similar to: proposed interface change for setting the ldt

Hi, this is a series of patches that unify the struct desc_struct and friends across x86_64 and i386. As usual, it provides paravirt capabilities as a side-effect for x86_64. I consider the main goal, namely, of unifying the desc_struct, an ongoing effort, being this the beginning. A lot of old code has to be touched to accomplish that. I don't consider this patch ready for inclusion.

Hi, this is a series of patches that unify the struct desc_struct and friends across x86_64 and i386. As usual, it provides paravirt capabilities as a side-effect for x86_64. I consider the main goal, namely, of unifying the desc_struct, an ongoing effort, being this the beginning. A lot of old code has to be touched to accomplish that. I don't consider this patch ready for inclusion.

Descriptor and trap table cleanups. Add cleanly written accessors for IDT and GDT gates so the subarch may override them. Note that this allows the hypervisor to transparently tweak the DPL of the descriptors as well as the RPL of segments in those descriptors, with no unnecessary kernel code modification. It also allows the hypervisor implementation of the VMI to tweak the gates, allowing for

Descriptor and trap table cleanups. Add cleanly written accessors for IDT and GDT gates so the subarch may override them. Note that this allows the hypervisor to transparently tweak the DPL of the descriptors as well as the RPL of segments in those descriptors, with no unnecessary kernel code modification. It also allows the hypervisor implementation of the VMI to tweak the gates, allowing for

(Andrew, please sit these in the -mm tree for cooking) Create a paravirt.h header for (almost) all the critical operations which need to be replaced with hypervisor calls. For the moment, this simply includes no_paravirt.h, where all the native implementations now live. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Zachary Amsden <zach@vmware.com>

(Andrew, please sit these in the -mm tree for cooking) Create a paravirt.h header for (almost) all the critical operations which need to be replaced with hypervisor calls. For the moment, this simply includes no_paravirt.h, where all the native implementations now live. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Zachary Amsden <zach@vmware.com>

plain text document attachment (xx-paravirt-desc-header.patch) Update the descriptors for an interface with paravirt ops Signed-off-by: Steven Rostedt srostedt@redhat.com Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> Index: clean-start/include/asm-x86_64/desc.h =================================================================== ---

plain text document attachment (xx-paravirt-desc-header.patch) Update the descriptors for an interface with paravirt ops Signed-off-by: Steven Rostedt srostedt@redhat.com Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> Index: clean-start/include/asm-x86_64/desc.h =================================================================== ---

Chris Wright wrote: >* Zachary Amsden (zach@vmware.com) wrote: > > >>Does Xen assume page aligned descriptor tables? I assume from this >> >> > >Yes. > > > >>patch and snippets I have gathered from others, that is a yes, and other >>things here imply that DT pages are not shadowed. If so, Xen itself >>must have live segments

Chris Wright wrote: >* Zachary Amsden (zach@vmware.com) wrote: > > >>Does Xen assume page aligned descriptor tables? I assume from this >> >> > >Yes. > > > >>patch and snippets I have gathered from others, that is a yes, and other >>things here imply that DT pages are not shadowed. If so, Xen itself >>must have live segments

Introduce a write acessor for updating the current LDT. This is required for hypervisors like Xen that do not allow LDT pages to be directly written. Testing - here's a fun little LDT test that can be trivially modified to test limits as well. /* * Copyright (c) 2005, Zachary Amsden (zach@vmware.com) * This is licensed under the GPL. */ #include <stdio.h> #include <signal.h>

Introduce a write acessor for updating the current LDT. This is required for hypervisors like Xen that do not allow LDT pages to be directly written. Testing - here's a fun little LDT test that can be trivially modified to test limits as well. /* * Copyright (c) 2005, Zachary Amsden (zach@vmware.com) * This is licensed under the GPL. */ #include <stdio.h> #include <signal.h>

Add an acessor function to get a pointer to an LDT descriptor. Add one for the GDT too, while we are here, and a function to tell the difference. Turns out on some GCC versions, converting to char * and back gives better code output than gdt[seg >> 3]. Lets keep that trick in the header file so the C-code can be clean. Not used yet, but soon. Signed-off-by: Zachary Amsden

Add an acessor function to get a pointer to an LDT descriptor. Add one for the GDT too, while we are here, and a function to tell the difference. Turns out on some GCC versions, converting to char * and back gives better code output than gdt[seg >> 3]. Lets keep that trick in the header file so the C-code can be clean. Not used yet, but soon. Signed-off-by: Zachary Amsden

i386 Transparent paravirtualization subarch patch #5 This change encapsulates descriptor and task register management. Diffs against: 2.6.13-rc4-mm1 Signed-off-by: Zachary Amsden <zach@vmware.com> Index: linux-2.6.13/include/asm-i386/desc.h =================================================================== --- linux-2.6.13.orig/include/asm-i386/desc.h 2005-08-08 17:31:59.000000000 -0700

i386 Transparent paravirtualization subarch patch #5 This change encapsulates descriptor and task register management. Diffs against: 2.6.13-rc4-mm1 Signed-off-by: Zachary Amsden <zach@vmware.com> Index: linux-2.6.13/include/asm-i386/desc.h =================================================================== --- linux-2.6.13.orig/include/asm-i386/desc.h 2005-08-08 17:31:59.000000000 -0700

By Andi Kleen's suggestion, this patch removes pack_ldt() and pack_tss() wrappers in favour of a general wrapper. It saves us an ifdef and some lines of code, but more importantly, it's more elegant. No functional change is made. Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> --- include/asm-x86/desc.h | 55 ++++++++++++++--------------------------------- 1 files

By Andi Kleen's suggestion, this patch removes pack_ldt() and pack_tss() wrappers in favour of a general wrapper. It saves us an ifdef and some lines of code, but more importantly, it's more elegant. No functional change is made. Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> --- include/asm-x86/desc.h | 55 ++++++++++++++--------------------------------- 1 files

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:

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: