linux-kernel - [PATCH v7 8/9] kvm, mem-hotplug: Add arch specific mmu notifier to handle apic access migration.

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Date:	Sat, 20 Sep 2014 18:47:50 +0800
From:	Tang Chen <tangchen@...fujitsu.com>
To:	<gleb@...nel.org>, <mtosatti@...hat.com>, <nadav.amit@...il.com>,
	<jan.kiszka@....de>, <pbonzini@...hat.com>
CC:	<kvm@...r.kernel.org>, <laijs@...fujitsu.com>,
	<isimatu.yasuaki@...fujitsu.com>, <guz.fnst@...fujitsu.com>,
	<linux-kernel@...r.kernel.org>, <tangchen@...fujitsu.com>
Subject: [PATCH v7 8/9] kvm, mem-hotplug: Add arch specific mmu notifier to handle apic access migration.

We are handling "L1 and L2 share one apic access page" situation when migrating
apic access page. We should do some handling when migration happens in the
following situations:

   1) when L0 is running: Update L1's vmcs in the next L0->L1 entry and L2's
      vmcs in the next L1->L2 entry.

   2) when L1 is running: Force a L1->L0 exit, update L1's vmcs in the next
      L0->L1 entry and L2's vmcs in the next L1->L2 entry.

   3) when L2 is running: Force a L2->L0 exit, update L2's vmcs in the next
      L0->L2 entry and L1's vmcs in the next L2->L1 exit.

This patch force a L1->L0 exit or L2->L0 exit when shared apic access page is
migrated using mmu notifier. Since apic access page is only used on intel x86,
this is arch specific code.

Signed-off-by: Tang Chen <tangchen@...fujitsu.com>
---
 arch/x86/kvm/x86.c       | 11 +++++++++++
 include/linux/kvm_host.h | 14 +++++++++++++-
 virt/kvm/kvm_main.c      |  3 +++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2ae2dc7..7dd4179 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6011,6 +6011,17 @@ void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_reload_apic_access_page);
 
+void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
+					   unsigned long address)
+{
+	/*
+	 * The physical address of apic access page is stored in VMCS.
+	 * Update it when it becomes invalid.
+	 */
+	if (address == gfn_to_hva(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT))
+		kvm_make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD);
+}
+
 /*
  * Returns 1 to let __vcpu_run() continue the guest execution loop without
  * exiting to the userspace.  Otherwise, the value will be returned to the
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 73de13c..b6e4d38 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -917,7 +917,19 @@ static inline int mmu_notifier_retry(struct kvm *kvm, unsigned long mmu_seq)
 		return 1;
 	return 0;
 }
-#endif
+
+#ifdef _ASM_X86_KVM_HOST_H
+void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
+					   unsigned long address);
+#else /* _ASM_X86_KVM_HOST_H */
+inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
+						  unsigned long address)
+{
+	return;
+}
+#endif /* _ASM_X86_KVM_HOST_H */
+
+#endif /* CONFIG_MMU_NOTIFIER & KVM_ARCH_WANT_MMU_NOTIFIER */
 
 #ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0f8b6f6..5427973d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -295,6 +295,9 @@ static void kvm_mmu_notifier_invalidate_page(struct mmu_notifier *mn,
 		kvm_flush_remote_tlbs(kvm);
 
 	spin_unlock(&kvm->mmu_lock);
+
+	kvm_arch_mmu_notifier_invalidate_page(kvm, address);
+
 	srcu_read_unlock(&kvm->srcu, idx);
 }
 
-- 
1.8.3.1

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