[PATCH v4 5/6] kvm, mem-hotplug: Reload L1's apic access page on migration when L2 is running.
From: Tang Chen
Date: Wed Aug 27 2014 - 06:17:29 EST
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@xxxxxxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/svm.c | 6 ++++++
arch/x86/kvm/vmx.c | 32 ++++++++++++++++++++++++++++++++
arch/x86/kvm/x86.c | 3 +++
virt/kvm/kvm_main.c | 1 +
5 files changed, 43 insertions(+)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 514183e..13fbb62 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -740,6 +740,7 @@ struct kvm_x86_ops {
void (*load_eoi_exitmap)(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap);
void (*set_virtual_x2apic_mode)(struct kvm_vcpu *vcpu, bool set);
void (*set_apic_access_page_addr)(struct kvm *kvm, hpa_t hpa);
+ void (*set_nested_apic_page_migrated)(struct kvm_vcpu *vcpu, bool set);
void (*deliver_posted_interrupt)(struct kvm_vcpu *vcpu, int vector);
void (*sync_pir_to_irr)(struct kvm_vcpu *vcpu);
int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index f2eacc4..da88646 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3624,6 +3624,11 @@ static void svm_set_apic_access_page_addr(struct kvm *kvm, hpa_t hpa)
return;
}
+static void svm_set_nested_apic_page_migrated(struct kvm_vcpu *vcpu, bool set)
+{
+ return;
+}
+
static int svm_vm_has_apicv(struct kvm *kvm)
{
return 0;
@@ -4379,6 +4384,7 @@ static struct kvm_x86_ops svm_x86_ops = {
.update_cr8_intercept = update_cr8_intercept,
.set_virtual_x2apic_mode = svm_set_virtual_x2apic_mode,
.set_apic_access_page_addr = svm_set_apic_access_page_addr,
+ .set_nested_apic_page_migrated = svm_set_nested_apic_page_migrated,
.vm_has_apicv = svm_vm_has_apicv,
.load_eoi_exitmap = svm_load_eoi_exitmap,
.hwapic_isr_update = svm_hwapic_isr_update,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index da6d55d..9035fd1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -379,6 +379,16 @@ struct nested_vmx {
* we must keep them pinned while L2 runs.
*/
struct page *apic_access_page;
+ /*
+ * L1's apic access page can be migrated. When L1 and L2 are sharing
+ * the apic access page, after the page is migrated when L2 is running,
+ * we have to reload it to L1 vmcs before we enter L1.
+ *
+ * When the shared apic access page is migrated in L1 mode, we don't
+ * need to do anything else because we reload apic access page each
+ * time when entering L2 in prepare_vmcs02().
+ */
+ bool apic_access_page_migrated;
u64 msr_ia32_feature_control;
struct hrtimer preemption_timer;
@@ -7098,6 +7108,12 @@ static void vmx_set_apic_access_page_addr(struct kvm *kvm, hpa_t hpa)
vmcs_write64(APIC_ACCESS_ADDR, hpa);
}
+static void vmx_set_nested_apic_page_migrated(struct kvm_vcpu *vcpu, bool set)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ vmx->nested.apic_access_page_migrated = set;
+}
+
static void vmx_hwapic_isr_update(struct kvm *kvm, int isr)
{
u16 status;
@@ -8796,6 +8812,21 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
}
/*
+ * When shared (L1 & L2) apic access page is migrated during L2 is
+ * running, mmu_notifier will force to reload the page's hpa for L2
+ * vmcs. Need to reload it for L1 before entering L1.
+ */
+ if (vmx->nested.apic_access_page_migrated) {
+ /*
+ * Do not call kvm_reload_apic_access_page() because we are now
+ * in L2. We should not call make_all_cpus_request() to exit to
+ * L0, otherwise we will reload for L2 vmcs again.
+ */
+ kvm_reload_apic_access_page(vcpu->kvm);
+ vmx->nested.apic_access_page_migrated = false;
+ }
+
+ /*
* 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.
@@ -8916,6 +8947,7 @@ static struct kvm_x86_ops vmx_x86_ops = {
.update_cr8_intercept = update_cr8_intercept,
.set_virtual_x2apic_mode = vmx_set_virtual_x2apic_mode,
.set_apic_access_page_addr = vmx_set_apic_access_page_addr,
+ .set_nested_apic_page_migrated = vmx_set_nested_apic_page_migrated,
.vm_has_apicv = vmx_vm_has_apicv,
.load_eoi_exitmap = vmx_load_eoi_exitmap,
.hwapic_irr_update = vmx_hwapic_irr_update,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 96f4188..131b6e8 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6000,6 +6000,9 @@ static void vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT);
kvm_x86_ops->set_apic_access_page_addr(vcpu->kvm,
page_to_phys(vcpu->kvm->arch.apic_access_page));
+
+ if (is_guest_mode(vcpu))
+ kvm_x86_ops->set_nested_apic_page_migrated(vcpu, true);
}
/*
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d8280de..784127e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -214,6 +214,7 @@ void kvm_reload_apic_access_page(struct kvm *kvm)
{
make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD);
}
+EXPORT_SYMBOL_GPL(kvm_reload_apic_access_page);
int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
{
--
1.8.3.1
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