- 27 4月, 2017 5 次提交
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由 Paolo Bonzini 提交于
kvm_make_all_requests() provides a synchronization that waits until all kicked VCPUs have acknowledged the kick. This is important for KVM_REQ_MMU_RELOAD as it prevents freeing while lockless paging is underway. This patch adds the synchronization property into all requests that are currently being used with kvm_make_all_requests() in order to preserve the current behavior and only introduce a new framework. Removing it from requests where it is not necessary is left for future patches. Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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由 Radim Krčmář 提交于
No need to kick a VCPU that we have just woken up. Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com> Reviewed-by: NAndrew Jones <drjones@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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由 Andrew Jones 提交于
kvm_vcpu_kick() must issue a general memory barrier prior to reading vcpu->mode in order to ensure correctness of the mutual-exclusion memory barrier pattern used with vcpu->requests. While the cmpxchg called from kvm_vcpu_kick(): kvm_vcpu_kick kvm_arch_vcpu_should_kick kvm_vcpu_exiting_guest_mode cmpxchg implies general memory barriers before and after the operation, that implication is only valid when cmpxchg succeeds. We need an explicit barrier for when it fails, otherwise a VCPU thread on its entry path that reads zero for vcpu->requests does not exclude the possibility the requesting thread sees !IN_GUEST_MODE when it reads vcpu->mode. kvm_make_all_cpus_request already had a barrier, so we remove it, as now it would be redundant. Signed-off-by: NAndrew Jones <drjones@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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由 Radim Krčmář 提交于
Some operations must ensure that the guest is not running with stale data, but if the guest is halted, then the update can wait until another event happens. kvm_make_all_requests() currently doesn't wake up, so we can mark all requests used with it. First 8 bits were arbitrarily reserved for request numbers. Most uses of requests have the request type as a constant, so a compiler will optimize the '&'. An alternative would be to have an inline function that would return whether the request needs a wake-up or not, but I like this one better even though it might produce worse assembly. Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com> Reviewed-by: NAndrew Jones <drjones@redhat.com> Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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由 Radim Krčmář 提交于
Users were expected to use kvm_check_request() for testing and clearing, but request have expanded their use since then and some users want to only test or do a faster clear. Make sure that requests are not directly accessed with bit operations. Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com> Reviewed-by: NAndrew Jones <drjones@redhat.com> Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 13 4月, 2017 1 次提交
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由 David Hildenbrand 提交于
Let's rename it into a proper arch specific callback. Signed-off-by: NDavid Hildenbrand <david@redhat.com> Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
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- 07 4月, 2017 2 次提交
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由 Paolo Bonzini 提交于
Its value has never changed; we might as well make it part of the ABI instead of using the return value of KVM_CHECK_EXTENSION(KVM_CAP_COALESCED_MMIO). Because PPC does not always make MMIO available, the code has to be made dependent on CONFIG_KVM_MMIO rather than KVM_COALESCED_MMIO_PAGE_OFFSET. Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com> Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
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由 Paolo Bonzini 提交于
Legacy device assignment has been deprecated since 4.2 (released 1.5 years ago). VFIO is better and everyone should have switched to it. If they haven't, this should convince them. :) Reviewed-by: NAlex Williamson <alex.williamson@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 24 3月, 2017 1 次提交
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由 David Hildenbrand 提交于
