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Subject[PATCH V2 2/5] KVM: Add tlb remote flush callback in kvm_x86_ops.
Date
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>
---
Change since v1:
Add kvm_arch_hv_flush_remote_tlb() to avoid compilation issue
for non-x86 platform.
---
arch/x86/include/asm/kvm_host.h | 11 +++++++++++
include/linux/kvm_host.h | 7 +++++++
virt/kvm/kvm_main.c | 11 ++++++++++-
3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c13cd28d9d1b..d89e4204816c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -973,6 +973,7 @@ 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 (*hv_tlb_remote_flush)(struct kvm *kvm);

void (*run)(struct kvm_vcpu *vcpu);
int (*handle_exit)(struct kvm_vcpu *vcpu);
@@ -1117,6 +1118,16 @@ static inline void kvm_arch_free_vm(struct kvm *kvm)
return kvm_x86_ops->vm_free(kvm);
}

+#define __KVM_HAVE_HV_FLUSH_REMOTE_TLB
+static inline int kvm_arch_hv_flush_remote_tlb(struct kvm *kvm)
+{
+ if (kvm_x86_ops->hv_tlb_remote_flush &&
+ !kvm_x86_ops->hv_tlb_remote_flush(kvm))
+ return 0;
+ else
+ return -EFAULT;
+}
+
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 4ee7bc548a83..0c2c36cb041b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -827,6 +827,13 @@ static inline void kvm_arch_free_vm(struct kvm *kvm)
}
#endif

+#ifndef __KVM_HAVE_HV_FLUSH_REMOTE_TLB
+static inline int kvm_arch_hv_flush_remote_tlb(struct kvm *kvm)
+{
+ return -EFAULT;
+}
+#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 8b47507faab5..c2b5e3273848 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -256,11 +256,20 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req)
#ifndef CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL
void kvm_flush_remote_tlbs(struct kvm *kvm)
{
+ long dirty_count;
+
+ /*
+ * Call kvm_arch_hv_tlb_remote first and go back old way when
+ * return failure.
+ */
+ if (!kvm_arch_hv_flush_remote_tlb(kvm))
+ return;
+
/*
* Read tlbs_dirty before setting KVM_REQ_TLB_FLUSH in
* kvm_make_all_cpus_request.
*/
- long dirty_count = smp_load_acquire(&kvm->tlbs_dirty);
+ dirty_count = smp_load_acquire(&kvm->tlbs_dirty);

/*
* We want to publish modifications to the page tables before reading
--
2.14.3
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