Re: [PATCH 1/1] kvm, mem-hotplug: Add arch specific mmu notifier to handle apic access migration.

Tang Chen <tangchen@xxxxxxxxxxxxxx> · Wed, 24 Sep 2014 15:31:53 +0800

On 09/24/2014 03:08 PM, Jan Kiszka wrote:
On 2014-09-24 04:09, Tang Chen wrote:
Hi Paolo,

I'm not sure if this patch is following your comment. Please review.
And all the other comments are followed. If this patch is OK, I'll
send v8 soon.

Thanks.

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.
---
  arch/arm/include/asm/kvm_host.h     |  6 ++++++
  arch/arm64/include/asm/kvm_host.h   |  6 ++++++
  arch/ia64/include/asm/kvm_host.h    |  8 ++++++++
  arch/mips/include/asm/kvm_host.h    |  7 +++++++
  arch/powerpc/include/asm/kvm_host.h |  6 ++++++
  arch/s390/include/asm/kvm_host.h    |  9 +++++++++
  arch/x86/include/asm/kvm_host.h     |  2 ++
  arch/x86/kvm/x86.c                  | 11 +++++++++++
  virt/kvm/kvm_main.c                 |  3 +++
  9 files changed, 58 insertions(+)

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 6dfb404..79bbf7d 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -182,6 +182,12 @@ static inline int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
  	return 0;
  }
  
+static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
+							 unsigned long address)
+{
+	return;
Redundant return, more cases below.

OK, will remove it. Thanks.


Jan

+}
+
  struct kvm_vcpu *kvm_arm_get_running_vcpu(void);
  struct kvm_vcpu __percpu **kvm_get_running_vcpus(void);
  
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index e10c45a..ee89fad 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -192,6 +192,12 @@ static inline int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
  	return 0;
  }
  
+static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
+							 unsigned long address)
+{
+	return;
+}
+
  struct kvm_vcpu *kvm_arm_get_running_vcpu(void);
  struct kvm_vcpu __percpu **kvm_get_running_vcpus(void);
  
diff --git a/arch/ia64/include/asm/kvm_host.h b/arch/ia64/include/asm/kvm_host.h
index db95f57..326ac55 100644
--- a/arch/ia64/include/asm/kvm_host.h
+++ b/arch/ia64/include/asm/kvm_host.h
@@ -574,6 +574,14 @@ static inline struct kvm_pt_regs *vcpu_regs(struct kvm_vcpu *v)
  	return (struct kvm_pt_regs *) ((unsigned long) v + KVM_STK_OFFSET) - 1;
  }
  
+#ifdef KVM_ARCH_WANT_MMU_NOTIFIER
+static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
+							 unsigned long address)
+{
+	return;
+}
+#endif /* KVM_ARCH_WANT_MMU_NOTIFIER */
+
  typedef int kvm_vmm_entry(void);
  typedef void kvm_tramp_entry(union context *host, union context *guest);
  
diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 7a3fc67..c392705 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -767,5 +767,12 @@ extern int kvm_mips_trans_mtc0(uint32_t inst, uint32_t *opc,
  extern void kvm_mips_dump_stats(struct kvm_vcpu *vcpu);
  extern unsigned long kvm_mips_get_ramsize(struct kvm *kvm);
  
+#ifdef KVM_ARCH_WANT_MMU_NOTIFIER
+static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
+							 unsigned long address)
+{
+	return;
+}
+#endif /* KVM_ARCH_WANT_MMU_NOTIFIER */
  
  #endif /* __MIPS_KVM_HOST_H__ */
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 98d9dd5..c16a573 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -61,6 +61,12 @@ extern int kvm_age_hva(struct kvm *kvm, unsigned long hva);
  extern int kvm_test_age_hva(struct kvm *kvm, unsigned long hva);
  extern void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);
  
+static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
+							 unsigned long address)
+{
+	return;
+}
+
  #define HPTEG_CACHE_NUM			(1 << 15)
  #define HPTEG_HASH_BITS_PTE		13
  #define HPTEG_HASH_BITS_PTE_LONG	12
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 773bef7..693290f 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -450,4 +450,13 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
  
  extern int sie64a(struct kvm_s390_sie_block *, u64 *);
  extern char sie_exit;
+
+#ifdef KVM_ARCH_WANT_MMU_NOTIFIER
+static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
+							 unsigned long address)
+{
+	return;
+}
+#endif /* KVM_ARCH_WANT_MMU_NOTIFIER */
+
  #endif
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 66480fd..408b944 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1047,6 +1047,8 @@ int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu);
  int kvm_cpu_get_interrupt(struct kvm_vcpu *v);
  void kvm_vcpu_reset(struct kvm_vcpu *vcpu);
  void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu);
+void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
+					   unsigned long address);
  
  void kvm_define_shared_msr(unsigned index, u32 msr);
  void kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c064ca6..e042ef6 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/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);
  }
  



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