- 20 7月, 2007 10 次提交
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由 Dave Jiang 提交于
Provides a way for NMI reported errors on x86 to notify the EDAC subsystem pending ECC errors by writing to a software state variable. Here's the reworked patch. I added an EDAC stub to the kernel so we can have variables that are in the kernel even if EDAC is a module. I also implemented the idea of using the chip driver to select error detection mode via module parameter and eliminate the kernel compile option. Please review/test. Thx! Also, I only made changes to some of the chipset drivers since I am unfamiliar with the other ones. We can add similar changes as we go. Signed-off-by: NDave Jiang <djiang@mvista.com> Signed-off-by: NDouglas Thompson <dougthompson@xmission.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Rusty Russell 提交于
This is the structure offsets required by lg.ko's switcher.S. Unfortunately we don't have infrastructure for private asm-offsets creation. Signed-off-by: NRusty Russell <rusty@rustcorp.com.au> Cc: Andi Kleen <ak@suse.de> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Rusty Russell 提交于
This is the code for the "lg.ko" module, which allows lguest guests to be launched. [akpm@linux-foundation.org: update for futex-new-private-futexes] [akpm@linux-foundation.org: build fix] [jmorris@namei.org: lguest: use hrtimers] [akpm@linux-foundation.org: x86_64 build fix] Signed-off-by: NRusty Russell <rusty@rustcorp.com.au> Cc: Andi Kleen <ak@suse.de> Cc: Eric Dumazet <dada1@cosmosbay.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Rusty Russell 提交于
lguest does some fairly lowlevel things to support a host, which normal modules don't need: math_state_restore: When the guest triggers a Device Not Available fault, we need to be able to restore the FPU __put_task_struct: We need to hold a reference to another task for inter-guest I/O, and put_task_struct() is an inline function which calls __put_task_struct. access_process_vm: We need to access another task for inter-guest I/O. map_vm_area & __get_vm_area: We need to map the switcher shim (ie. monitor) at 0xFFC01000. Signed-off-by: NRusty Russell <rusty@rustcorp.com.au> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Roland McGrath 提交于
This changes the i386 linker script and the asm-generic macro it uses so that ELF note sections with SHF_ALLOC set are linked into the kernel image along with other read-only data. The PT_NOTE also points to their location. This paves the way for putting useful build-time information into ELF notes that can be found easily later in a kernel memory dump. Signed-off-by: NRoland McGrath <roland@redhat.com> Cc: Andi Kleen <ak@suse.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Fenghua Yu 提交于
Currently most of the per cpu data, which is accessed by different cpus, has a ____cacheline_aligned_in_smp attribute. Move all this data to the new per cpu shared data section: .data.percpu.shared_aligned. This will seperate the percpu data which is referenced frequently by other cpus from the local only percpu data. Signed-off-by: NFenghua Yu <fenghua.yu@intel.com> Acked-by: NSuresh Siddha <suresh.b.siddha@intel.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Christoph Lameter <clameter@sgi.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Fenghua Yu 提交于
per cpu data section contains two types of data. One set which is exclusively accessed by the local cpu and the other set which is per cpu, but also shared by remote cpus. In the current kernel, these two sets are not clearely separated out. This can potentially cause the same data cacheline shared between the two sets of data, which will result in unnecessary bouncing of the cacheline between cpus. One way to fix the problem is to cacheline align the remotely accessed per cpu data, both at the beginning and at the end. Because of the padding at both ends, this will likely cause some memory wastage and also the interface to achieve this is not clean. This patch: Moves the remotely accessed per cpu data (which is currently marked as ____cacheline_aligned_in_smp) into a different section, where all the data elements are cacheline aligned. And as such, this differentiates the local only data and remotely accessed data cleanly. Signed-off-by: NFenghua Yu <fenghua.yu@intel.com> Acked-by: NSuresh Siddha <suresh.b.siddha@intel.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Christoph Lameter <clameter@sgi.com> Cc: <linux-arch@vger.kernel.org> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Pavel Machek 提交于
Move "debug during resume from s2ram" into the variable we already use for real-mode flags to simplify code. It also closes nasty trap for the user in acpi_sleep_setup; order of parameters actually mattered there, acpi_sleep=s3_bios,s3_mode doing something different from acpi_sleep=s3_mode,s3_bios. Signed-off-by: NPavel Machek <pavel@suse.cz> Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Nigel Cunningham 提交于
Add a feature allowing the user to make the system beep during a resume from suspend to RAM, on x86_64 and i386. This is useful for the users with broken resume from RAM, so that they can verify if the control reaches the kernel after a wake-up event. Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Nick Piggin 提交于
