On Tue 3/4/2014 8:59 AM, Joerg Roedel wrote
>On Fri, Jan 10, 2014 at 03:07:29PM -0700, Bill Sumner wrote:
>> +context_get_entry(struct context_entry *context_addr,
>> + struct intel_iommu *iommu, u32 bus, int devfn) {
>> + unsigned long long q; /* quadword scratch */
>> + struct root_entry *root_phys; /* Phys adr (root table entry) */
>> + struct root_entry root_temp; /* Local copy of root_entry */
>> + struct context_entry *context_phys; /* Phys adr */
>> +
>> + if (pr_dbg.domain_get)
>> + pr_debug("ENTER %s B:D:F=%2.2x:%2.2x:%1.1x &context_entry:0x%llx &intel_iommu:0x%llx\n",
>> + __func__, bus, devfn>>3, devfn&7,
>> + (u64)context_addr, (u64)iommu);
>> +
>> + if (bus > 255) /* Sanity check */
>> + return -5;
>> + if (devfn > 255 || devfn < 0) /* Sanity check */
>> + return -6;
>> +
>> + q = readq(iommu->reg + DMAR_RTADDR_REG);
>> + pr_debug("IOMMU %d: DMAR_RTADDR_REG:0x%16.16llx\n", iommu->seq_id, q);
>> + if (!q)
>> + return -1;
>> +
>> + root_phys = (struct root_entry *) q; /* Adr(base of vector) */
>> + root_phys += bus; /* Adr(entry we want) */
>> +
>> + oldcopy(&root_temp, root_phys, sizeof(root_temp));
>> +
>> + pr_debug("root_temp.val:0x%llx .rsvd1:0x%llx root_phys:0x%llx\n",
>> + root_temp.val, root_temp.rsvd1, (u64)root_phys);
>> +
>> + if (!root_present(&root_temp))
>> + return -2;
>> +
>> + pr_debug("B:D:F=%2.2x:%2.2x:%1.1x root_temp.val: %llx .rsvd1: %llx\n",
>> + bus, devfn >> 3, devfn & 7, root_temp.val, root_temp.rsvd1);
>> +
>> + if (root_temp.rsvd1) /* If (root_entry is bad) */
>> + return -3;
>> +
>> + context_phys = get_context_phys_from_root(&root_temp);
>> + if (!context_phys)
>> + return -4;
>
>What do all these magic return values mean?
They all mean "No value to return". The different negative values are an artifact of the development where I wanted to make it easy not only to tell that something went wrong, but also to have enough detail to figure-out what happened without having to add code and repeat the test. I will clean-up these in the next submission -- along with a few additional places where there are similar "leftovers".
Bill
