linux/arch/powerpc/kvm
Davidlohr Bueso da4ad88cab kvm: Replace vcpu->swait with rcuwait
The use of any sort of waitqueue (simple or regular) for
wait/waking vcpus has always been an overkill and semantically
wrong. Because this is per-vcpu (which is blocked) there is
only ever a single waiting vcpu, thus no need for any sort of
queue.

As such, make use of the rcuwait primitive, with the following
considerations:

  - rcuwait already provides the proper barriers that serialize
  concurrent waiter and waker.

  - Task wakeup is done in rcu read critical region, with a
  stable task pointer.

  - Because there is no concurrency among waiters, we need
  not worry about rcuwait_wait_event() calls corrupting
  the wait->task. As a consequence, this saves the locking
  done in swait when modifying the queue. This also applies
  to per-vcore wait for powerpc kvm-hv.

The x86 tscdeadline_latency test mentioned in 8577370fb0
("KVM: Use simple waitqueue for vcpu->wq") shows that, on avg,
latency is reduced by around 15-20% with this change.

Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: kvmarm@lists.cs.columbia.edu
Cc: linux-mips@vger.kernel.org
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Message-Id: <20200424054837.5138-6-dave@stgolabs.net>
[Avoid extra logic changes. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-13 12:14:56 -04:00
..
Kconfig vhost: refine vhost and vringh kconfig 2020-04-01 12:06:26 -04:00
Makefile KVM: PPC: Book3S HV: Support for running secure guests 2019-11-28 16:30:02 +11:00
book3s.c kvm_host: unify VM_STAT and VCPU_STAT definitions in a single place 2020-04-21 09:13:01 -04:00
book3s.h KVM: PPC: Book3S PR: Move kvmppc_mmu_init() into PR KVM 2020-03-19 16:39:52 +11:00
book3s_32_mmu.c KVM: PPC: Use fallthrough; 2020-03-19 16:39:52 +11:00
book3s_32_mmu_host.c KVM: PPC: Book3S PR: Move kvmppc_mmu_init() into PR KVM 2020-03-19 16:39:52 +11:00
book3s_32_sr.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
book3s_64_mmu.c KVM: PPC: Use fallthrough; 2020-03-19 16:39:52 +11:00
book3s_64_mmu_host.c KVM: PPC: Book3S PR: Move kvmppc_mmu_init() into PR KVM 2020-03-19 16:39:52 +11:00
book3s_64_mmu_hv.c PPC KVM fix for 5.7 2020-04-21 09:39:55 -04:00
book3s_64_mmu_radix.c PPC KVM fix for 5.7 2020-04-21 09:39:55 -04:00
book3s_64_slb.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
book3s_64_vio.c KVM: Remove unnecessary asm/kvm_host.h includes 2020-03-16 17:57:34 +01:00
book3s_64_vio_hv.c KVM: Remove unnecessary asm/kvm_host.h includes 2020-03-16 17:57:34 +01:00
book3s_emulate.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
book3s_exports.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
book3s_hv.c kvm: Replace vcpu->swait with rcuwait 2020-05-13 12:14:56 -04:00
book3s_hv_builtin.c KVM: PPC: Book3S HV: Implement LPCR[AIL]=3 mode for injected interrupts 2019-10-22 16:29:02 +11:00
book3s_hv_hmi.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 114 2019-05-24 17:39:01 +02:00
book3s_hv_interrupts.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
book3s_hv_nested.c KVM: PPC: Book3S: Define and use SRR1_MSR_BITS 2019-10-22 16:29:02 +11:00
book3s_hv_ras.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
book3s_hv_rm_mmu.c powerpc/mm: Fixup tlbie vs mtpidr/mtlpidr ordering issue on POWER9 2019-09-24 20:58:55 +10:00
book3s_hv_rm_xics.c KVM: PPC: Book3S HV: use smp_mb() when setting/clearing host_ipi flag 2019-09-24 12:46:26 +10:00
book3s_hv_rm_xive.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
book3s_hv_rmhandlers.S powerpc/64s/exception: Move KVM test to common code 2020-04-01 13:42:11 +11:00
