Commit 446fcce2 authored by Lei Chen's avatar Lei Chen Committed by Sean Christopherson
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Revert "x86: kvm: rate-limit global clock updates" 



This reverts commit 7e44e449.

Commit 7e44e449 ("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 0061d53d
("KVM: x86: limit difference between kvmclock updates")

Since kvmclock has been switched to mono raw, this commit can be
reverted.

Signed-off-by: default avatarLei Chen <lei.chen@smartx.com>
Link: https://patch.msgid.link/20250819152027.1687487-3-lei.chen@smartx.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 43ddbf16

arch/x86/include/asm/kvm_host.h

+0 −1
Original line number Diff line number Diff line
@@ -1456,7 +1456,6 @@ struct kvm_arch { 
	bool use_master_clock;

	u64 master_kernel_ns;

	u64 master_cycle_now;

	struct delayed_work kvmclock_update_work;



#ifdef CONFIG_KVM_HYPERV

	struct kvm_hv hyperv;

arch/x86/kvm/x86.c

+4 −25
Original line number Diff line number Diff line
@@ -3523,22 +3523,14 @@ 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 = to_delayed_work(work);

	struct kvm_arch *ka = container_of(dwork, struct kvm_arch,

					   kvmclock_update_work);

	struct kvm *kvm = container_of(ka, struct kvm, arch);

	struct kvm_vcpu *vcpu;

	struct kvm *kvm = v->kvm;



	kvm_for_each_vcpu(i, vcpu, kvm) {

		kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
@@ -3546,15 +3538,6 @@ static void kvmclock_update_fn(struct work_struct *work) 
	}

}



static void kvm_gen_kvmclock_update(struct kvm_vcpu *v)

{

	struct kvm *kvm = 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)

{
@@ -13163,8 +13146,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) 
	kvm->arch.hv_root_tdp = INVALID_PAGE;

#endif



	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);
@@ -13271,8 +13252,6 @@ 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