No caller currently checks the return value of kvm_io_bus_unregister_dev(). This is evil, as all callers silently go on freeing their device. A stale reference will remain in the io_bus, getting at least used again, when the iobus gets teared down on kvm_destroy_vm() - leading to use after free errors. There is nothing the callers could do, except retrying over and over again. So let's simply remove the bus altogether, print an error and make sure no one can access this broken bus again (returning -ENOMEM on any attempt to access it). Fixes: e93f8a0f ("KVM: convert io_bus to SRCU") Cc: stable@vger.kernel.org # 3.4+ Reported-by: NDmitry Vyukov <dvyukov@google.com> Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: NDavid Hildenbrand <david@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 02 3月, 2017 1 次提交
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由 Elena Reshetova 提交于
refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Signed-off-by: NElena Reshetova <elena.reshetova@intel.com> Signed-off-by: NHans Liljestrand <ishkamiel@gmail.com> Signed-off-by: NKees Cook <keescook@chromium.org> Signed-off-by: NDavid Windsor <dwindsor@gmail.com> Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
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- 17 2月, 2017 2 次提交
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由 Paolo Bonzini 提交于
The FPU is always active now when running KVM. Reviewed-by: NDavid Matlack <dmatlack@google.com> Reviewed-by: NBandan Das <bsd@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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由 Cao, Lei 提交于
Provide versions of struct gfn_to_hva_cache functions that take vcpu as a parameter instead of struct kvm. The existing functions are not needed anymore, so delete them. This allows dirty pages to be logged in the vcpu dirty ring, instead of the global dirty ring, for ring-based dirty memory tracking. Signed-off-by: NLei Cao <lei.cao@stratus.com> Message-Id: <CY1PR08MB19929BD2AC47A291FD680E83F04F0@CY1PR08MB1992.namprd08.prod.outlook.com> Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 30 1月, 2017 1 次提交
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由 Marc Zyngier 提交于
KVM_MEMSLOT_INCOHERENT is not used anymore, as we've killed its only use in the arm/arm64 MMU code. Let's remove the last artifacts. Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org> Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
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- 28 11月, 2016 1 次提交
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由 Suraj Jitindar Singh 提交于
The kvm module has the parameters halt_poll_ns, halt_poll_ns_grow, and halt_poll_ns_shrink. Halt polling was recently added to the powerpc kvm-hv module and these parameters were essentially duplicated for that. There is no benefit to this duplication and it can lead to confusion when trying to tune halt polling. Thus move the definition of these variables to kvm_host.h and export them. This will allow the kvm-hv module to use the same module parameters by accessing these variables, which will be implemented in the next patch, meaning that they will no longer be duplicated. Signed-off-by: NSuraj Jitindar Singh <sjitindarsingh@gmail.com> Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
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- 23 11月, 2016 1 次提交
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由 Bandan Das 提交于
Change unimplemented msrs messages to use pr_debug. If CONFIG_DYNAMIC_DEBUG is set, then these messages can be enabled at run time or else -DDEBUG can be used at compile time to enable them. These messages will still be printed if ignore_msrs=1. Signed-off-by: NBandan Das <bsd@redhat.com> Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com> Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
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- 22 11月, 2016 1 次提交
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由 Pan Xinhui 提交于
It allows us to update some status or field of a structure partially. We can also save a kvm_read_guest_cached() call if we just update one fild of the struct regardless of its current value. Signed-off-by: NPan Xinhui <xinhui.pan@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Acked-by: NPaolo Bonzini <pbonzini@redhat.com> Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: benh@kernel.crashing.org Cc: boqun.feng@gmail.com Cc: borntraeger@de.ibm.com Cc: bsingharora@gmail.com Cc: dave@stgolabs.net Cc: jgross@suse.com Cc: kernellwp@gmail.com Cc: konrad.wilk@oracle.com Cc: linuxppc-dev@lists.ozlabs.org Cc: mpe@ellerman.id.au Cc: paulmck@linux.vnet.ibm.com Cc: paulus@samba.org Cc: rkrcmar@redhat.com Cc: virtualization@lists.linux-foundation.org Cc: will.deacon@arm.com Cc: xen-devel-request@lists.xenproject.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1478077718-37424-8-git-send-email-xinhui.pan@linux.vnet.ibm.com [ Typo fixes. ] Signed-off-by: NIngo Molnar <mingo@kernel.org>