This patch completes Linus's wish that the fault return codes be made into bit flags, which I agree makes everything nicer. This requires requires all handle_mm_fault callers to be modified (possibly the modifications should go further and do things like fault accounting in handle_mm_fault -- however that would be for another patch). [akpm@linux-foundation.org: fix alpha build] [akpm@linux-foundation.org: fix s390 build] [akpm@linux-foundation.org: fix sparc build] [akpm@linux-foundation.org: fix sparc64 build] [akpm@linux-foundation.org: fix ia64 build] Signed-off-by: NNick Piggin <npiggin@suse.de> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ian Molton <spyro@f2s.com> Cc: Bryan Wu <bryan.wu@analog.com> Cc: Mikael Starvik <starvik@axis.com> Cc: David Howells <dhowells@redhat.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Greg Ungerer <gerg@uclinux.org> Cc: Matthew Wilcox <willy@debian.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp> Cc: Richard Curnow <rc@rc0.org.uk> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp> Cc: Chris Zankel <chris@zankel.net> Acked-by: NKyle McMartin <kyle@mcmartin.ca> Acked-by: NHaavard Skinnemoen <hskinnemoen@atmel.com> Acked-by: NRalf Baechle <ralf@linux-mips.org> Acked-by: NAndi Kleen <ak@muc.de> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> [ Still apparently needs some ARM and PPC loving - Linus ] Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 19 7月, 2007 7 次提交
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由 Peter Zijlstra 提交于
The TRACE_IRQS_ON function in iret_exc: calls a C function without ensuring that the segments are set properly. Move the trace function and the enabling of interrupt into the C stub. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Roland McGrath 提交于
The code for LDT segment selectors was not robust in the face of a bogus selector set in %cs via ptrace before the single-step was done. Signed-off-by: NRoland McGrath <roland@redhat.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Sam Ravnborg 提交于
Keep the arch/i386/boot directory from being rebuilt every time. Signed-off-by: NSam Ravnborg <sam@ravnborg.org> Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
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由 H. Peter Anvin 提交于
There exists at least one card, Trident TVGA8900CL (BIOS dated 1992/9/8) which clobbers DS when "scrolling in an SVGA text mode of more than 800x600 pixels." Although we are extremely unlikely to run into that situation, it is cheap insurance to save and restore DS, and it only adds a grand total of 50 bytes to the total output. Pointed out by Etienne Lorrain. Cc: Etienne Lorrain <etienne_lorrain@yahoo.fr> Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
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由 H. Peter Anvin 提交于
If the user has asked for the vertical height registers to be recomputed by setting bit 15 in the video mode number, we do so without clearing the Protect bit in the Vertical Retrace Register before setting the Overflow register. As a result, if the VGA BIOS had set the Protect bit, the write to the Overflow register will be dropped, and bits [9:8] of the vertical height will be left unchanged. This is a bug imported from the assembly version of this code. It was pointed out by Etienne Lorrain. Cc: Etienne Lorrain <etienne_lorrain@yahoo.fr> Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
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由 H. Peter Anvin 提交于
Fix incorrect assembly constraints. In particular, fix memory constraints used inside push..pop, which can cause invalid operation since gcc may generate %esp-relative references. Additionally: outl() should have "dN" not "dn". query_mca() shouldn't listen 16/32-bit registers in an 8-bit only context. has_eflag(): the "mask" is only used well after both the stack pointer and the output registers have been touched; this requires the output registers to be earlyclobbers (=&) and the input to exclude memory (so "ri", not "g"). Thanks to Etienne Lorrain and Chuck Ebbert for prompting this review. Cc: Etienne Lorrain <etienne_lorrain@yahoo.fr> Cc: Chuck Ebbert <cebbert@redhat.com> Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
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由 H. Peter Anvin 提交于
Correct a comment in arch/i386/boot/build/tools.c; we now build the kernel from only two components instead of three, since the boot sector has been integrated in the setup code. Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
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- 18 7月, 2007 23 次提交
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由 Jeremy Fitzhardinge 提交于
A domU Xen environment has no non-virtual drivers, so make sure they're all disabled at once. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Cc: Rusty Russell <rusty@rustcorp.com.au>
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由 Jeremy Fitzhardinge 提交于
