Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965105AbVIVHw7 (ORCPT ); Thu, 22 Sep 2005 03:52:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932154AbVIVHtg (ORCPT ); Thu, 22 Sep 2005 03:49:36 -0400 Received: from mailout1.vmware.com ([65.113.40.130]:38917 "EHLO mailout1.vmware.com") by vger.kernel.org with ESMTP id S1751446AbVIVHtY (ORCPT ); Thu, 22 Sep 2005 03:49:24 -0400 Date: Thu, 22 Sep 2005 00:49:18 -0700 Message-Id: <200509220749.j8M7nINV001001@zach-dev.vmware.com> Subject: [PATCH 3/3] Gdt page isolation From: Zachary Amsden To: Linus Torvalds , Jeffrey Sheldon , Ole Agesen , Shai Fultheim , Andrew Morton , Jack Lo , Ingo Molnar , Linux Kernel Mailing List , Virtualization Mailing List , Chris Wright , Martin Bligh , Pratap Subrahmanyam , Christopher Li , "H. Peter Anvin" , Zwane Mwaikambo , Andi Kleen , Zachary Amsden X-OriginalArrivalTime: 22 Sep 2005 07:49:20.0726 (UTC) FILETIME=[244A4760:01C5BF4A] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3847 Lines: 88 Make GDT page aligned and page padded to support running inside of a hypervisor. This prevents false sharing of the GDT page with other hot data, which is not allowed in Xen, and causes performance problems in VMware. Rather than go back to the old method of statically allocating the GDT (which wastes unneded space for non-present CPUs), the GDT for APs is allocated dynamically. Signed-off-by: Zachary Amsden Index: linux-2.6.14-rc1/include/asm-i386/desc.h =================================================================== --- linux-2.6.14-rc1.orig/include/asm-i386/desc.h 2005-09-20 20:19:57.000000000 -0700 +++ linux-2.6.14-rc1/include/asm-i386/desc.h 2005-09-20 20:20:50.000000000 -0700 @@ -15,9 +15,6 @@ #include extern struct desc_struct cpu_gdt_table[GDT_ENTRIES]; -DECLARE_PER_CPU(struct desc_struct, cpu_gdt_table[GDT_ENTRIES]); - -#define get_cpu_gdt_table(_cpu) (per_cpu(cpu_gdt_table,_cpu)) DECLARE_PER_CPU(unsigned char, cpu_16bit_stack[CPU_16BIT_STACK_SIZE]); @@ -29,6 +26,8 @@ struct Xgt_desc_struct { extern struct Xgt_desc_struct idt_descr, cpu_gdt_descr[NR_CPUS]; +#define get_cpu_gdt_table(_cpu) ((struct desc_struct *)cpu_gdt_descr[(_cpu)].address) + #define load_TR_desc() __asm__ __volatile__("ltr %w0"::"q" (GDT_ENTRY_TSS*8)) #define load_LDT_desc() __asm__ __volatile__("lldt %w0"::"q" (GDT_ENTRY_LDT*8)) Index: linux-2.6.14-rc1/arch/i386/kernel/i386_ksyms.c =================================================================== --- linux-2.6.14-rc1.orig/arch/i386/kernel/i386_ksyms.c 2005-09-20 20:19:57.000000000 -0700 +++ linux-2.6.14-rc1/arch/i386/kernel/i386_ksyms.c 2005-09-20 20:28:51.000000000 -0700 @@ -3,8 +3,7 @@ #include #include -/* This is definitely a GPL-only symbol */ -EXPORT_SYMBOL_GPL(cpu_gdt_table); +EXPORT_SYMBOL_GPL(cpu_gdt_descr); EXPORT_SYMBOL(__down_failed); EXPORT_SYMBOL(__down_failed_interruptible); Index: linux-2.6.14-rc1/arch/i386/kernel/smpboot.c =================================================================== --- linux-2.6.14-rc1.orig/arch/i386/kernel/smpboot.c 2005-09-20 20:19:57.000000000 -0700 +++ linux-2.6.14-rc1/arch/i386/kernel/smpboot.c 2005-09-20 20:38:22.000000000 -0700 @@ -898,6 +898,7 @@ static int __devinit do_boot_cpu(int api * This grunge runs the startup process for * the targeted processor. */ + cpu_gdt_descr[cpu].address = __get_free_page(GFP_KERNEL|__GFP_ZERO); atomic_set(&init_deasserted, 0); Index: linux-2.6.14-rc1/arch/i386/kernel/head.S =================================================================== --- linux-2.6.14-rc1.orig/arch/i386/kernel/head.S 2005-09-20 14:32:16.000000000 -0700 +++ linux-2.6.14-rc1/arch/i386/kernel/head.S 2005-09-20 20:44:38.000000000 -0700 @@ -525,3 +525,5 @@ ENTRY(cpu_gdt_table) .quad 0x0000000000000000 /* 0xf0 - unused */ .quad 0x0000000000000000 /* 0xf8 - GDT entry 31: double-fault TSS */ + /* Be sure this is zeroed to avoid false validations in Xen */ + .fill PAGE_SIZE_asm / 8 - GDT_ENTRIES,8,0 Index: linux-2.6.14-rc1/arch/i386/kernel/cpu/common.c =================================================================== --- linux-2.6.14-rc1.orig/arch/i386/kernel/cpu/common.c 2005-09-20 20:19:57.000000000 -0700 +++ linux-2.6.14-rc1/arch/i386/kernel/cpu/common.c 2005-09-20 20:37:31.000000000 -0700 @@ -18,9 +18,6 @@ #include "cpu.h" -DEFINE_PER_CPU(struct desc_struct, cpu_gdt_table[GDT_ENTRIES]); -EXPORT_PER_CPU_SYMBOL(cpu_gdt_table); - DEFINE_PER_CPU(unsigned char, cpu_16bit_stack[CPU_16BIT_STACK_SIZE]); EXPORT_PER_CPU_SYMBOL(cpu_16bit_stack); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/