book3s_hv_tm.c KVM: PPC: Book3S HV: Treat TM-related invalid form instructions on P9 like the valid ones 2020-03-19 16:39:52 +11:00
book3s_hv_tm_builtin.c KVM: PPC: Book3S HV: Treat TM-related invalid form instructions on P9 like the valid ones 2020-03-19 16:39:52 +11:00
book3s_hv_uvmem.c ARM: 2020-04-02 15:13:15 -07:00
book3s_interrupts.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
book3s_mmu_hpte.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
book3s_paired_singles.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
book3s_pr.c KVM: PPC: Fix kernel crash with PR KVM 2020-03-20 13:39:10 +11:00
book3s_pr_papr.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
book3s_rmhandlers.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
book3s_rtas.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
book3s_segment.S powerpc/64s/exception: Move KVM test to common code 2020-04-01 13:42:11 +11:00
book3s_xics.c scripts/spelling.txt: drop "sepc" from the misspelling list 2019-07-12 11:05:41 -07:00
book3s_xics.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
book3s_xive.c KVM: PPC: Book3S HV: XIVE: Fix typo in comment 2020-01-23 21:31:23 +11:00
book3s_xive.h KVM: PPC: Book3S HV: XIVE: Make VP block size configurable 2019-10-22 16:29:02 +11:00
book3s_xive_native.c KVM: Use vcpu-specific gva->hva translation when querying host page size 2020-01-27 20:00:02 +01:00
book3s_xive_template.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
booke.c kvm_host: unify VM_STAT and VCPU_STAT definitions in a single place 2020-04-21 09:13:01 -04:00
booke.h KVM: PPC: Kill kvmppc_ops::mmu_destroy() and kvmppc_mmu_destroy() 2020-03-19 16:43:07 +11:00
booke_emulate.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
booke_interrupts.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
bookehv_interrupts.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266 2019-06-05 17:30:28 +02:00
e500.c KVM: PPC: Kill kvmppc_ops::mmu_destroy() and kvmppc_mmu_destroy() 2020-03-19 16:43:07 +11:00
e500.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
e500_emulate.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
e500_mmu.c KVM: PPC: Kill kvmppc_ops::mmu_destroy() and kvmppc_mmu_destroy() 2020-03-19 16:43:07 +11:00
e500_mmu_host.c mm/vma: replace all remaining open encodings with is_vm_hugetlb_page() 2020-04-07 10:43:37 -07:00
e500_mmu_host.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
e500mc.c KVM: PPC: Kill kvmppc_ops::mmu_destroy() and kvmppc_mmu_destroy() 2020-03-19 16:43:07 +11:00
emulate.c Merge remote-tracking branch 'remotes/powerpc/topic/ppc-kvm' into kvm-ppc-next 2019-08-23 14:08:04 +10:00
emulate_loadstore.c KVM: PPC: Remove set but not used variable 'ra', 'rs', 'rt' 2020-01-17 15:08:28 +11:00
fpu.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
irq.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mpic.c KVM: Remove unnecessary asm/kvm_host.h includes 2020-03-16 17:57:34 +01:00
powerpc.c kvm: Replace vcpu->swait with rcuwait 2020-05-13 12:14:56 -04:00
timing.c powerpc/kvm: no need to check return value of debugfs_create functions 2020-03-04 22:44:25 +11:00
timing.h KVM: Remove unnecessary asm/kvm_host.h includes 2020-03-16 17:57:34 +01:00
tm.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
trace.h KVM: PPC: Move and undef TRACE_INCLUDE_PATH/FILE 2018-11-07 23:04:38 +11:00
trace_book3s.h KVM: PPC: Book3S: Simplify external interrupt handling 2018-10-09 16:04:27 +11:00
trace_booke.h KVM: PPC: Move and undef TRACE_INCLUDE_PATH/FILE 2018-11-07 23:04:38 +11:00
trace_hv.h KVM: PPC: Move and undef TRACE_INCLUDE_PATH/FILE 2018-11-07 23:04:38 +11:00
trace_pr.h KVM: PPC: Move and undef TRACE_INCLUDE_PATH/FILE 2018-11-07 23:04:38 +11:00