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- 07 10月, 2016 1 次提交
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由 Rik van Riel 提交于
With the removal of the lazy FPU code, this field is no longer used. Get rid of it. Signed-off-by: NRik van Riel <riel@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: pbonzini@redhat.com Link: http://lkml.kernel.org/r/1475627678-20788-7-git-send-email-riel@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 16 9月, 2016 2 次提交
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由 Luiz Capitulino 提交于
This commit adds the ability for archs to export per-vcpu information via a new per-vcpu dir in the VM's debugfs directory. If kvm_arch_has_vcpu_debugfs() returns true, then KVM will create a vcpu dir for each vCPU in the VM's debugfs directory. Then kvm_arch_create_vcpu_debugfs() is responsible for populating each vcpu directory with arch specific entries. The per-vcpu path in debugfs will look like: /sys/kernel/debug/kvm/29162-10/vcpu0 /sys/kernel/debug/kvm/29162-10/vcpu1 This is all arch specific for now because the only user of this interface (x86) wants to export x86-specific per-vcpu information to user-space. Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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由 Luiz Capitulino 提交于
Two stubs are added: o kvm_arch_has_vcpu_debugfs(): must return true if the arch supports creating debugfs entries in the vcpu debugfs dir (which will be implemented by the next commit) o kvm_arch_create_vcpu_debugfs(): code that creates debugfs entries in the vcpu debugfs dir For x86, this commit introduces a new file to avoid growing arch/x86/kvm/x86.c even more. Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 12 8月, 2016 2 次提交
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由 Christoffer Dall 提交于
KVM devices were manipulating list data structures without any form of synchronization, and some implementations of the create operations also suffered from a lack of synchronization. Now when we've split the xics create operation into create and init, we can hold the kvm->lock mutex while calling the create operation and when manipulating the devices list. The error path in the generic code gets slightly ugly because we have to take the mutex again and delete the device from the list, but holding the mutex during anon_inode_getfd or releasing/locking the mutex in the common non-error path seemed wrong. Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org> Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com> Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
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由 Christoffer Dall 提交于
As we are about to hold the kvm->lock during the create operation on KVM devices, we should move the call to xics_debugfs_init into its own function, since holding a mutex over extended amounts of time might not be a good idea. Introduce an init operation on the kvm_device_ops struct which cannot fail and call this, if configured, after the device has been created. Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org> Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com> Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
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- 23 7月, 2016 3 次提交
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由 Eric Auger 提交于
Up to now, only irqchip routing entries could be set. This patch adds the capability to insert MSI routing entries. For ARM64, let's also increase KVM_MAX_IRQ_ROUTES to 4096: this include SPI irqchip routes plus MSI routes. In the future this might be extended. Signed-off-by: NEric Auger <eric.auger@redhat.com> Reviewed-by: NAndre Przywara <andre.przywara@arm.com> Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
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由 Eric Auger 提交于
kvm_setup_default_irq_routing and kvm_setup_empty_irq_routing are not used by generic code. So let's move the declarations in x86 irq.h header instead of kvm_host.h. Signed-off-by: NEric Auger <eric.auger@redhat.com> Suggested-by: NAndre Przywara <andre.przywara@arm.com> Acked-by: NRadim Krčmář <rkrcmar@redhat.com> Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
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由 Eric Auger 提交于