Most of the time we can simply use the iret instruction to exit the kernel, rather than having to use the iret hypercall - the only exception is if we're returning into vm86 mode, or from delivering an NMI (which we don't support yet). When running native, iret has the behaviour of testing for a pending interrupt atomically with re-enabling interrupts. Unfortunately there's no way to do this with Xen, so there's a window in which we could get a recursive exception after enabling events but before actually returning to userspace. This causes a problem: if the nested interrupt causes one of the task's TIF_WORK_MASK flags to be set, they will not be checked again before returning to userspace. This means that pending work may be left pending indefinitely, until the process enters and leaves the kernel again. The net effect is that a pending signal or reschedule event could be delayed for an unbounded amount of time. To deal with this, the xen event upcall handler checks to see if the EIP is within the critical section of the iret code, after events are (potentially) enabled up to the iret itself. If its within this range, it calls the iret critical section fixup, which adjusts the stack to deal with any unrestored registers, and then shifts the stack frame up to replace the previous invocation. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
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由 Jeremy Fitzhardinge 提交于
arch/i386/xen/xen-asm.S defines some small pieces of code which are used to implement a few paravirt_ops. They're designed so they can be used either in-place, or be inline patched into their callsites if there's enough space. Some of those operations need to make calls out (specifically, if you re-enable events [interrupts], and there's a pending event at that time). These calls need the call instruction to be relocated if the code is patched inline. In this case xen_foo_reloc is a section-relative symbol which points to xen_foo's required relocation. Other operations have no need of a relocation, and so their corresponding xen_bar_reloc is absolute 0. These are the cases which are triggering the warning. This patch adds those symbols to the list of safe abs symbols. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Cc: Adrian Bunk <bunk@stusta.de>
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由 Jeremy Fitzhardinge 提交于
This patchs adds the mechanism to allow us to patch inline versions of common operations. The implementations of the direct-access versions save_fl, restore_fl, irq_enable and irq_disable are now in assembler, and the same code is used for both out of line and inline uses. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Keir Fraser <keir@xensource.com>
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由 Jeremy Fitzhardinge 提交于
An experimental patch for Xen allows guests to place their vcpu_info structs anywhere. We try to use this to place the vcpu_info into the PDA, which allows direct access. If this works, then switch to using direct access operations for irq_enable, disable, save_fl and restore_fl. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Keir Fraser <keir@xensource.com>
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由 Jeremy Fitzhardinge 提交于
The guest domain can be asked to shutdown or reboot itself, or have a sysrq key injected, via xenbus. This patch adds a watcher for those events, and does the appropriate action. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Cc: Chris Wright <chrisw@sous-sol.org>
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由 Jeremy Fitzhardinge 提交于
Make the appropriate hypercalls to halt and reboot the virtual machine. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Acked-by: NChris Wright <chrisw@sous-sol.org>
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由 Jeremy Fitzhardinge 提交于
Implement a Xen back-end for hvc console. * * * Add early printk support via hvc console, enable using "earlyprintk=xen" on the kernel command line. From: Gerd Hoffmann <kraxel@suse.de> Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: NChris Wright <chrisw@sous-sol.org> Acked-by: NIngo Molnar <mingo@elte.hu> Acked-by: NOlof Johansson <olof@lixom.net>
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由 Jeremy Fitzhardinge 提交于
The hypervisor saves and restores the segment registers as part of the state is saves while context switching. If, during a context switch, the next process doesn't use the TLS segments, it invalidates the GDT entry, causing the segment register reload to fault. This fault effectively doubles the cost of a context switch. This patch is a band-aid workaround which clears the usermode %gs after it has been saved for the previous process, but before it gets reloaded for the next, and it avoids having the hypervisor attempt to erroneously reload it. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: NChris Wright <chrisw@sous-sol.org>
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由 Jeremy Fitzhardinge 提交于
This patch uses the lazy-mmu hooks to batch mmu operations where possible. This is primarily useful for batching operations applied to active pagetables, which happens during mprotect, munmap, mremap and the like (mmap does not do bulk pagetable operations, so it isn't helped). Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Acked-by: NChris Wright <chrisw@sous-sol.org>
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由 Jeremy Fitzhardinge 提交于
Add Xen support for preemption. This is mostly a cleanup of existing preempt_enable/disable calls, or just comments to explain the current usage. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: NChris Wright <chrisw@sous-sol.org>
