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 4/6] KVM: x86: Take the pvclock sync lock behind the tsc_write_lock
Date: Mon, 16 Aug 2021 00:11:28 +0000 [thread overview]
Message-ID: <20210816001130.3059564-5-oupton@google.com> (raw)
In-Reply-To: <20210816001130.3059564-1-oupton@google.com>
A later change requires that the pvclock sync lock be taken while
holding the tsc_write_lock. Change the locking in kvm_synchronize_tsc()
to align with the requirement to isolate the locking change to its own
commit.
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: Oliver Upton <oupton@google.com>
---
Documentation/virt/kvm/locking.rst | 11 +++++++++++
arch/x86/kvm/x86.c | 2 +-
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/Documentation/virt/kvm/locking.rst b/Documentation/virt/kvm/locking.rst
index 8138201efb09..0bf346adac2a 100644
--- a/Documentation/virt/kvm/locking.rst
+++ b/Documentation/virt/kvm/locking.rst
@@ -36,6 +36,9 @@ On x86:
holding kvm->arch.mmu_lock (typically with ``read_lock``, otherwise
there's no need to take kvm->arch.tdp_mmu_pages_lock at all).
+- kvm->arch.tsc_write_lock is taken outside
+ kvm->arch.pvclock_gtod_sync_lock
+
Everything else is a leaf: no other lock is taken inside the critical
sections.
@@ -222,6 +225,14 @@ time it will be set using the Dirty tracking mechanism described above.
:Comment: 'raw' because hardware enabling/disabling must be atomic /wrt
migration.
+:Name: kvm_arch::pvclock_gtod_sync_lock
+:Type: raw_spinlock_t
+:Arch: x86
+:Protects: kvm_arch::{cur_tsc_generation,cur_tsc_nsec,cur_tsc_write,
+ cur_tsc_offset,nr_vcpus_matched_tsc}
+:Comment: 'raw' because updating the kvm master clock must not be
+ preempted.
+
:Name: kvm_arch::tsc_write_lock
:Type: raw_spinlock
:Arch: x86
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b1e9a4885be6..f1434cd388b9 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2533,7 +2533,6 @@ static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 data)
vcpu->arch.this_tsc_write = kvm->arch.cur_tsc_write;
kvm_vcpu_write_tsc_offset(vcpu, offset);
- raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
spin_lock_irqsave(&kvm->arch.pvclock_gtod_sync_lock, flags);
if (!matched) {
@@ -2544,6 +2543,7 @@ static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 data)
kvm_track_tsc_matching(vcpu);
spin_unlock_irqrestore(&kvm->arch.pvclock_gtod_sync_lock, flags);
+ raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
}
static inline void adjust_tsc_offset_guest(struct kvm_vcpu *vcpu,
--
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 ` Oliver Upton [this message]
2021-09-02 19:22 ` [PATCH v7 4/6] KVM: x86: Take the pvclock sync lock behind the tsc_write_lock Sean Christopherson
2021-08-16 0:11 ` [PATCH v7 5/6] KVM: x86: Refactor tsc synchronization code Oliver Upton
2021-09-02 19:21 ` 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
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