Enhance kvm_kernel_irq_routing_entry to transport the device id field, devid. A new flags field makes possible to indicate the devid is valid. Those additions are used for ARM GICv3 ITS MSI injection. The original struct msi_msg msi field is replaced by a new custom structure that embeds the new fields. Signed-off-by: NEric Auger <eric.auger@redhat.com> Suggested-by: NRadim Krčmář <rkrcmar@redhat.com> Acked-by: NRadim Krčmář <rkrcmar@redhat.com> Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
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- 19 7月, 2016 1 次提交
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由 Andre Przywara 提交于
The kvm_io_bus framework is a nice place of holding information about various MMIO regions for kernel emulated devices. Add a call to retrieve the kvm_io_device structure which is associated with a certain MMIO address. This avoids to duplicate kvm_io_bus' knowledge of MMIO regions without having to fake MMIO calls if a user needs the device a certain MMIO address belongs to. This will be used by the ITS emulation to get the associated ITS device when someone triggers an MSI via an ioctl from userspace. Signed-off-by: NAndre Przywara <andre.przywara@arm.com> Reviewed-by: NEric Auger <eric.auger@redhat.com> Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com> Acked-by: NChristoffer Dall <christoffer.dall@linaro.org> Acked-by: NPaolo Bonzini <pbonzini@redhat.com> Tested-by: NEric Auger <eric.auger@redhat.com> Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
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- 14 7月, 2016 1 次提交
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由 Radim Krčmář 提交于
Arch-specific code will use it. Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 01 7月, 2016 1 次提交
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由 Paolo Bonzini 提交于
Use the functions from context_tracking.h directly. Cc: Andy Lutomirski <luto@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: NRik van Riel <riel@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 28 6月, 2016 1 次提交
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由 Paolo Bonzini 提交于
Make kvm_guest_{enter,exit} and __kvm_guest_{enter,exit} trivial wrappers around the code in context_tracking.h. Name the context_tracking.h functions consistently with what those for kernel<->user switch. Cc: Andy Lutomirski <luto@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: NRik van Riel <riel@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 16 6月, 2016 2 次提交
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由 Paolo Bonzini 提交于
The new created_vcpus field makes it possible to avoid the race between irqchip and VCPU creation in a much nicer way; just check under kvm->lock whether a VCPU has already been created. We can then remove KVM_APIC_ARCHITECTURE too, because at this point the symbol is only governing the default definition of kvm_vcpu_compatible. Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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由 Paolo Bonzini 提交于
The race between creating the irqchip and the first VCPU is currently fixed by checking the presence of an irqchip before updating kvm->online_vcpus, and undoing the whole VCPU creation if someone created the irqchip in the meanwhile. Instead, introduce a new field in struct kvm that will count VCPUs under a mutex, without the atomic access and memory ordering that we need elsewhere to protect the vcpus array. This also plugs the race and is more easily applicable in all similar circumstances. Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 25 5月, 2016 1 次提交
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由 Janosch Frank 提交于
This patch adds a kvm debugfs subdirectory for each VM, which is named after its pid and file descriptor. The directories contain the same kind of files that are already in the kvm debugfs directory, but the data exported through them is now VM specific. This makes the debugfs kvm data a convenient alternative to the tracepoints which already have per VM data. The debugfs data is easy to read and low overhead. CC: Dan Carpenter <dan.carpenter@oracle.com> [includes fixes by Dan Carpenter] Signed-off-by: NJanosch Frank <frankja@linux.vnet.ibm.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 19 5月, 2016 1 次提交
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由 Radim Krčmář 提交于
AVIC has a use for kvm_vcpu_wake_up. Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com> Tested-by: NSuravee Suthikulpanit <suravee.suthikulpanit@amd.com> Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 13 5月, 2016 1 次提交
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由 Christian Borntraeger 提交于