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由 Jeremy Fitzhardinge 提交于
This is a fairly straightforward Xen implementation of smp_ops. Xen has its own IPI mechanisms, and has no dependency on any APIC-based IPI. The smp_ops hooks and the flush_tlb_others pv_op allow a Xen guest to avoid all APIC code in arch/i386 (the only apic operation is a single apic_read for the apic version number). One subtle point which needs to be addressed is unpinning pagetables when another cpu may have a lazy tlb reference to the pagetable. Xen will not allow an in-use pagetable to be unpinned, so we must find any other cpus with a reference to the pagetable and get them to shoot down their references. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: NChris Wright <chrisw@sous-sol.org> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Andi Kleen <ak@suse.de>
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由 Jeremy Fitzhardinge 提交于
Implement xen_sched_clock, which returns the number of ns the current vcpu has been actually in an unstolen state (ie, running or blocked, vs runnable-but-not-running, or offline) since boot. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Acked-by: NChris Wright <chrisw@sous-sol.org> Cc: john stultz <johnstul@us.ibm.com>
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由 Jeremy Fitzhardinge 提交于
This patch accounts for the time stolen from our VCPUs. Stolen time is time where a vcpu is runnable and could be running, but all available physical CPUs are being used for something else. This accounting gets run on each timer interrupt, just as a way to get it run relatively often, and when interesting things are going on. Stolen time is not really used by much in the kernel; it is reported in /proc/stats, and that's about it. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Acked-by: NChris Wright <chrisw@sous-sol.org> Cc: john stultz <johnstul@us.ibm.com> Cc: Rik van Riel <riel@redhat.com>
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由 Jeremy Fitzhardinge 提交于
When setting up the initial pagetable, which includes mappings of all low physical memory, ignore a mapping which tries to set the RW bit on an RO pte. An RO pte indicates a page which is part of the current pagetable, and so it cannot be allowed to become RW. Once xen_pagetable_setup_done is called, set_pte reverts to its normal behaviour. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Acked-by: NChris Wright <chrisw@sous-sol.org> Cc: ebiederm@xmission.com (Eric W. Biederman)
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由 Jeremy Fitzhardinge 提交于
Xen requires all active pagetables to be marked read-only. When the base of the pagetable is loaded into %cr3, the hypervisor validates the entire pagetable and only allows the load to proceed if it all checks out. This is pretty slow, so to mitigate this cost Xen has a notion of pinned pagetables. Pinned pagetables are pagetables which are considered to be active even if no processor's cr3 is pointing to is. This means that it must remain read-only and all updates are validated by the hypervisor. This makes context switches much cheaper, because the hypervisor doesn't need to revalidate the pagetable each time. This also adds a new paravirt hook which is called during setup once the zones and memory allocator have been initialized. When the init_mm pagetable is first built, the struct page array does not yet exist, and so there's nowhere to put he init_mm pagetable's PG_pinned flags. Once the zones are initialized and the struct page array exists, we can set the PG_pinned flags for those pages. This patch also adds the Xen support for pte pages allocated out of highmem (highpte) by implementing xen_kmap_atomic_pte. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: NChris Wright <chrisw@sous-sol.org> Cc: Zach Amsden <zach@vmware.com>
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由 Jeremy Fitzhardinge 提交于
Put config options for Xen after the core pieces are in place. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: NChris Wright <chrisw@sous-sol.org>
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由 Jeremy Fitzhardinge 提交于
Xen maintains a base clock which measures nanoseconds since system boot. This is provided to guests via a shared page which contains a base time in ns, a tsc timestamp at that point and tsc frequency parameters. Guests can compute the current time by reading the tsc and using it to extrapolate the current time from the basetime. The hypervisor makes sure that the frequency parameters are updated regularly, paricularly if the tsc changes rate or stops. This is implemented as a clocksource, so the interface to the rest of the kernel is a simple clocksource which simply returns the current time directly in nanoseconds. Xen also provides a simple timer mechanism, which allows a timeout to be set in the future. When that time arrives, a timer event is sent to the guest. There are two timer interfaces: - An old one which also delivers a stream of (unused) ticks at 100Hz, and on the same event, the actual timer events. The 100Hz ticks cause a lot of spurious wakeups, but are basically harmless. - The new timer interface doesn't have the 100Hz ticks, and can also fail if the specified time is in the past. This code presents the Xen timer as a clockevent driver, and uses the new interface by preference. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: NChris Wright <chrisw@sous-sol.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de>
