From: Sean Christopherson <seanjc@google.com>
To: Marc Zyngier <maz@kernel.org>,
Huacai Chen <chenhuacai@kernel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
Paul Mackerras <paulus@ozlabs.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
David Hildenbrand <david@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org,
kvm@vger.kernel.org, kvm-ppc@vger.kernel.org,
linux-kernel@vger.kernel.org, David Matlack <dmatlack@google.com>,
Jing Zhang <jingzhangos@google.com>
Subject: [PATCH 10/14] KVM: Split out a kvm_vcpu_block() helper from kvm_vcpu_halt()
Date: Fri, 24 Sep 2021 17:55:24 -0700 [thread overview]
Message-ID: <20210925005528.1145584-11-seanjc@google.com> (raw)
In-Reply-To: <20210925005528.1145584-1-seanjc@google.com>
Factor out the "block" part of kvm_vcpu_halt() so that x86 can emulate
non-halt wait/sleep/block conditions that should not be subjected to
halt-polling.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
include/linux/kvm_host.h | 1 +
virt/kvm/kvm_main.c | 50 ++++++++++++++++++++++++++++------------
2 files changed, 36 insertions(+), 15 deletions(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d2a8be3fb9ba..655c2b24db2d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -966,6 +966,7 @@ void kvm_sigset_activate(struct kvm_vcpu *vcpu);
void kvm_sigset_deactivate(struct kvm_vcpu *vcpu);
void kvm_vcpu_halt(struct kvm_vcpu *vcpu);
+bool kvm_vcpu_block(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu);
bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 280cf1dca7db..fe34457530c2 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3199,6 +3199,34 @@ static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu)
return ret;
}
+/*
+ * Block the vCPU until the vCPU is runnable, an event arrives, or a signal is
+ * pending. This is mostly used when halting a vCPU, but may also be used
+ * directly for other vCPU non-runnable states, e.g. x86's Wait-For-SIPI.
+ */
+bool kvm_vcpu_block(struct kvm_vcpu *vcpu)
+{
+ bool waited = false;
+
+ kvm_arch_vcpu_blocking(vcpu);
+
+ prepare_to_rcuwait(&vcpu->wait);
+ for (;;) {
+ set_current_state(TASK_INTERRUPTIBLE);
+
+ if (kvm_vcpu_check_block(vcpu) < 0)
+ break;
+
+ waited = true;
+ schedule();
+ }
+ finish_rcuwait(&vcpu->wait);
+
+ kvm_arch_vcpu_unblocking(vcpu);
+
+ return waited;
+}
+
static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start,
ktime_t end, bool success)
{
@@ -3221,6 +3249,12 @@ static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start,
}
}
+/*
+ * Emulate a vCPU halt condition, e.g. HLT on x86, WFI on arm, etc... If halt
+ * polling is enabled, busy wait for a short time before blocking to avoid the
+ * expensive block+unblock sequence if a wake event arrives soon after the vCPU
+ * is halted.
