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* x86, trace: Add irq vector tracepointsSeiji Aguchi2013-06-201-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [Purpose of this patch] As Vaibhav explained in the thread below, tracepoints for irq vectors are useful. http://www.spinics.net/lists/mm-commits/msg85707.html <snip> The current interrupt traces from irq_handler_entry and irq_handler_exit provide when an interrupt is handled. They provide good data about when the system has switched to kernel space and how it affects the currently running processes. There are some IRQ vectors which trigger the system into kernel space, which are not handled in generic IRQ handlers. Tracing such events gives us the information about IRQ interaction with other system events. The trace also tells where the system is spending its time. We want to know which cores are handling interrupts and how they are affecting other processes in the system. Also, the trace provides information about when the cores are idle and which interrupts are changing that state. <snip> On the other hand, my usecase is tracing just local timer event and getting a value of instruction pointer. I suggested to add an argument local timer event to get instruction pointer before. But there is another way to get it with external module like systemtap. So, I don't need to add any argument to irq vector tracepoints now. [Patch Description] Vaibhav's patch shared a trace point ,irq_vector_entry/irq_vector_exit, in all events. But there is an above use case to trace specific irq_vector rather than tracing all events. In this case, we are concerned about overhead due to unwanted events. So, add following tracepoints instead of introducing irq_vector_entry/exit. so that we can enable them independently. - local_timer_vector - reschedule_vector - call_function_vector - call_function_single_vector - irq_work_entry_vector - error_apic_vector - thermal_apic_vector - threshold_apic_vector - spurious_apic_vector - x86_platform_ipi_vector Also, introduce a logic switching IDT at enabling/disabling time so that a time penalty makes a zero when tracepoints are disabled. Detailed explanations are as follows. - Create trace irq handlers with entering_irq()/exiting_irq(). - Create a new IDT, trace_idt_table, at boot time by adding a logic to _set_gate(). It is just a copy of original idt table. - Register the new handlers for tracpoints to the new IDT by introducing macros to alloc_intr_gate() called at registering time of irq_vector handlers. - Add checking, whether irq vector tracing is on/off, into load_current_idt(). This has to be done below debug checking for these reasons. - Switching to debug IDT may be kicked while tracing is enabled. - On the other hands, switching to trace IDT is kicked only when debugging is disabled. In addition, the new IDT is created only when CONFIG_TRACING is enabled to avoid being used for other purposes. Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com> Link: http://lkml.kernel.org/r/51C323ED.5050708@hds.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: Steven Rostedt <rostedt@goodmis.org>
* xen: drop tracking of IRQ vectorJan Beulich2013-04-161-2/+1
| | | | | | | | | | | For quite a few Xen versions, this wasn't the IRQ vector anymore anyway, and it is not being used by the kernel for anything. Hence drop the field from struct irq_info, and respective function parameters. Signed-off-by: Jan Beulich <jbeulich@suse.com> Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen/arm: receive Xen events on ARMStefano Stabellini2012-09-141-0/+2
| | | | | | | | | | Compile events.c on ARM. Parse, map and enable the IRQ to get event notifications from the device tree (node "/xen"). Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen: do not map the same GSI twice in PVHVM guests.Stefano Stabellini2012-05-211-0/+3
| | | | | | | | | | | | | | | | | | PV on HVM guests map GSIs into event channels. At restore time the event channels are resumed by restore_pirqs. Device drivers might try to register the same GSI again through ACPI at restore time, but the GSI has already been mapped and bound by restore_pirqs. This patch detects these situations and avoids mapping the same GSI multiple times. Without this patch we get: (XEN) irq.c:2235: dom4: pirq 23 or emuirq 28 already mapped and waste a pirq. CC: stable@kernel.org Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen/event: Add reference counting to event channelsDaniel De Graaf2011-11-211-0/+7
| | | | | | | | | | | | | | | Event channels exposed to userspace by the evtchn module may be used by other modules in an asynchronous manner, which requires that reference counting be used to prevent the event channel from being closed before the signals are delivered. The reference count on new event channels defaults to -1 which indicates the event channel is not referenced outside the kernel; evtchn_get fails if called on such an event channel. The event channels made visible to userspace by evtchn have a normal reference count. Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen/pci: Remove 'xen_allocate_pirq_gsi'.Konrad Rzeszutek Wilk2011-07-111-2/+0
| | | | | | | | | | | | In the past (2.6.38) the 'xen_allocate_pirq_gsi' would allocate an entry in a Linux IRQ -> {XEN_IRQ, type, event, ..} array. All of that has been removed in 2.6.39 and the Xen IRQ subsystem uses an linked list that is populated when the call to 'xen_allocate_irq_gsi' (universally done from any of the xen_bind_* calls) is done. The 'xen_allocate_pirq_gsi' is a NOP and there is no need for it anymore so lets remove it. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen/irq: Export 'xen_pirq_from_irq' function.Konrad Rzeszutek Wilk2011-04-141-0/+3
