From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andre Przywara Subject: [PATCH] libxc: remove CPUID core information mangling Date: Wed, 25 Aug 2010 14:04:10 +0200 Message-ID: <4C7506BA.4000001@amd.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------060409040602090008030603" Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser , Nitin Kamble Cc: xen-devel List-Id: xen-devel@lists.xenproject.org --------------060409040602090008030603 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Hi, c/s 18560:782599274bf9ae8857c55856c9c7fdf082967808 introduced CPUID mangling resulting in a doubled number of cores/processor exposed to the guest. According to comments in this patch the rationale behind this is to match the APIC numbering used by Xen. In my understanding the CPUID leafs dealing with number of cores always talk about logical numbers and not APIC IDs. So we don't need to adjust the CPUID readout to match the APIC ID enumeration scheme. If there were any serious reasons resulting in the old patch I'd love to hear them. The attached patch fixes this and solves an issue I saw with certain NUMA guest configurations. Signed-off-by: Andre Przywara -- Andre Przywara AMD-Operating System Research Center (OSRC), Dresden, Germany Tel: +49 351 448-3567-12 --------------060409040602090008030603 Content-Type: text/x-patch; name="fix_cpuid_core_mangling.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="fix_cpuid_core_mangling.patch" diff -r eccfdeb41b80 tools/libxc/xc_cpuid_x86.c --- a/tools/libxc/xc_cpuid_x86.c Tue Aug 24 18:42:59 2010 +0100 +++ b/tools/libxc/xc_cpuid_x86.c Wed Aug 25 13:34:54 2010 +0200 @@ -117,9 +117,8 @@ case 0x80000008: /* * ECX[15:12] is ApicIdCoreSize: ECX[7:0] is NumberOfCores (minus one). - * Update to reflect vLAPIC_ID = vCPU_ID * 2. */ - regs[2] = ((regs[2] & 0xf000u) + 1) | ((regs[2] & 0xffu) << 1) | 1u; + regs[2] &= 0xf0ffu; break; } } @@ -134,11 +133,9 @@ case 0x00000004: /* * EAX[31:26] is Maximum Cores Per Package (minus one). - * Update to reflect vLAPIC_ID = vCPU_ID * 2. */ - regs[0] = (((regs[0] & 0x7c000000u) << 1) | 0x04000000u | - (regs[0] & 0x3ffu)); - regs[3] &= 0x3ffu; + regs[0] &= 0xfc0003ffu; + regs[3] &= 0x00000003u; break; case 0x80000001: { @@ -185,9 +182,8 @@ case 0x00000001: /* * EBX[23:16] is Maximum Logical Processors Per Package. - * Update to reflect vLAPIC_ID = vCPU_ID * 2. */ - regs[1] = (regs[1] & 0x0000ffffu) | ((regs[1] & 0x007f0000u) << 1); + regs[1] & 0x00ffffffu; regs[2] &= (bitmaskof(X86_FEATURE_XMM3) | bitmaskof(X86_FEATURE_SSSE3) | --------------060409040602090008030603 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel --------------060409040602090008030603--