From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: 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>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Michael Tokarev <mjt@tls.msk.ru>,
Christian Borntraeger <borntraeger@de.ibm.com>
Subject: [PATCH v3 3/9] KVM: x86: Defer tick-based accounting 'til after IRQ handling
Date: Thu, 15 Apr 2021 15:21:00 -0700 [thread overview]
Message-ID: <20210415222106.1643837-4-seanjc@google.com> (raw)
In-Reply-To: <20210415222106.1643837-1-seanjc@google.com>
From: Wanpeng Li <wanpengli@tencent.com>
When using tick-based accounting, defer the call to account guest time
until after servicing any IRQ(s) that happened in the guest or
immediately after VM-Exit. Tick-based accounting of vCPU time relies on
PF_VCPU being set when the tick IRQ handler runs, and IRQs are blocked
throughout {svm,vmx}_vcpu_enter_exit().
This fixes a bug[*] where reported guest time remains '0', even when
running an infinite loop in the guest.
[*] https://bugzilla.kernel.org/show_bug.cgi?id=209831
Fixes: 87fa7f3e98a131 ("x86/kvm: Move context tracking where it belongs")
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Michael Tokarev <mjt@tls.msk.ru>
Cc: stable@vger.kernel.org#v5.9-rc1+
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/svm/svm.c | 13 ++++++++++---
arch/x86/kvm/vmx/vmx.c | 13 ++++++++++---
arch/x86/kvm/x86.c | 8 ++++++++
3 files changed, 28 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 48b396f33bee..bb2aa0dde7c5 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3750,17 +3750,24 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
* have them in state 'on' as recorded before entering guest mode.
* Same as enter_from_user_mode().
*
- * guest_exit_irqoff() restores host context and reinstates RCU if
- * enabled and required.
+ * context_tracking_guest_exit_irqoff() restores host context and
+ * reinstates RCU if enabled and required.
*
* This needs to be done before the below as native_read_msr()
* contains a tracepoint and x86_spec_ctrl_restore_host() calls
* into world and some more.
*/
lockdep_hardirqs_off(CALLER_ADDR0);
- guest_exit_irqoff();
+ context_tracking_guest_exit_irqoff();
instrumentation_begin();
+ /*
+ * Account guest time when precise accounting based on context tracking
+ * is enabled. Tick based accounting is deferred until after IRQs that
+ * occurred within the VM-Enter/VM-Exit "window" are handled.
+ */
+ if (vtime_accounting_enabled_this_cpu())
+ vtime_account_guest_exit();
trace_hardirqs_off_finish();
instrumentation_end();
}
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index c05e6e2854b5..5ae9dc197048 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6639,17 +6639,24 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
* have them in state 'on' as recorded before entering guest mode.
* Same as enter_from_user_mode().
*
- * guest_exit_irqoff() restores host context and reinstates RCU if
- * enabled and required.
+ * context_tracking_guest_exit_irqoff() restores host context and
+ * reinstates RCU if enabled and required.
*
* This needs to be done before the below as native_read_msr()
* contains a tracepoint and x86_spec_ctrl_restore_host() calls
* into world and some more.
*/
lockdep_hardirqs_off(CALLER_ADDR0);
- guest_exit_irqoff();
+ context_tracking_guest_exit_irqoff();
instrumentation_begin();
+ /*
+ * Account guest time when precise accounting based on context tracking
+ * is enabled. Tick based accounting is deferred until after IRQs that
+ * occurred within the VM-Enter/VM-Exit "window" are handled.
+ */
+ if (vtime_accounting_enabled_this_cpu())
+ vtime_account_guest_exit();
trace_hardirqs_off_finish();
instrumentation_end();
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 16fb39503296..e4d475df1d4a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9230,6 +9230,14 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
local_irq_disable();
kvm_after_interrupt(vcpu);
+ /*
+ * When using tick-based accounting, wait until after servicing IRQs to
+ * account guest time so that any ticks that occurred while running the
+ * guest are properly accounted to the guest.
+ */
+ if (!vtime_accounting_enabled_this_cpu())
+ vtime_account_guest_exit();
+
if (lapic_in_kernel(vcpu)) {
s64 delta = vcpu->arch.apic->lapic_timer.advance_expire_delta;
if (delta != S64_MIN) {
--
2.31.1.368.gbe11c130af-goog
next prev parent reply other threads:[~2021-04-15 22:21 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-15 22:20 [PATCH v3 0/9] KVM: Fix tick-based accounting for x86 guests Sean Christopherson
2021-04-15 22:20 ` [PATCH v3 1/9] context_tracking: Move guest exit context tracking to separate helpers Sean Christopherson
2021-04-20 18:48 ` Christian Borntraeger
2021-04-21 10:57 ` Frederic Weisbecker
2021-04-15 22:20 ` [PATCH v3 2/9] context_tracking: Move guest exit vtime accounting " Sean Christopherson
2021-04-20 18:48 ` Christian Borntraeger
2021-04-15 22:21 ` Sean Christopherson [this message]
2021-04-20 23:14 ` [PATCH v3 3/9] KVM: x86: Defer tick-based accounting 'til after IRQ handling Frederic Weisbecker
2021-04-20 23:26 ` Sean Christopherson
2021-04-21 10:11 ` Frederic Weisbecker
2021-04-21 12:19 ` Frederic Weisbecker
2021-04-28 22:38 ` Sean Christopherson
2021-04-21 10:07 ` Frederic Weisbecker
2021-04-15 22:21 ` [PATCH v3 4/9] sched/vtime: Move vtime accounting external declarations above inlines Sean Christopherson
2021-04-21 7:02 ` Christian Borntraeger
2021-04-15 22:21 ` [PATCH v3 5/9] sched/vtime: Move guest enter/exit vtime accounting to vtime.h Sean Christopherson
2021-04-15 22:21 ` [PATCH v3 6/9] context_tracking: Consolidate guest enter/exit wrappers Sean Christopherson
2021-04-15 22:21 ` [PATCH v3 7/9] context_tracking: KVM: Move guest enter/exit wrappers to KVM's domain Sean Christopherson
2021-04-21 7:10 ` Christian Borntraeger
2021-04-15 22:21 ` [PATCH v3 8/9] KVM: x86: Consolidate guest enter/exit logic to common helpers Sean Christopherson
2021-04-15 22:21 ` [PATCH v3 9/9] KVM: Move instrumentation-safe annotations for enter/exit to x86 code Sean Christopherson
2021-04-21 8:09 ` Christian Borntraeger
2021-04-22 14:38 ` Sven Schnelle
2021-04-23 9:32 ` Vasily Gorbik
2021-04-20 23:33 ` [PATCH v3 0/9] KVM: Fix tick-based accounting for x86 guests Frederic Weisbecker
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=20210415222106.1643837-4-seanjc@google.com \
--to=seanjc@google.com \
--cc=borntraeger@de.ibm.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mjt@tls.msk.ru \
--cc=pbonzini@redhat.com \
--cc=tglx@linutronix.de \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.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).