| | | | | | | | | | | | We need this to find the real Xen PIRQ value for a device that requests an MSI or MSI-X. In the past we used 'xen_gsi_from_irq' since that function would return an Xen PIRQ or GSI depending on the provided IRQ. Now that we have seperated that we need to use the correct function. [v2: Deal with rebase on stable/irq.cleanup] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen/irq: Add support to check if IRQ line is shared with other domains.Konrad Rzeszutek Wilk2011-04-141-0/+3
| | | | | | | | | | | We do this via the PHYSDEVOP_irq_status_query support hypervisor call. We will get a positive value if another domain has binded its PIRQ to the specified GSI (IRQ line). [v2: Deal with v2.6.37-rc1 rebase fallout] [v3: Deal with stable/irq.cleanup fallout] [v4: xen_ignore_irq->xen_test_irq_shared] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen/irq: Check if the PCI device is owned by a domain different than DOMID_SELF.Konrad Rzeszutek Wilk2011-04-141-1/+2
| | | | | | | | | | | | | We check if there is a domain owner for the PCI device. In case of failure (meaning no domain has registered for this device) we make DOMID_SELF the owner. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> [v2: deal with rebasing on v2.6.37-1] [v3: deal with rebasing on stable/irq.cleanup] [v4: deal with rebasing on stable/irq.ween_of_nr_irqs] [v5: deal with rebasing on v2.6.39-rc3] Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Xiantao Zhang <xiantao.zhang@intel.com>
*-. Merge branches 'stable/irq.fairness' and 'stable/irq.ween_of_nr_irqs' of ↵Linus Torvalds2011-03-171-14/+10
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen * 'stable/irq.fairness' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen: xen: events: Remove redundant clear of l2i at end of round-robin loop xen: events: Make round-robin scan fairer by snapshotting each l2 word once only xen: events: Clean up round-robin evtchn scan. xen: events: Make last processed event channel a per-cpu variable. xen: events: Process event channels notifications in round-robin order. * 'stable/irq.ween_of_nr_irqs' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen: xen: events: Fix compile error if CONFIG_SMP is not defined. xen: events: correct locking in xen_irq_from_pirq xen: events: propagate irq allocation failure instead of panicking xen: events: do not workaround too-small nr_irqs xen: events: remove use of nr_irqs as upper bound on number of pirqs xen: events: dynamically allocate irq info structures xen: events: maintain a list of Xen interrupts xen: events: push setup of irq<->{evtchn,ipi,virq,pirq} maps into irq_info init functions xen: events: turn irq_info constructors into initialiser functions xen: events: use per-cpu variable for cpu_evtchn_mask xen: events: refactor GSI pirq bindings functions xen: events: rename restore_cpu_pirqs -> restore_pirqs xen: events: remove unused public functions xen: events: fix xen_map_pirq_gsi error return xen: events: simplify comment xen: events: separate two unrelated halves of if condition Fix up trivial conflicts in drivers/xen/events.c
| | * xen: events: refactor GSI pirq bindings functionsIan Campbell2011-03-101-3/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Following the example set by xen_allocate_pirq_msi and xen_bind_pirq_msi_to_irq: xen_allocate_pirq becomes xen_allocate_pirq_gsi and now only allocates a pirq number and does not bind it. xen_map_pirq_gsi becomes xen_bind_pirq_gsi_to_irq and binds an existing pirq. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
| | * xen: events: remove unused public functionsIan Campbell2011-03-101-9/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I was unable to find any user of these functions in either the functionality pending for 2.6.39 or the xen/next-2.6.32 branch of xen.git An exception to this was xen_gsi_from_irq which did appear to be used in xen/next-2.6.32's pciback. However in the 2.6.39 version of pciback xen_pirq_from_irq is, correctly AFAICT, used instead. Only a minority of functions in events.h use "extern" so drop it from those places for consistency. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
| | * xen: events: simplify commentIan Campbell2011-03-101-3/+1
| |/ | | | | | | | | | | | | | | | | It is never valid assume any particular relationship between a Xen PIRQ number and and Linux IRQ number so there is no need to hedge when saying so. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* | Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6Linus Torvalds2011-03-161-0/+6
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6: (1480 commits) bonding: enable netpoll without checking link status xfrm: Refcount destination entry on xfrm_lookup net: introduce rx_handler results and logic around that bonding: get rid of IFF_SLAVE_INACTIVE netdev->priv_flag bonding: wrap slave state work net: get rid of multiple bond-related netdevice->priv_flags bonding: register slave pointer for rx_handler be2net: Bump up the version number be2net: Copyright notice change. Update to Emulex instead of ServerEngines e1000e: fix kconfig for crc32 dependency netfilter ebtables: fix xt_AUDIT to work with ebtables xen network backend driver bonding: Improve syslog message at device creation time bonding: Call netif_carrier_off after register_netdevice bonding: Incorrect TX queue offset net_sched: fix ip_tos2prio xfrm: fix __xfrm_route_forward() be2net: Fix UDP packet detected status in RX compl Phonet: fix aligned-mode pipe socket buffer header reserve netxen: support for GbE port settings ... Fix up conflicts in drivers/staging/brcm80211/brcmsmac/wl_mac80211.c with the staging updates.
