[dpdk-stable] [PATCH v3] bus/pci: forbid VA as IOVA mode if IOMMU address width too small
Maxime Coquelin
maxime.coquelin at redhat.com
Fri Jan 12 14:18:47 CET 2018
Hi Anatoly,
On 01/12/2018 12:10 PM, Burakov, Anatoly wrote:
> <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.
I initially planned to use it, but the sysfs value is hexadecimal, but
not prefixed with "0x". For example:
# cat /sys/devices/pci0000\:00/0000\:00\:02.0/iommu/intel-iommu/cap
1c0000c40660462
So strtoul() assumes the value is decimal in this case, as explained in
its man page:
"
DESCRIPTION
<snip\>
If base is zero or 16, the string may then include a "0x" prefix, and
the number will be read in base 16; otherwise, a zero base is taken as
10 (decimal)
"
Thanks,
Maxime
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