From c2c647f91aec192f45f0849c225f134183cf4e90 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini <pbonzini@redhat.com> Date: Thu, 25 Mar 2021 14:05:11 -0400 Subject: [PATCH] KVM: x86: reduce pvclock_gtod_sync_lock critical sections There is no need to include changes to vcpu->requests into the pvclock_gtod_sync_lock critical section. The changes to the shared data structures (in pvclock_update_vm_gtod_copy) already occur under the lock. Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/kvm/x86.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index f7d12fca397b9f..2301623d3c53e7 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2561,10 +2561,12 @@ static void kvm_gen_update_masterclock(struct kvm *kvm) kvm_hv_invalidate_tsc_page(kvm); - spin_lock(&ka->pvclock_gtod_sync_lock); kvm_make_mclock_inprogress_request(kvm); + /* no guest entries from this point */ + spin_lock(&ka->pvclock_gtod_sync_lock); pvclock_update_vm_gtod_copy(kvm); + spin_unlock(&ka->pvclock_gtod_sync_lock); kvm_for_each_vcpu(i, vcpu, kvm) kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); @@ -2572,8 +2574,6 @@ static void kvm_gen_update_masterclock(struct kvm *kvm) /* guest entries allowed */ kvm_for_each_vcpu(i, vcpu, kvm) kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu); - - spin_unlock(&ka->pvclock_gtod_sync_lock); #endif } @@ -7739,16 +7739,14 @@ static void kvm_hyperv_tsc_notifier(void) struct kvm_arch *ka = &kvm->arch; spin_lock(&ka->pvclock_gtod_sync_lock); - pvclock_update_vm_gtod_copy(kvm); + spin_unlock(&ka->pvclock_gtod_sync_lock); kvm_for_each_vcpu(cpu, vcpu, kvm) kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); kvm_for_each_vcpu(cpu, vcpu, kvm) kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu); - - spin_unlock(&ka->pvclock_gtod_sync_lock); } mutex_unlock(&kvm_lock); } -- GitLab