| * xen/irq: implement bind_interdomain_evtchn_to_irqhandler for backend driversIan Campbell2011-02-281-0/+6
| | | | | | | | | | | | | | | | Impact: new Xen-internal API Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* | xen: events: remove dom0 specific xen_create_msi_irqIan Campbell2011-03-101-1/+0
| | | | | | | | | | | | | | | | | | | | | | The function name does not distinguish it from xen_allocate_pirq_msi (which operates on domU and pvhvm domains rather than dom0). Hoist domain 0 specific functionality up into the only caller leaving functionality common to all guest types in xen_bind_pirq_msi_to_irq. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* | xen: events: use xen_bind_pirq_msi_to_irq from xen_create_msi_irqIan Campbell2011-03-101-1/+1
| | | | | | | | | | Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* | xen: events: separate MSI PIRQ allocation from PIRQ binding to IRQIan Campbell2011-03-101-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Split the binding aspect of xen_allocate_pirq_msi out into a new xen_bind_pirq_to_irq function. In xen_hvm_setup_msi_irq when allocating a pirq write the MSI message to signal the PIRQ as soon as the pirq is obtained. There is no way to free the pirq back so if the subsequent binding to an IRQ fails we want to ensure that we will reuse the PIRQ next time rather than leak it. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* | xen: events: return irq from xen_allocate_pirq_msiIan Campbell2011-03-101-1/+1
| | | | | | | | | | | | | | consistent with other similar functions. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* | xen: events: drop XEN_ALLOC_IRQ flag to xen_allocate_pirq_msiIan Campbell2011-03-101-4/+1
|/ | | | | | | All callers pass this flag so it is pointless. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen: fix MSI setup and teardown for PV on HVM guestsStefano Stabellini2010-12-021-1/+6
| | | | | | | | | | | | | | | | | | | When remapping MSIs into pirqs for PV on HVM guests, qemu is responsible for doing the actual mapping and unmapping. We only give qemu the desired pirq number when we ask to do the mapping the first time, after that we should be reading back the pirq number from qemu every time we want to re-enable the MSI. This fixes a bug in xen_hvm_setup_msi_irqs that manifests itself when trying to enable the same MSI for the second time: the old MSI to pirq mapping is still valid at this point but xen_hvm_setup_msi_irqs would try to assign a new pirq anyway. A simple way to reproduce this bug is to assign an MSI capable network card to a PV on HVM guest, if the user brings down the corresponding ethernet interface and up again, Linux would fail to enable MSIs on the device. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
* xen: make hvc_xen console work for dom0.Jeremy Fitzhardinge2010-10-221-0/+1
| | | | | | | | | | Use the console hypercalls for dom0 console. [ Impact: Add Xen dom0 console ] Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen: remap MSIs into pirqs when running as initial domainQing He2010-10-221-0/+4
| | | | | | | | | | | | Implement xen_create_msi_irq to create an msi and remap it as pirq. Use xen_create_msi_irq to implement an initial domain specific version of setup_msi_irqs. Signed-off-by: Qing He <qing.he@intel.com> Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen: map MSIs into pirqsStefano Stabellini2010-10-221-0/+2
| | | | | | | | Map MSIs into pirqs, writing 0 in the MSI vector data field and the pirq number in the MSI destination id field. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen: support pirq != irqStefano Stabellini2010-10-221-0/+1
| | | | | | | | | PHYSDEVOP_map_pirq might return a pirq different from what we asked if we are running as an HVM guest, so we need to be able to support pirqs that are different from linux irqs. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen/x86/PCI: Add support for the Xen PCI subsystemAlex Nixon2010-10-181-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | The frontend stub lives in arch/x86/pci/xen.c, alongside other sub-arch PCI init code (e.g. olpc.c). It provides a mechanism for Xen PCI frontend to setup/destroy legacy interrupts, MSI/MSI-X, and PCI configuration operations. [ Impact: add core of Xen PCI support ] [ v2: Removed the IOMMU code and only focusing on PCI.] [ v3: removed usage of pci_scan_all_fns as that does not exist] [ v4: introduced pci_xen value to fix compile warnings] [ v5: squished fixes+features in one patch, changed Reviewed-by to Ccs] [ v7: added Acked-by] Signed-off-by: Alex Nixon <alex.nixon@citrix.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: Qing He <qing.he@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86@kernel.org