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由 Jeremy Fitzhardinge 提交于
Xen implements interrupts in terms of event channels. Each guest domain gets 1024 event channels which can be used for a variety of purposes, such as Xen timer events, inter-domain events, inter-processor events (IPI) or for real hardware IRQs. Within the kernel, we map the event channels to IRQs, and implement the whole interrupt handling using a Xen irq_chip. Rather than setting NR_IRQ to 1024 under PARAVIRT in order to accomodate Xen, we create a dynamic mapping between event channels and IRQs. Ideally, Linux will eventually move towards dynamically allocating per-irq structures, and we can use a 1:1 mapping between event channels and irqs. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: NChris Wright <chrisw@sous-sol.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Eric W. Biederman <ebiederm@xmission.com>
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由 Jeremy Fitzhardinge 提交于
Xen pagetable handling, including the machinery to implement direct pagetables. Xen presents the real CPU's pagetables directly to guests, with no added shadowing or other layer of abstraction. Naturally this means the hypervisor must maintain close control over what the guest can put into the pagetable. When the guest modifies the pte/pmd/pgd, it must convert its domain-specific notion of a "physical" pfn into a global machine frame number (mfn) before inserting the entry into the pagetable. Xen will check to make sure the domain is allowed to create a mapping of the given mfn. Xen also requires that all mappings the guest has of its own active pagetable are read-only. This is relatively easy to implement in Linux because all pagetables share the same pte pages for kernel mappings, so updating the pte in one pagetable will implicitly update the mapping in all pagetables. Normally a pagetable becomes active when you point to it with cr3 (or the Xen equivalent), but when you do so, Xen must check the whole pagetable for correctness, which is clearly a performance problem. Xen solves this with pinning which keeps a pagetable effectively active even if its currently unused, which means that all the normal update rules are enforced. This means that it need not revalidate the pagetable when loading cr3. This patch has a first-cut implementation of pinning, but it is more fully implemented in a later patch. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: NChris Wright <chrisw@sous-sol.org>
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由 Jeremy Fitzhardinge 提交于
This patch is a rollup of all the core pieces of the Xen implementation, including: - booting and setup - pagetable setup - privileged instructions - segmentation - interrupt flags - upcalls - multicall batching BOOTING AND SETUP The vmlinux image is decorated with ELF notes which tell the Xen domain builder what the kernel's requirements are; the domain builder then constructs the address space accordingly and starts the kernel. Xen has its own entrypoint for the kernel (contained in an ELF note). The ELF notes are set up by xen-head.S, which is included into head.S. In principle it could be linked separately, but it seems to provoke lots of binutils bugs. Because the domain builder starts the kernel in a fairly sane state (32-bit protected mode, paging enabled, flat segments set up), there's not a lot of setup needed before starting the kernel proper. The main steps are: 1. Install the Xen paravirt_ops, which is simply a matter of a structure assignment. 2. Set init_mm to use the Xen-supplied pagetables (analogous to the head.S generated pagetables in a native boot). 3. Reserve address space for Xen, since it takes a chunk at the top of the address space for its own use. 4. Call start_kernel() PAGETABLE SETUP Once we hit the main kernel boot sequence, it will end up calling back via paravirt_ops to set up various pieces of Xen specific state. One of the critical things which requires a bit of extra care is the construction of the initial init_mm pagetable. Because Xen places tight constraints on pagetables (an active pagetable must always be valid, and must always be mapped read-only to the guest domain), we need to be careful when constructing the new pagetable to keep these constraints in mind. It turns out that the easiest way to do this is use the initial Xen-provided pagetable as a template, and then just insert new mappings for memory where a mapping doesn't already exist. This means that during pagetable setup, it uses a special version of xen_set_pte which ignores any attempt to remap a read-only page as read-write (since Xen will map its own initial pagetable as RO), but lets other changes to the ptes happen, so that things like NX are set properly. PRIVILEGED INSTRUCTIONS AND SEGMENTATION When the kernel runs under Xen, it runs in ring 1 rather than ring 0. This means that it is more privileged than user-mode in ring 3, but it still can't run privileged instructions directly. Non-performance critical instructions are dealt with by