Commit 708f799d authored by Michal Luczaj's avatar Michal Luczaj Committed by Sean Christopherson
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KVM: x86: Optimize kvm->lock and SRCU interaction (KVM_X86_SET_MSR_FILTER) 



Reduce time spent holding kvm->lock: unlock mutex before calling
synchronize_srcu().  There is no need to hold kvm->lock until all vCPUs
have been kicked, KVM only needs to guarantee that all vCPUs will switch
to the new filter before exiting to userspace.

Suggested-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarMichal Luczaj <mhal@rbox.co>
Link: https://lore.kernel.org/r/20230107001256.2365304-3-mhal@rbox.co


[sean: expand changelog]
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 95744a90

arch/x86/kvm/x86.c

+1 −1
Original line number Diff line number Diff line
@@ -6497,12 +6497,12 @@ static int kvm_vm_ioctl_set_msr_filter(struct kvm *kvm, 
	old_filter = srcu_dereference_check(kvm->arch.msr_filter, &kvm->srcu, 1);



	rcu_assign_pointer(kvm->arch.msr_filter, new_filter);

	mutex_unlock(&kvm->lock);

	synchronize_srcu(&kvm->srcu);



	kvm_free_msr_filter(old_filter);



	kvm_make_all_cpus_request(kvm, KVM_REQ_MSR_FILTER_CHANGED);

	mutex_unlock(&kvm->lock);



	return 0;

}