Re: [PATCH v5] pci: read amd iommu virtual address width

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 13 Oct 2022 20:16:02 +0200
Michael Piszczek <mpiszczek@ddn.com> wrote:

> Add code to read the virtual address width for AMD processors.
> Updated pci_device_iommu_support_va() to use glob to find iommu
> capability files.
> 
> Signed-off-by: Michael Piszczek <mpiszczek@ddn.com>
> ---
>  drivers/bus/pci/linux/pci.c | 58 ++++++++++++++++++++++---------------
>  1 file changed, 35 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
> index ebd1395502..291090ba7b 100644
> --- a/drivers/bus/pci/linux/pci.c
> +++ b/drivers/bus/pci/linux/pci.c
> @@ -4,6 +4,7 @@
>  
>  #include <string.h>
>  #include <dirent.h>
> +#include <glob.h>
>  
>  #include <rte_log.h>
>  #include <rte_pci.h>
> @@ -480,42 +481,53 @@ rte_pci_scan(void)
>  }
>  
>  #if defined(RTE_ARCH_X86)
> +
>  bool
>  pci_device_iommu_support_va(const struct rte_pci_device *dev)
>  {
> -#define VTD_CAP_MGAW_SHIFT	16
> -#define VTD_CAP_MGAW_MASK	(0x3fULL << VTD_CAP_MGAW_SHIFT)
> +#define VTD_CAP_MGAW_SHIFT      16
> +#define VTD_CAP_MGAW_MASK       (0x3fULL << VTD_CAP_MGAW_SHIFT)
> +#define RD_AMD_CAP_VASIZE_SHIFT 15
> +#define RD_AMD_CAP_VASIZE_MASK  (0x7F << RD_AMD_CAP_VASIZE_SHIFT)
> +	int rc;
>  	const struct rte_pci_addr *addr = &dev->addr;
> -	char filename[PATH_MAX];
> -	FILE *fp;
> -	uint64_t mgaw, vtd_cap_reg = 0;
> +	char pattern[PATH_MAX];
> +	glob_t glob_results;
> +	uint64_t mgaw = 0;
>  
> -	snprintf(filename, sizeof(filename),
> -		 "%s/" PCI_PRI_FMT "/iommu/intel-iommu/cap",
> +	snprintf(pattern, sizeof(pattern),
> +		 "%s/" PCI_PRI_FMT "/iommu/*-iommu/cap",
>  		 rte_pci_get_sysfs_path(), addr->domain, addr->bus, addr->devid,
>  		 addr->function);
>  
> -	fp = fopen(filename, "r");
> -	if (fp == NULL) {
> -		/* We don't have an Intel IOMMU, assume VA supported */
> -		if (errno == ENOENT)
> -			return true;
> +	rc = glob(pattern, 0, NULL, &glob_results);
> +	if (rc != 0 && glob_results.gl_pathc == 1) {
> +		const char *filename = glob_results.gl_pathv[0];

Why not use fnmatch() instead of glob()?
Most of the places in DPDK use that to do this kind of matching.