[igt-dev] [PATCH v1] tools/intel_gtt: stop confusing GTT and BAR sizes

[Kamil Konieczny]

Hi Daniil,

On 2022-11-18 at 01:59:07 +0300, Daniil Tatianin wrote:
> The GTT iteration loop would erroneously check "< gtt_size" as an
> indicator for when it should stop, which would make it exit the loop
> right after dumping 2-8 mib of address space depending on the
> GPU generation.
> 
> Calculate the actual size of GTT in 'gtt_max_addr', and rewrite the
> iteration loop to use it. While at it, also make virtual addresses
> 64-bit so that they don't wrap around at the 4GiB mark.
> 
> Signed-off-by: Daniil Tatianin <99danilt at gmail.com>

There is only one concern - this programm assumes 4KB page size
and uses unsigned instead of unsigned int (or uint64_t).

Reviewed-by: Kamil Konieczny <kamil.konieczny at linux.intel.com>

> ---
>  tools/intel_gtt.c | 32 ++++++++++++++++++--------------
>  1 file changed, 18 insertions(+), 14 deletions(-)
> 
> diff --git a/tools/intel_gtt.c b/tools/intel_gtt.c
> index 311694ba..c0f3d16a 100644
> --- a/tools/intel_gtt.c
> +++ b/tools/intel_gtt.c
> @@ -96,6 +96,11 @@ static uint64_t get_phys(uint32_t pt_offset)
>  	return (phys | pae) & ~0xfff;
>  }
> 
> +static int get_pte_size(void)
> +{
> +	return intel_gen(devid) < 8 ? 4 : 8;
> +}
> +
>  static void pte_dump(int size, uint32_t offset) {
>  	int pte_size;
>  	int entries;
> @@ -105,11 +110,7 @@ static void pte_dump(int size, uint32_t offset) {
>  	if (size % 16)
>  		size = (size + 16) & ~0xffff;
> 
> -	if (intel_gen(devid) < 8)
> -		pte_size = 4;
> -	else
> -		pte_size = 8;
> -
> +	pte_size = get_pte_size();
>  	entries = size / pte_size;
> 
>  	printf("GTT offset   |                 %d PTEs (%d MB)\n", entries,
> @@ -139,7 +140,8 @@ static void pte_dump(int size, uint32_t offset) {
>  int main(int argc, char **argv)
>  {
>  	struct pci_device *pci_dev;
> -	unsigned int start, gtt_size;
> +	unsigned gtt_size;
> +	uint64_t start, gtt_max_addr;
>  	int flag[] = {
>  		PCI_DEV_MAP_FLAG_WRITE_COMBINE,
>  		PCI_DEV_MAP_FLAG_WRITABLE,
> @@ -190,14 +192,15 @@ int main(int argc, char **argv)
>  		return 0;
>  	}
> 
> -	for (start = 0; start < gtt_size; start += KB(4)) {
> -		uint64_t start_phys = get_phys(start);
> -		uint32_t end;
> +	gtt_max_addr = (gtt_size / get_pte_size()) * KB(4ull);
> +
> +	for (start = 0; start < gtt_max_addr; start += KB(4)) {
> +		uint64_t end, start_phys = get_phys(start);
>  		int constant_length = 0;
>  		int linear_length = 0;
> 
>  		/* Check if it's a linear sequence */
> -		for (end = start + KB(4); end < gtt_size; end += KB(4)) {
> +		for (end = start + KB(4); end < gtt_max_addr; end += KB(4)) {
>  			uint64_t end_phys = get_phys(end);
>  			if (end_phys == start_phys + (end - start))
>  				linear_length++;
> @@ -205,7 +208,7 @@ int main(int argc, char **argv)
>  				break;
>  		}
>  		if (linear_length > 0) {
> -			printf("0x%08x - 0x%08x: linear from "
> +			printf("0x%08" PRIx64 "- 0x%08" PRIx64 ": linear from "
>  			       "0x%" PRIx64 " to 0x%" PRIx64 "\n",
>  			       start, end - KB(4),
>  			       start_phys, start_phys + (end - start) - KB(4));
> @@ -214,7 +217,7 @@ int main(int argc, char **argv)
>  		}
> 
>  		/* Check if it's a constant sequence */
> -		for (end = start + KB(4); end < gtt_size; end += KB(4)) {
> +		for (end = start + KB(4); end < gtt_max_addr; end += KB(4)) {
>  			uint64_t end_phys = get_phys(end);
>  			if (end_phys == start_phys)
>  				constant_length++;
> @@ -222,13 +225,14 @@ int main(int argc, char **argv)
>  				break;
>  		}
>  		if (constant_length > 0) {
> -			printf("0x%08x - 0x%08x: constant 0x%" PRIx64 "\n",
> +			printf("0x%08" PRIx64 " - 0x%08" PRIx64
> +				": constant 0x%" PRIx64 "\n",
>  			       start, end - KB(4), start_phys);
>  			start = end - KB(4);
>  			continue;
>  		}
> 
> -		printf("0x%08x: 0x%" PRIx64 "\n", start, start_phys);
> +		printf("0x%08" PRIx64 ": 0x%" PRIx64 "\n", start, start_phys);
>  	}
> 
>  	return 0;
> --
> 2.36.1.windows.1
>