KVM: x86: Add tlb remote flush callback in kvm_x86_ops.

This patch is to provide a way for platforms to register hv tlb remote
flush callback and this helps to optimize operation of tlb flush
among vcpus for nested virtualization case.

Signed-off-by: Lan Tianyu <Tianyu.Lan@microsoft.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 75ab578..150937e 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -985,6 +985,7 @@ struct kvm_x86_ops {
        void (*set_rflags)(struct kvm_vcpu *vcpu, unsigned long rflags);
 
        void (*tlb_flush)(struct kvm_vcpu *vcpu, bool invalidate_gpa);
+       int  (*tlb_remote_flush)(struct kvm *kvm);
 
        /*
         * Flush any TLB entries associated with the given GVA.
@@ -1145,6 +1146,16 @@ static inline void kvm_arch_free_vm(struct kvm *kvm)
        return kvm_x86_ops->vm_free(kvm);
 }
 
+#define __KVM_HAVE_ARCH_FLUSH_REMOTE_TLB
+static inline int kvm_arch_flush_remote_tlb(struct kvm *kvm)
+{
+       if (kvm_x86_ops->tlb_remote_flush &&
+           !kvm_x86_ops->tlb_remote_flush(kvm))
+               return 0;
+       else
+               return -ENOTSUPP;
+}
+
 int kvm_mmu_module_init(void);
 void kvm_mmu_module_exit(void);
 

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 2840ac7..7c7362d 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -834,6 +834,13 @@ static inline void kvm_arch_free_vm(struct kvm *kvm)
 }
 #endif
 
+#ifndef __KVM_HAVE_ARCH_FLUSH_REMOTE_TLB
+static inline int kvm_arch_flush_remote_tlb(struct kvm *kvm)
+{
+       return -ENOTSUPP;
+}
+#endif
+
 #ifdef __KVM_HAVE_ARCH_NONCOHERENT_DMA
 void kvm_arch_register_noncoherent_dma(struct kvm *kvm);
 void kvm_arch_unregister_noncoherent_dma(struct kvm *kvm);

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8f461e0..74544d2 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -273,7 +273,8 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
         * kvm_make_all_cpus_request() reads vcpu->mode. We reuse that
         * barrier here.
         */
-       if (kvm_make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH))
+       if (!kvm_arch_flush_remote_tlb(kvm)
+           || kvm_make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH))
                ++kvm->stat.remote_tlb_flush;
        cmpxchg(&kvm->tlbs_dirty, dirty_count, 0);
 }