On 5/19/22 12:27, Suravee Suthikulpanit wrote:
+ * If the x2APIC logical ID sub-field (i.e. icrh[15:0]) contains zero + * or more than 1 bits, we cannot match just one vcpu to kick for + * fast path. + */ + if (!first || (first != last)) + return -EINVAL; + + apic = first - 1; + if ((apic < 0) || (apic > 15) || (cluster >= 0xfffff)) + return -EINVAL;
Neither of these is possible: first == 0 has been cheked above, and ffs(icrh & 0xffff) cannot exceed 15. Likewise, cluster is actually limited to 16 bits, not 20. Plus, C is not Pascal so no parentheses. :) Putting everything together, it can be simplified to this: + int cluster = (icrh & 0xffff0000) >> 16; + int apic = ffs(icrh & 0xffff) - 1; + + /* + * If the x2APIC logical ID sub-field (i.e. icrh[15:0]) + * contains anything but a single bit, we cannot use the + * fast path, because it is limited to a single vCPU. + */ + if (apic < 0 || icrh != (1 << apic)) + return -EINVAL; + + l1_physical_id = (cluster << 4) + apic;
+ apic_id = (cluster << 4) + apic;