Some wakeups should not be considered a sucessful poll. For example on s390 I/O interrupts are usually floating, which means that _ALL_ CPUs would be considered runnable - letting all vCPUs poll all the time for transactional like workload, even if one vCPU would be enough. This can result in huge CPU usage for large guests. This patch lets architectures provide a way to qualify wakeups if they should be considered a good/bad wakeups in regard to polls. For s390 the implementation will fence of halt polling for anything but known good, single vCPU events. The s390 implementation for floating interrupts does a wakeup for one vCPU, but the interrupt will be delivered by whatever CPU checks first for a pending interrupt. We prefer the woken up CPU by marking the poll of this CPU as "good" poll. This code will also mark several other wakeup reasons like IPI or expired timers as "good". This will of course also mark some events as not sucessful. As KVM on z runs always as a 2nd level hypervisor, we prefer to not poll, unless we are really sure, though. This patch successfully limits the CPU usage for cases like uperf 1byte transactional ping pong workload or wakeup heavy workload like OLTP while still providing a proper speedup. This also introduced a new vcpu stat "halt_poll_no_tuning" that marks wakeups that are considered not good for polling. Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com> Acked-by: Radim Krčmář <rkrcmar@redhat.com> (for an earlier version) Cc: David Matlack <dmatlack@google.com> Cc: Wanpeng Li <kernellwp@gmail.com> [Rename config symbol. - Paolo] Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 12 5月, 2016 3 次提交
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由 Alex Williamson 提交于
If we don't support a mechanism for bypassing IRQs, don't register as a consumer. This eliminates meaningless dev_info()s when the connect fails between producer and consumer, such as on AMD systems where kvm_x86_ops->update_pi_irte is not implemented Signed-off-by: NAlex Williamson <alex.williamson@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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由 Greg Kurz 提交于
The KVM_MAX_VCPUS define provides the maximum number of vCPUs per guest, and also the upper limit for vCPU ids. This is okay for all archs except PowerPC which can have higher ids, depending on the cpu/core/thread topology. In the worst case (single threaded guest, host with 8 threads per core), it limits the maximum number of vCPUS to KVM_MAX_VCPUS / 8. This patch separates the vCPU numbering from the total number of vCPUs, with the introduction of KVM_MAX_VCPU_ID, as the maximal valid value for vCPU ids plus one. The corresponding KVM_CAP_MAX_VCPU_ID allows userspace to validate vCPU ids before passing them to KVM_CREATE_VCPU. This patch only implements KVM_MAX_VCPU_ID with a specific value for PowerPC. Other archs continue to return KVM_MAX_VCPUS instead. Suggested-by: NRadim Krcmar <rkrcmar@redhat.com> Signed-off-by: NGreg Kurz <gkurz@linux.vnet.ibm.com> Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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由 Greg Kurz 提交于
Commit c896939f ("KVM: use heuristic for fast VCPU lookup by id") added a return path that prevents vcpu ids to exceed KVM_MAX_VCPUS. This is a problem for powerpc where vcpu ids can grow up to 8*KVM_MAX_VCPUS. This patch simply reverses the logic so that we only try fast path if the vcpu id can be tried as an index in kvm->vcpus[]. The slow path is not affected by the change. Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com> Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: NGreg Kurz <gkurz@linux.vnet.ibm.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 20 4月, 2016 1 次提交
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由 Paolo Bonzini 提交于
kvm_make_request and kvm_check_request imply a producer-consumer relationship; add implicit memory barriers to them. There was indeed already a place that was adding an explicit smp_mb() to order between kvm_check_request and the processing of the request. That memory barrier can be removed (as an added benefit, kvm_check_request can use smp_mb__after_atomic which is free on x86). Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 25 2月, 2016 1 次提交
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由 Marcelo Tosatti 提交于
