From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>
Subject: [PATCH RESEND v2] KVM: X86: Implement PV sched yield hypercall
Date: Tue, 28 May 2019 10:15:52 +0800 [thread overview]
Message-ID: <1559009752-8536-1-git-send-email-wanpengli@tencent.com> (raw)
In-Reply-To: <1559004795-19927-3-git-send-email-wanpengli@tencent.com>
From: Wanpeng Li <wanpengli@tencent.com>
The target vCPUs are in runnable state after vcpu_kick and suitable
as a yield target. This patch implements the sched yield hypercall.
17% performance increase of ebizzy benchmark can be observed in an
over-subscribe environment. (w/ kvm-pv-tlb disabled, testing TLB flush
call-function IPI-many since call-function is not easy to be trigged
by userspace workload).
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
arch/x86/kvm/x86.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e7e57de..2f9ec08 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7172,6 +7172,28 @@ void kvm_vcpu_deactivate_apicv(struct kvm_vcpu *vcpu)
kvm_x86_ops->refresh_apicv_exec_ctrl(vcpu);
}
+void kvm_sched_yield(struct kvm *kvm, u64 dest_id)
+{
+ struct kvm_vcpu *target;
+ struct kvm_apic_map *map;
+
+ rcu_read_lock();
+ map = rcu_dereference(kvm->arch.apic_map);
+
+ if (unlikely(!map))
+ goto out;
+
+ if (map->phys_map[dest_id]->vcpu) {
+ target = map->phys_map[dest_id]->vcpu;
+ rcu_read_unlock();
+ kvm_vcpu_yield_to(target);
+ }
+
+out:
+ if (!target)
+ rcu_read_unlock();
+}
+
int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
{
unsigned long nr, a0, a1, a2, a3, ret;
@@ -7218,6 +7240,10 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
case KVM_HC_SEND_IPI:
ret = kvm_pv_send_ipi(vcpu->kvm, a0, a1, a2, a3, op_64_bit);
break;
+ case KVM_HC_SCHED_YIELD:
+ kvm_sched_yield(vcpu->kvm, a0);
+ ret = 0;
+ break;
default:
ret = -KVM_ENOSYS;
break;
--
2.7.4
next prev parent reply other threads:[~2019-05-28 2:16 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-28 0:53 [PATCH v2 0/3] KVM: Yield to IPI target if necessary Wanpeng Li
2019-05-28 0:53 ` [PATCH v2 1/3] KVM: X86: Implement PV sched yield in linux guest Wanpeng Li
2019-05-28 0:53 ` [PATCH v2 2/3] KVM: X86: Implement PV sched yield hypercall Wanpeng Li
2019-05-28 2:15 ` Wanpeng Li [this message]
2019-05-28 6:08 ` [PATCH RESEND v2] " kbuild test robot
2019-05-28 6:14 ` Wanpeng Li
2019-05-28 7:23 ` kbuild test robot
2019-05-28 7:50 ` [PATCH RESEND v2 0/3] KVM: Yield to IPI target if necessary Wanpeng Li
2019-05-28 7:50 ` [PATCH RESEND v2 1/3] KVM: X86: Implement PV sched yield in linux guest Wanpeng Li
2019-05-28 7:50 ` [PATCH RESEND v2 2/3] KVM: X86: Implement PV sched yield hypercall Wanpeng Li
2019-05-28 7:50 ` [PATCH RESEND v2 3/3] KVM: X86: Expose PV_SCHED_YIELD CPUID feature bit to guest Wanpeng Li
2019-05-28 9:11 ` [PATCH v2 2/3] KVM: X86: Implement PV sched yield hypercall Christian Borntraeger
2019-05-28 9:57 ` Wanpeng Li
2019-05-29 12:28 ` Liran Alon
2019-05-30 1:09 ` Wanpeng Li
2019-05-28 0:53 ` [PATCH v2 3/3] KVM: X86: Expose PV_SCHED_YIELD CPUID feature bit to guest Wanpeng Li
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1559009752-8536-1-git-send-email-wanpengli@tencent.com \
--to=kernellwp@gmail.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=rkrcmar@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).