> +
>  	/* Per slice operations */
>  	for_each_slice(i) {
>  		switch (action) {
> @@ -271,11 +317,30 @@ int main(int argc, char *argv[])
>  			case 'd':
>  				assert(disable_rbs(row, bank, sbank, i) == 0);
>  				break;
> +			case 'i':
> +				if (bank == 3) {
> +					fprintf(stderr, "The hardware does not support error inject on bank 3.\n");
> +					exit(EXIT_FAILURE);
> +				}
> +				dft |= row << 7;
> +				dft |= sbank << 4;
> +				dft |= bank << 2;
> +				assert(i < 2);
> +				dft |= i << 1; /* slice */
> +				dft |= 1 << 0; /* enable */
> +				intel_register_write(0xb038, dft);
> +				break;
> +			case 'u':
> +				intel_register_write(0xb038, dft & ~(1<<0));
> +				break;
> +			case 'L':
> +				break;
>  			default:
>  				abort();
>  		}
>  	}
>  
> +	intel_register_access_fini();
>  	if (action == 'l')
>  		exit(EXIT_SUCCESS);
>  
> -- 
> 1.8.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch