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Peter Anvin" Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v1 2/3] Revert "x86: kvm: rate-limit global clock updates" Date: Tue, 19 Aug 2025 23:20:26 +0800 Message-ID: <20250819152027.1687487-3-lei.chen@smartx.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20250819152027.1687487-1-lei.chen@smartx.com> References: <20250819152027.1687487-1-lei.chen@smartx.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This reverts commit 7e44e4495a398eb553ce561f29f9148f40a3448f. Commit 7e44e4495a39 ("x86: kvm: rate-limit global clock updates") intends to use a kvmclock_update_work to sync ntp corretion across all vcpus kvmclock, which is based on commit 0061d53daf26f ("KVM: x86: limit difference between kvmclock updates") Since kvmclock has been switched to mono raw, this commit can be reverted. Signed-off-by: Lei Chen --- arch/x86/include/asm/kvm_host.h | 1 - arch/x86/kvm/x86.c | 29 ++++------------------------- 2 files changed, 4 insertions(+), 26 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_hos= t.h index e41e4fe91f5e..0a1165f40ff1 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1435,7 +1435,6 @@ struct kvm_arch { bool use_master_clock; u64 master_kernel_ns; u64 master_cycle_now; - struct delayed_work kvmclock_update_work; =20 #ifdef CONFIG_KVM_HYPERV struct kvm_hv hyperv; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 399045a384d4..d526e9e285f1 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3404,22 +3404,14 @@ uint64_t kvm_get_wall_clock_epoch(struct kvm *kvm) * the others. * * So in those cases, request a kvmclock update for all vcpus. - * We need to rate-limit these requests though, as they can - * considerably slow guests that have a large number of vcpus. - * The time for a remote vcpu to update its kvmclock is bound - * by the delay we use to rate-limit the updates. + * The worst case for a remote vcpu to update its kvmclock + * is then bounded by maximum nohz sleep latency. */ - -#define KVMCLOCK_UPDATE_DELAY msecs_to_jiffies(100) - -static void kvmclock_update_fn(struct work_struct *work) +static void kvm_gen_kvmclock_update(struct kvm_vcpu *v) { unsigned long i; - struct delayed_work *dwork =3D to_delayed_work(work); - struct kvm_arch *ka =3D container_of(dwork, struct kvm_arch, - kvmclock_update_work); - struct kvm *kvm =3D container_of(ka, struct kvm, arch); struct kvm_vcpu *vcpu; + struct kvm *kvm =3D v->kvm; =20 kvm_for_each_vcpu(i, vcpu, kvm) { kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); @@ -3427,15 +3419,6 @@ static void kvmclock_update_fn(struct work_struct *w= ork) } } =20 -static void kvm_gen_kvmclock_update(struct kvm_vcpu *v) -{ - struct kvm *kvm =3D v->kvm; - - kvm_make_request(KVM_REQ_CLOCK_UPDATE, v); - schedule_delayed_work(&kvm->arch.kvmclock_update_work, - KVMCLOCK_UPDATE_DELAY); -} - /* These helpers are safe iff @msr is known to be an MCx bank MSR. */ static bool is_mci_control_msr(u32 msr) { @@ -12698,8 +12681,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long= type) kvm->arch.hv_root_tdp =3D INVALID_PAGE; #endif =20 - INIT_DELAYED_WORK(&kvm->arch.kvmclock_update_work, kvmclock_update_fn); - kvm_apicv_init(kvm); kvm_hv_init_vm(kvm); kvm_xen_init_vm(kvm); @@ -12806,8 +12787,6 @@ void kvm_arch_pre_destroy_vm(struct kvm *kvm) * is unsafe, i.e. will lead to use-after-free. The PIT also needs to * be stopped before IRQ routing is freed. */ - cancel_delayed_work_sync(&kvm->arch.kvmclock_update_work); - #ifdef CONFIG_KVM_IOAPIC kvm_free_pit(kvm); #endif --=20 2.44.0