The problem: On -rt, an emulated LAPIC timer instances has the following path: 1) hard interrupt 2) ksoftirqd is scheduled 3) ksoftirqd wakes up vcpu thread 4) vcpu thread is scheduled This extra context switch introduces unnecessary latency in the LAPIC path for a KVM guest. The solution: Allow waking up vcpu thread from hardirq context, thus avoiding the need for ksoftirqd to be scheduled. Normal waitqueues make use of spinlocks, which on -RT are sleepable locks. Therefore, waking up a waitqueue waiter involves locking a sleeping lock, which is not allowed from hard interrupt context. cyclictest command line: This patch reduces the average latency in my tests from 14us to 11us. Daniel writes: Paolo asked for numbers from kvm-unit-tests/tscdeadline_latency benchmark on mainline. The test was run 1000 times on tip/sched/core 4.4.0-rc8-01134-g0905f04e: ./x86-run x86/tscdeadline_latency.flat -cpu host with idle=poll. The test seems not to deliver really stable numbers though most of them are smaller. Paolo write: "Anything above ~10000 cycles means that the host went to C1 or lower---the number means more or less nothing in that case. The mean shows an improvement indeed." Before: min max mean std count 1000.000000 1000.000000 1000.000000 1000.000000 mean 5162.596000 2019270.084000 5824.491541 20681.645558 std 75.431231 622607.723969 89.575700 6492.272062 min 4466.000000 23928.000000 5537.926500 585.864966 25% 5163.000000 16132529.750000 5790.132275 16683.745433 50% 5175.000000 2281919.000000 5834.654000 23151.990026 75% 5190.000000 2382865.750000 5861.412950 24148.206168 max 5228.000000 4175158.000000 6254.827300 46481.048691 After min max mean std count 1000.000000 1000.00000 1000.000000 1000.000000 mean 5143.511000 2076886.10300 5813.312474 21207.357565 std 77.668322 610413.09583 86.541500 6331.915127 min 4427.000000 25103.00000 5529.756600 559.187707 25% 5148.000000 1691272.75000 5784.889825 17473.518244 50% 5160.000000 2308328.50000 5832.025000 23464.837068 75% 5172.000000 2393037.75000 5853.177675 24223.969976 max 5222.000000 3922458.00000 6186.720500 42520.379830 [Patch was originaly based on the swait implementation found in the -rt tree. Daniel ported it to mainline's version and gathered the benchmark numbers for tscdeadline_latency test.] Signed-off-by: NDaniel Wagner <daniel.wagner@bmw-carit.de> Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: linux-rt-users@vger.kernel.org Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1455871601-27484-4-git-send-email-wagi@monom.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 16 1月, 2016 1 次提交
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由 Dan Williams 提交于
To date, we have implemented two I/O usage models for persistent memory, PMEM (a persistent "ram disk") and DAX (mmap persistent memory into userspace). This series adds a third, DAX-GUP, that allows DAX mappings to be the target of direct-i/o. It allows userspace to coordinate DMA/RDMA from/to persistent memory. The implementation leverages the ZONE_DEVICE mm-zone that went into 4.3-rc1 (also discussed at kernel summit) to flag pages that are owned and dynamically mapped by a device driver. The pmem driver, after mapping a persistent memory range into the system memmap via devm_memremap_pages(), arranges for DAX to distinguish pfn-only versus page-backed pmem-pfns via flags in the new pfn_t type. The DAX code, upon seeing a PFN_DEV+PFN_MAP flagged pfn, flags the resulting pte(s) inserted into the process page tables with a new _PAGE_DEVMAP flag. Later, when get_user_pages() is walking ptes it keys off _PAGE_DEVMAP to pin the device hosting the page range active. Finally, get_page() and put_page() are modified to take references against the device driver established page mapping. Finally, this need for "struct page" for persistent memory requires memory capacity to store the memmap array. Given the memmap array for a large pool of persistent may exhaust available DRAM introduce a mechanism to allocate the memmap from persistent memory. The new "struct vmem_altmap *" parameter to devm_memremap_pages() enables arch_add_memory() to use reserved pmem capacity rather than the page allocator. This patch (of 18): The core has developed a need for a "pfn_t" type [1]. Move the existing pfn_t in KVM to kvm_pfn_t [2]. [1]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002199.html [2]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002218.htmlSigned-off-by: NDan Williams <dan.j.williams@intel.com> Acked-by: NChristoffer Dall <christoffer.dall@linaro.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 09 1月, 2016 1 次提交
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由 Paolo Bonzini 提交于
Since the numbers now overlap, it makes sense to enumerate them in asm/kvm_host.h rather than linux/kvm_host.h. Functions that refer to architecture-specific requests are also moved to arch/. Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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