+ */
void kvm_vcpu_halt(struct kvm_vcpu *vcpu)
{
bool halt_poll_allowed = !kvm_arch_no_poll(vcpu);
@@ -3245,21 +3279,7 @@ void kvm_vcpu_halt(struct kvm_vcpu *vcpu)
} while (kvm_vcpu_can_poll(cur, stop));
}
- kvm_arch_vcpu_blocking(vcpu);
-
- prepare_to_rcuwait(&vcpu->wait);
- for (;;) {
- set_current_state(TASK_INTERRUPTIBLE);
-
- if (kvm_vcpu_check_block(vcpu) < 0)
- break;
-
- waited = true;
- schedule();
- }
- finish_rcuwait(&vcpu->wait);
-
- kvm_arch_vcpu_unblocking(vcpu);
+ waited = kvm_vcpu_block(vcpu);
cur = ktime_get();
if (waited) {
--
2.33.0.685.g46640cef36-goog
next prev parent reply other threads:[~2021-09-25 0:56 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-25 0:55 [PATCH 00/14] KVM: Halt-polling fixes, cleanups and a new stat Sean Christopherson
2021-09-25 0:55 ` [PATCH 01/14] KVM: s390: Ensure kvm_arch_no_poll() is read once when blocking vCPU Sean Christopherson
2021-09-27 6:54 ` Christian Borntraeger
2021-09-25 0:55 ` [PATCH 02/14] KVM: Update halt-polling stats if and only if halt-polling was attempted Sean Christopherson
2021-09-28 18:57 ` David Matlack
2021-09-25 0:55 ` [PATCH 03/14] KVM: Refactor and document halt-polling stats update helper Sean Christopherson
2021-09-28 19:01 ` David Matlack
2021-09-25 0:55 ` [PATCH 04/14] KVM: Reconcile discrepancies in halt-polling stats Sean Christopherson
2021-09-28 21:26 ` David Matlack
2021-09-25 0:55 ` [PATCH 05/14] KVM: s390: Clear valid_wakeup in kvm_s390_handle_wait(), not in arch hook Sean Christopherson
2021-09-27 6:58 ` Christian Borntraeger
2021-09-25 0:55 ` [PATCH 06/14] KVM: Drop obsolete kvm_arch_vcpu_block_finish() Sean Christopherson
2021-09-27 6:58 ` Christian Borntraeger
2021-09-28 21:28 ` David Matlack
2021-09-25 0:55 ` [PATCH 07/14] KVM: Don't block+unblock when halt-polling is successful Sean Christopherson
2021-09-25 9:50 ` Marc Zyngier
2021-09-26 6:27 ` Paolo Bonzini
2021-09-26 9:02 ` Marc Zyngier
2021-09-27 17:28 ` Sean Christopherson
2021-09-28 9:24 ` Marc Zyngier
2021-09-28 16:21 ` Sean Christopherson
2021-09-30 9:36 ` Marc Zyngier
2021-09-25 0:55 ` [PATCH 08/14] KVM: x86: Tweak halt emulation helper names to free up kvm_vcpu_halt() Sean Christopherson
2021-09-28 21:59 ` David Matlack
2021-09-25 0:55 ` [PATCH 09/14] KVM: Rename kvm_vcpu_block() => kvm_vcpu_halt() Sean Christopherson
2021-09-27 7:06 ` Christian Borntraeger
2021-09-28 22:01 ` David Matlack
2021-09-25 0:55 ` Sean Christopherson [this message]
2021-09-27 7:41 ` [PATCH 10/14] KVM: Split out a kvm_vcpu_block() helper from kvm_vcpu_halt() Christian Borntraeger
2021-09-28 22:03 ` David Matlack
2021-09-25 0:55 ` [PATCH 11/14] KVM: stats: Add stat to detect if vcpu is currently blocking Sean Christopherson
2021-09-28 22:04 ` David Matlack
2021-09-25 0:55 ` [PATCH 12/14] KVM: Don't redo ktime_get() when calculating halt-polling stop/deadline Sean Christopherson
2021-09-28 22:08 ` David Matlack
2021-09-25 0:55 ` [PATCH 13/14] KVM: x86: Directly block (instead of "halting") UNINITIALIZED vCPUs Sean Christopherson
2021-09-28 22:12 ` David Matlack
2021-09-25 0:55 ` [PATCH 14/14] KVM: x86: Invoke kvm_vcpu_block() directly for non-HALTED wait states Sean Christopherson
2021-09-28 22:14 ` David Matlack
2021-09-27 7:22 ` disabling halt polling broken? (was Re: [PATCH 00/14] KVM: Halt-polling fixes, cleanups and a new stat) Christian Borntraeger
2021-09-27 14:59 ` Sean Christopherson
2021-09-27 15:03 ` Paolo Bonzini
2021-09-27 15:15 ` Sean Christopherson
2021-09-27 15:16 ` Christian Borntraeger
2021-09-27 16:58 ` David Matlack
2021-09-29 6:56 ` Christian Borntraeger
2021-09-27 17:24 ` Paolo Bonzini
2021-09-27 17:33 ` Sean Christopherson
2022-11-15 3:28 ` wangyanan (Y)
2022-11-16 17:19 ` David Matlack
2022-11-18 2:29 ` wangyanan (Y)
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