taking a privilege exception and trapping into the hypervisor and emulating the instruction, but more performance-critical instructions have their own specific paravirt_ops. In many cases we can avoid having to do any hypercalls for these instructions, or the Xen implementation is quite different from the normal native version. The privileged instructions fall into the broad classes of: Segmentation: setting up the GDT and the GDT entries, LDT, TLS and so on. Xen doesn't allow the GDT to be directly modified; all GDT updates are done via hypercalls where the new entries can be validated. This is important because Xen uses segment limits to prevent the guest kernel from damaging the hypervisor itself. Traps and exceptions: Xen uses a special format for trap entrypoints, so when the kernel wants to set an IDT entry, it needs to be converted to the form Xen expects. Xen sets int 0x80 up specially so that the trap goes straight from userspace into the guest kernel without going via the hypervisor. sysenter isn't supported. Kernel stack: The esp0 entry is extracted from the tss and provided to Xen. TLB operations: the various TLB calls are mapped into corresponding Xen hypercalls. Control registers: all the control registers are privileged. The most important is cr3, which points to the base of the current pagetable, and we handle it specially. Another instruction we treat specially is CPUID, even though its not privileged. We want to control what CPU features are visible to the rest of the kernel, and so CPUID ends up going into a paravirt_op. Xen implements this mainly to disable the ACPI and APIC subsystems. INTERRUPT FLAGS Xen maintains its own separate flag for masking events, which is contained within the per-cpu vcpu_info structure. Because the guest kernel runs in ring 1 and not 0, the IF flag in EFLAGS is completely ignored (and must be, because even if a guest domain disables interrupts for itself, it can't disable them overall). (A note on terminology: "events" and interrupts are effectively synonymous. However, rather than using an "enable flag", Xen uses a "mask flag", which blocks event delivery when it is non-zero.) There are paravirt_ops for each of cli/sti/save_fl/restore_fl, which are implemented to manage the Xen event mask state. The only thing worth noting is that when events are unmasked, we need to explicitly see if there's a pending event and call into the hypervisor to make sure it gets delivered. UPCALLS Xen needs a couple of upcall (or callback) functions to be implemented by each guest. One is the event upcalls, which is how events (interrupts, effectively) are delivered to the guests. The other is the failsafe callback, which is used to report errors in either reloading a segment register, or caused by iret. These are implemented in i386/kernel/entry.S so they can jump into the normal iret_exc path when necessary. MULTICALL BATCHING Xen provides a multicall mechanism, which allows multiple hypercalls to be issued at once in order to mitigate the cost of trapping into the hypervisor. This is particularly useful for context switches, since the 4-5 hypercalls they would normally need (reload cr3, update TLS, maybe update LDT) can be reduced to one. This patch implements a generic batching mechanism for hypercalls, which gets used in many places in the Xen code. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: NChris Wright <chrisw@sous-sol.org> Cc: Ian Pratt <ian.pratt@xensource.com> Cc: Christian Limpach <Christian.Limpach@cl.cam.ac.uk> Cc: Adrian Bunk <bunk@stusta.de>
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由 Jeremy Fitzhardinge 提交于
Add the "nosegneg" fake capabilty to the vsyscall page notes. This is used by the runtime linker to select a glibc version which then disables negative-offset accesses to the thread-local segment via %gs. These accesses require emulation in Xen (because segments are truncated to protect the hypervisor address space) and avoiding them provides a measurable performance boost. Signed-off-by: NIan Pratt <ian.pratt@xensource.com> Signed-off-by: NChristian Limpach <Christian.Limpach@cl.cam.ac.uk> Signed-off-by: NChris Wright <chrisw@sous-sol.org> Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Acked-by: NZachary Amsden <zach@vmware.com> Cc: Roland McGrath <roland@redhat.com> Cc: Ulrich Drepper <drepper@redhat.com>
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由 Jeremy Fitzhardinge 提交于
The tsc-based get_scheduled_cycles interface is not a good match for Xen's runstate accounting, which reports everything in nanoseconds. This patch replaces this interface with a sched_clock interface, which matches both Xen and VMI's requirements. In order to do this, we: 1. replace get_scheduled_cycles with sched_clock 2. hoist cycles_2_ns into a common header 3. update vmi accordingly One thing to note: because sched_clock is implemented as a weak function in kernel/sched.c, we must define a real function in order to override this weak binding. This means the usual paravirt_ops technique of using an inline function won't work in this case. Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com> Cc: Zachary Amsden <zach@vmware.com> Cc: Dan Hecht <dhecht@vmware.com> Cc: john stultz <johnstul@us.ibm.com>
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