From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
Subject: Re: [PATCH v3] bus/pci: forbid VA as IOVA mode if IOMMU
 address width too small
Date: Fri, 12 Jan 2018 11:10:51 +0000
Message-ID: <89c16dd0-3938-f9ae-cc9f-189388abc0a9@intel.com>
References: <20180112102220.20061-1-maxime.coquelin@redhat.com>
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Cc: peterx@redhat.com
To: Maxime Coquelin <maxime.coquelin@redhat.com>, dev@dpdk.org,
 stable@dpdk.org, jianfeng.tan@intel.com, qi.z.zhang@intel.com,
 stephen@networkplumber.org, santosh.shukla@caviumnetworks.com,
 thomas@monjalon.net
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<snip>

> +#if defined(RTE_ARCH_X86)
> +static bool
> +pci_one_device_iommu_support_va(struct rte_pci_device *dev)
> +{
> +#define VTD_CAP_MGAW_SHIFT	16
> +#define VTD_CAP_MGAW_MASK	(0x3fULL << VTD_CAP_MGAW_SHIFT)
> +#define X86_VA_WIDTH 47 /* From Documentation/x86/x86_64/mm.txt */
> +	struct rte_pci_addr *addr = &dev->addr;
> +	char filename[PATH_MAX];
> +	FILE *fp;
> +	uint64_t mgaw, vtd_cap_reg = 0;
> +
> +	snprintf(filename, sizeof(filename),
> +		 "%s/" PCI_PRI_FMT "/iommu/intel-iommu/cap",
> +		 rte_pci_get_sysfs_path(), addr->domain, addr->bus, addr->devid,
> +		 addr->function);
> +	if (access(filename, F_OK) == -1) {
> +		/* We don't have an Intel IOMMU, assume VA supported*/
> +		return true;
> +	}
> +
> +	/* We have an intel IOMMU */
> +	fp = fopen(filename, "r");
> +	if (fp == NULL) {
> +		RTE_LOG(ERR, EAL, "%s(): can't open %s\n", __func__, filename);
> +		return false;
> +	}
> +
> +	if (fscanf(fp, "%lx", &vtd_cap_reg) != 1) {
> +		RTE_LOG(ERR, EAL, "%s(): can't read %s\n", __func__, filename);
> +		fclose(fp);
> +		return false;
> +	}
> +
> +	fclose(fp);

Hi Maxime,

You probably want to use eal_parse_sysfs_value() for this.


-- 
Thanks,
Anatoly