linux-kernel - [PATCH v6 5/6] kvm, mem-hotplug: Reload L1's apic access page on migration when L2 is running.

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Date:	Tue, 16 Sep 2014 18:42:01 +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 v6 5/6] kvm, mem-hotplug: Reload L1's apic access page on migration when L2 is running.

This patch only handle "L1 and L2 vm share one apic access page" situation.

When L1 vm is running, if the shared apic access page is migrated, mmu_notifier will
request all vcpus to exit to L0, and reload apic access page physical address for
all the vcpus' vmcs (which is done by patch 5/6). And when it enters L2 vm, L2's vmcs
will be updated in prepare_vmcs02() called by nested_vm_run(). So we need to do
nothing.

When L2 vm is running, if the shared apic access page is migrated, mmu_notifier will
request all vcpus to exit to L0, and reload apic access page physical address for
all L2 vmcs. And this patch requests apic access page reload in L2->L1 vmexit.

Signed-off-by: Tang Chen <tangchen@...fujitsu.com>
---
 arch/x86/include/asm/kvm_host.h | 1 +
 arch/x86/kvm/vmx.c              | 6 ++++++
 arch/x86/kvm/x86.c              | 3 ++-
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 514183e..92b3e72 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1046,6 +1046,7 @@ int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu);
 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_define_shared_msr(unsigned index, u32 msr);
 void kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index a1a9797..d0d5981 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8795,6 +8795,12 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 	}
 
 	/*
+	 * We are now running in L2, mmu_notifier will force to reload the
+	 * page's hpa for L2 vmcs. Need to reload it for L1 before entering L1.
+	 */
+	kvm_vcpu_reload_apic_access_page(vcpu);
+
+	/*
 	 * Exiting from L2 to L1, we're now back to L1 which thinks it just
 	 * finished a VMLAUNCH or VMRESUME instruction, so we need to set the
 	 * success or failure flag accordingly.
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 27c3d30..3f458b2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5989,7 +5989,7 @@ static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)
 	kvm_apic_update_tmr(vcpu, tmr);
 }
 
-static void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
+void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
 {
 	/*
 	 * apic access page could be migrated. When the page is being migrated,
@@ -6001,6 +6001,7 @@ static void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
 	kvm_x86_ops->set_apic_access_page_addr(vcpu->kvm,
 				page_to_phys(vcpu->kvm->arch.apic_access_page));
 }
+EXPORT_SYMBOL_GPL(kvm_vcpu_reload_apic_access_page);
 
 /*
  * Returns 1 to let __vcpu_run() continue the guest execution loop without
-- 
1.8.3.1

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