* xen: fix shared irq device passthroughKonrad Rzeszutek Wilk2010-10-181-1/+1
| | | | | | | | | | | | | | | | | | | | In driver/xen/events.c, whether bind_pirq is shareable or not is determined by desc->action is NULL or not. But in __setup_irq, startup(irq) is invoked before desc->action is assigned with new action. So desc->action in startup_irq is always NULL, and bind_pirq is always not shareable. This results in pt_irq_create_bind failure when passthrough a device which shares irq to other devices. This patch doesn't use probing_irq to determine if pirq is shareable or not, instead set shareable flag in irq_info according to trigger mode in xen_allocate_pirq. Set level triggered interrupts shareable. Thus use this flag to set bind_pirq flag accordingly. [v2: arch/x86/xen/pci.c no more, so file skipped] Signed-off-by: Weidong Han <weidong.han@intel.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen: Provide a variant of xen_poll_irq with timeout.Konrad Rzeszutek Wilk2010-10-181-0/+4
| | | | | | | | | The 'xen_poll_irq_timeout' provides a method to pass in the poll timeout for IRQs if requested. We also export those two poll functions as Xen PCI fronted uses them. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
* xen: set pirq name to something useful.Gerd Hoffmann2010-10-181-1/+1
| | | | | | | | | | | | Impact: cleanup Make pirq show useful information in /proc/interrupts [v2: Removed the parts for arch/x86/xen/pci.c ] Signed-off-by: Gerd Hoffmann <kraxel@xeni.home.kraxel.org> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* xen: implement pirq type event channelsJeremy Fitzhardinge2010-10-181-0/+11
| | | | | | | | | | | | | | | | | | | | A privileged PV Xen domain can get direct access to hardware. In order for this to be useful, it must be able to get hardware interrupts. Being a PV Xen domain, all interrupts are delivered as event channels. PIRQ event channels are bound to a pirq number and an interrupt vector. When a IO APIC raises a hardware interrupt on that vector, it is delivered as an event channel, which we can deliver to the appropriate device driver(s). This patch simply implements the infrastructure for dealing with pirq event channels. [ Impact: integrate hardware interrupts into Xen's event scheme ] Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* x86/xen: event channels delivery on HVM.Sheng Yang2010-07-221-0/+7
| | | | | | | | | | | | | | | | Set the callback to receive evtchns from Xen, using the callback vector delivery mechanism. The traditional way for receiving event channel notifications from Xen is via the interrupts from the platform PCI device. The callback vector is a newer alternative that allow us to receive notifications on any vcpu and doesn't need any PCI support: we allocate a vector exclusively to receive events, in the vector handler we don't need to interact with the vlapic, therefore we avoid a VMEXIT. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Signed-off-by: Sheng Yang <sheng@linux.intel.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
* xen: add irq_from_evtchnIan Campbell2009-03-301-0/+3
| | | | | | | Given an evtchn, return the corresponding irq. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
* xen: save previous spinlock when blockingJeremy Fitzhardinge2008-08-211-0/+2
| | | | | | | | | | | | | | | | | | A spinlock can be interrupted while spinning, so make sure we preserve the previous lock of interest if we're taking a lock from within an interrupt handler. We also need to deal with the case where the blocking path gets interrupted between testing to see if the lock is free and actually blocking. If we get interrupted there and end up in the state where the lock is free but the irq isn't pending, then we'll block indefinitely in the hypervisor. This fix is to make sure that any nested lock-takers will always leave the irq pending if there's any chance the outer lock became free. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* xen: implement Xen-specific spinlocksJeremy Fitzhardinge2008-07-161-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The standard ticket spinlocks are very expensive in a virtual environment, because their performance depends on Xen's scheduler giving vcpus time in the order that they're supposed to take the spinlock. This implements a Xen-specific spinlock, which should be much more efficient. The fast-path is essentially the old Linux-x86 locks, using a single lock byte. The locker decrements the byte; if the result is 0, then they have the lock. If the lock is negative, then locker must spin until the lock is positive again. When there's contention, the locker spin for 2^16[*] iterations waiting to get the lock. If it fails to get the lock in that time, it adds itself to the contention count in the lock and blocks on a per-cpu event channel. When unlocking the spinlock, the locker looks to see if there's anyone blocked waiting for the lock by checking for a non-zero waiter count. If there's a waiter, it traverses the per-cpu "lock_spinners" variable, which contains which lock each CPU is waiting on. It picks one CPU waiting on the lock and sends it an event to wake it up. This allows efficient fast-path spinlock operation, while allowing spinning vcpus to give up their processor time while waiting for a contended lock. [*] 2^16 iterations is threshold at which 98% locks have been taken according to Thomas Friebel's Xen Summit talk "Preventing Guests from Spinning Around". Therefore, we'd expect the lock and unlock slow paths will only be entered 2% of the time. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Christoph Lameter <clameter@linux-foundation.org> Cc: Petr Tesarik <ptesarik@suse.cz> Cc: Virtualization <virtualization@lists.linux-foundation.org> Cc: Xen devel <xen-devel@lists.xensource.com> Cc: Thomas Friebel <thomas.friebel@amd.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* xen: implement save/restoreJeremy Fitzhardinge2008-05-271-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch implements Xen save/restore and migration. Saving is triggered via xenbus, which is polled in drivers/xen/manage.c. When a suspend request comes in, the kernel prepares itself for saving by: 1 - Freeze all processes. This is primarily to prevent any partially-completed pagetable updates from confusing the suspend process. If CONFIG_PREEMPT isn't defined, then this isn't necessary. 2 - Suspend xenbus and other devices 3 - Stop_machine, to make sure all the other vcpus are quiescent. The Xen tools require the domain to run its save off vcpu0. 4 - Within the stop_machine state, it pins any unpinned pgds (under construction or destruction), performs canonicalizes various other pieces of state (mostly converting mfns to pfns), and finally 5 - Suspend the domain Restore reverses the steps used to save the domain, ending when all the frozen processes are thawed. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* xen: add rebind_evtchn_irqJeremy Fitzhardinge2008-05-271-0/+1
| | | | | | | | | | Add rebind_evtchn_irq(), which will rebind an device driver's existing irq to a new event channel on restore. Since the new event channel will be masked and bound to vcpu0, we update the state accordingly and unmask the irq once everything is set up. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* xen: add resend_irq_on_evtchn() definition into events.cIsaku Yamahata2008-04-241-0/+1
| | | | | | | | | | | Define resend_irq_on_evtchn() which ia64/xen uses. Although it isn't used by current x86/xen code, it's arch generic so that put it into common code. Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* Xen: make events.c portable for ia64/xen supportIsaku Yamahata2008-04-241-7/+1
| | | | | | | | | | | | | | Remove x86 dependency in drivers/xen/events.c for ia64/xen support introducing include/asm/xen/events.h. Introduce xen_irqs_disabled() to hide regs->flags Introduce xen_do_IRQ() to hide regs->orig_ax. make enum ipi_vector definition arch specific. ia64/xen needs four vectors. Add one rmb() because on ia64 xchg() isn't barrier. Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* xen: use the hvc console infrastructure for Xen consoleJeremy Fitzhardinge2007-07-181-0/+1
| | | | | | | | | | | | | | 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: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Olof Johansson <olof@lixom.net>
* xen: SMP guest supportJeremy Fitzhardinge2007-07-181-4/+23
| | | | | | | | | | | | | | | | | | | | | 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: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Andi Kleen <ak@suse.de>
* xen: event channelsJeremy Fitzhardinge2007-07-181-0/+28
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: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Eric W. Biederman <ebiederm@xmission.com>
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