linux-kernel - Re: [PATCH RFC 1/4] KVM: Provide kvm_flush_remote_tlbs

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Message-ID: <c83a9193-d91b-0f64-d0c9-40b2bad86bdc@redhat.com>
Date:   Wed, 12 Feb 2020 14:33:02 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Peter Xu <peterx@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        linux-mips@...r.kernel.org, Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: Re: [PATCH RFC 1/4] KVM: Provide kvm_flush_remote_tlbs_common()

On 07/02/20 23:35, Peter Xu wrote:
> It's exactly kvm_flush_remote_tlbs() now but a internal wrapper of the
> common code path.  With this, an arch can then optionally select
> CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL=y and will be able to use the
> common flushing code.
> 
> Signed-off-by: Peter Xu <peterx@...hat.com>

Slightly more efficient, making it an inline function:

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index e89eb67356cb..f92180eeffc6 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -802,9 +802,18 @@ int kvm_vcpu_write_guest(struct kvm_vcpu *vcpu, gpa_t gpa, const void *data,
 int kvm_vcpu_yield_to(struct kvm_vcpu *target);
 void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu, bool usermode_vcpu_not_eligible);
 
-void kvm_flush_remote_tlbs(struct kvm *kvm);
+void kvm_flush_remote_tlbs_common(struct kvm *kvm);
 void kvm_reload_remote_mmus(struct kvm *kvm);
 
+#ifdef CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL
+void kvm_flush_remote_tlbs(struct kvm *kvm);
+#else
+static inline void kvm_flush_remote_tlbs(struct kvm *kvm)
+{
+	kvm_flush_remote_tlbs_common(kvm);
+}
+#endif
+
 bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req,
 				 unsigned long *vcpu_bitmap, cpumask_var_t tmp);
 bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 70f03ce0e5c1..027259af883e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -303,8 +303,7 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req)
 	return called;
 }
 
-#ifndef CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL
-void kvm_flush_remote_tlbs(struct kvm *kvm)
+void kvm_flush_remote_tlbs_common(struct kvm *kvm)
 {
 	/*
 	 * Read tlbs_dirty before setting KVM_REQ_TLB_FLUSH in
@@ -328,8 +327,7 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
 		++kvm->stat.remote_tlb_flush;
 	cmpxchg(&kvm->tlbs_dirty, dirty_count, 0);
 }
-EXPORT_SYMBOL_GPL(kvm_flush_remote_tlbs);
-#endif
+EXPORT_SYMBOL_GPL(kvm_flush_remote_tlbs_common);
 
 void kvm_reload_remote_mmus(struct kvm *kvm)
 {