On 20/09/2019 14:54, Jan Beulich wrote: > @@ -395,11 +395,20 @@ static void amd_xc_cpuid_policy(const st > > case 0x80000008: > /* > - * ECX[15:12] is ApicIdCoreSize: ECX[7:0] is NumberOfCores (minus > one). > - * Update to reflect vLAPIC_ID = vCPU_ID * 2. > + * ECX[15:12] is ApicIdCoreSize. > + * ECX[7:0] is NumberOfCores (minus one). > + * Update to reflect vLAPIC_ID = vCPU_ID * 2. But make sure to avoid > + * - overflow, > + * - going out of sync with leaf 1 EBX[23:16], > + * - incrementing ApicIdCoreSize when it's zero (which changes the > + * meaning of bits 7:0). > */ > - regs[2] = ((regs[2] + (1u << 12)) & 0xf000u) | > - ((regs[2] & 0xffu) << 1) | 1u; > + if ( (regs[2] & 0x7fu) < 0x7fu )
In attempting to rebase my series, there is a bug here. It should be & 0xff otherwise the top bit isn't included in the comparison, and a value of 128 will still be doubled. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
