From: Oliver Upton <oupton@google.com>
To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Marc Zyngier <maz@kernel.org>, Peter Shier <pshier@google.com>,
Jim Mattson <jmattson@google.com>,
David Matlack <dmatlack@google.com>,
Ricardo Koller <ricarkol@google.com>,
Jing Zhang <jingzhangos@google.com>,
Raghavendra Rao Anata <rananta@google.com>,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
linux-arm-kernel@lists.infradead.org,
Andrew Jones <drjones@redhat.com>, Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Oliver Upton <oupton@google.com>
Subject: [PATCH v7 5/6] KVM: x86: Refactor tsc synchronization code
Date: Mon, 16 Aug 2021 00:11:29 +0000 [thread overview]
Message-ID: <20210816001130.3059564-6-oupton@google.com> (raw)
In-Reply-To: <20210816001130.3059564-1-oupton@google.com>
Refactor kvm_synchronize_tsc to make a new function that allows callers
to specify TSC parameters (offset, value, nanoseconds, etc.) explicitly
for the sake of participating in TSC synchronization.
Signed-off-by: Oliver Upton <oupton@google.com>
---
arch/x86/kvm/x86.c | 105 ++++++++++++++++++++++++++-------------------
1 file changed, 61 insertions(+), 44 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f1434cd388b9..9d0445527dad 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2447,13 +2447,71 @@ static inline bool kvm_check_tsc_unstable(void)
return check_tsc_unstable();
}
+/*
+ * Infers attempts to synchronize the guest's tsc from host writes. Sets the
+ * offset for the vcpu and tracks the TSC matching generation that the vcpu
+ * participates in.
+ */
+static void __kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 offset, u64 tsc,
+ u64 ns, bool matched)
+{
+ struct kvm *kvm = vcpu->kvm;
+ bool already_matched;
+
+ lockdep_assert_held(&kvm->arch.tsc_write_lock);
+
+ already_matched =
+ (vcpu->arch.this_tsc_generation == kvm->arch.cur_tsc_generation);
+
+ /*
+ * We track the most recent recorded KHZ, write and time to
+ * allow the matching interval to be extended at each write.
+ */
+ kvm->arch.last_tsc_nsec = ns;
+ kvm->arch.last_tsc_write = tsc;
+ kvm->arch.last_tsc_khz = vcpu->arch.virtual_tsc_khz;
+
+ vcpu->arch.last_guest_tsc = tsc;
+
+ /* Keep track of which generation this VCPU has synchronized to */
+ vcpu->arch.this_tsc_generation = kvm->arch.cur_tsc_generation;
+ vcpu->arch.this_tsc_nsec = kvm->arch.cur_tsc_nsec;
+ vcpu->arch.this_tsc_write = kvm->arch.cur_tsc_write;
+
+ kvm_vcpu_write_tsc_offset(vcpu, offset);
+
+ if (!matched) {
+ /*
+ * We split periods of matched TSC writes into generations.
+ * For each generation, we track the original measured
+ * nanosecond time, offset, and write, so if TSCs are in
+ * sync, we can match exact offset, and if not, we can match
+ * exact software computation in compute_guest_tsc()
+ *
+ * These values are tracked in kvm->arch.cur_xxx variables.
+ */
+ kvm->arch.cur_tsc_generation++;
+ kvm->arch.cur_tsc_nsec = ns;
+ kvm->arch.cur_tsc_write = tsc;
+ kvm->arch.cur_tsc_offset = offset;
+
+ spin_lock(&kvm->arch.pvclock_gtod_sync_lock);
+ kvm->arch.nr_vcpus_matched_tsc = 0;
+ } else if (!already_matched) {
+ spin_lock(&kvm->arch.pvclock_gtod_sync_lock);
+ kvm->arch.nr_vcpus_matched_tsc++;
+ }
+
+ kvm_track_tsc_matching(vcpu);
+ spin_unlock(&kvm->arch.pvclock_gtod_sync_lock);
+}
+
static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 data)
{
struct kvm *kvm = vcpu->kvm;
u64 offset, ns, elapsed;
unsigned long flags;
- bool matched;
- bool already_matched;
+ bool matched = false;
bool synchronizing = false;
raw_spin_lock_irqsave(&kvm->arch.tsc_write_lock, flags);
@@ -2499,50 +2557,9 @@ static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 data)
offset = kvm_compute_l1_tsc_offset(vcpu, data);
}
matched = true;
- already_matched = (vcpu->arch.this_tsc_generation == kvm->arch.cur_tsc_generation);
- } else {
- /*
- * We split periods of matched TSC writes into generations.
- * For each generation, we track the original measured
- * nanosecond time, offset, and write, so if TSCs are in
- * sync, we can match exact offset, and if not, we can match
- * exact software computation in compute_guest_tsc()
- *
- * These values are tracked in kvm->arch.cur_xxx variables.
- */
- kvm->arch.cur_tsc_generation++;
- kvm->arch.cur_tsc_nsec = ns;
- kvm->arch.cur_tsc_write = data;
- kvm->arch.cur_tsc_offset = offset;
- matched = false;
}
- /*
- * We also track th most recent recorded KHZ, write and time to
- * allow the matching interval to be extended at each write.
- */
- kvm->arch.last_tsc_nsec = ns;
- kvm->arch.last_tsc_write = data;
- kvm->arch.last_tsc_khz = vcpu->arch.virtual_tsc_khz;
-
- vcpu->arch.last_guest_tsc = data;
-
- /* Keep track of which generation this VCPU has synchronized to */
- vcpu->arch.this_tsc_generation = kvm->arch.cur_tsc_generation;
- vcpu->arch.this_tsc_nsec = kvm->arch.cur_tsc_nsec;
- vcpu->arch.this_tsc_write = kvm->arch.cur_tsc_write;
-
- kvm_vcpu_write_tsc_offset(vcpu, offset);
-
- spin_lock_irqsave(&kvm->arch.pvclock_gtod_sync_lock, flags);
- if (!matched) {
- kvm->arch.nr_vcpus_matched_tsc = 0;
- } else if (!already_matched) {
- kvm->arch.nr_vcpus_matched_tsc++;
- }
-
- kvm_track_tsc_matching(vcpu);
- spin_unlock_irqrestore(&kvm->arch.pvclock_gtod_sync_lock, flags);
+ __kvm_synchronize_tsc(vcpu, offset, data, ns, matched);
raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
}
--
2.33.0.rc1.237.g0d66db33f3-goog
next prev parent reply other threads:[~2021-08-16 0:11 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-16 0:11 [PATCH v7 0/6] KVM: x86: Add idempotent controls for migrating system counter state Oliver Upton
2021-08-16 0:11 ` [PATCH v7 1/6] KVM: x86: Fix potential race in KVM_GET_CLOCK Oliver Upton
2021-08-19 18:24 ` Marcelo Tosatti
2021-08-20 18:22 ` Oliver Upton
2021-08-16 0:11 ` [PATCH v7 2/6] KVM: x86: Create helper methods for KVM_{GET,SET}_CLOCK ioctls Oliver Upton
2021-08-16 0:11 ` [PATCH v7 3/6] KVM: x86: Report host tsc and realtime values in KVM_GET_CLOCK Oliver Upton
2021-08-20 12:46 ` Marcelo Tosatti
2021-09-24 8:30 ` Paolo Bonzini
2021-08-16 0:11 ` [PATCH v7 4/6] KVM: x86: Take the pvclock sync lock behind the tsc_write_lock Oliver Upton
2021-09-02 19:22 ` Sean Christopherson
2021-08-16 0:11 ` Oliver Upton [this message]
2021-09-02 19:21 ` [PATCH v7 5/6] KVM: x86: Refactor tsc synchronization code Sean Christopherson
2021-09-02 19:41 ` Oliver Upton
2021-09-24 9:28 ` Paolo Bonzini
2021-08-16 0:11 ` [PATCH v7 6/6] KVM: x86: Expose TSC offset controls to userspace Oliver Upton
2021-08-23 20:56 ` Oliver Upton
2021-08-26 12:48 ` Marcelo Tosatti
2021-08-26 20:27 ` Oliver Upton
2021-09-02 19:23 ` [PATCH v7 0/6] KVM: x86: Add idempotent controls for migrating system counter state Sean Christopherson
2021-09-02 19:45 ` Oliver Upton
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=20210816001130.3059564-6-oupton@google.com \
--to=oupton@google.com \
--cc=alexandru.elisei@arm.com \
--cc=catalin.marinas@arm.com \
--cc=dmatlack@google.com \
--cc=drjones@redhat.com \
--cc=james.morse@arm.com \
--cc=jingzhangos@google.com \
--cc=jmattson@google.com \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=maz@kernel.org \
--cc=pbonzini@redhat.com \
--cc=pshier@google.com \
--cc=rananta@google.com \
--cc=ricarkol@google.com \
--cc=seanjc@google.com \
--cc=suzuki.poulose@arm.com \
--cc=will@kernel.org \
/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).