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Subject[PATCH] KVM: arm/arm64: replacing per-VM's per-CPU variable
Date
Using a global per-CPU variable instead of per-VM's per-CPU variable.

Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
---
arch/arm/include/asm/kvm_host.h | 3 ---
arch/arm64/include/asm/kvm_host.h | 3 ---
virt/kvm/arm/arm.c | 26 ++++++--------------------
3 files changed, 6 insertions(+), 26 deletions(-)

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 248b930..4224f3b 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -59,9 +59,6 @@ struct kvm_arch {
/* VTTBR value associated with below pgd and vmid */
u64 vttbr;

- /* The last vcpu id that ran on each physical CPU */
- int __percpu *last_vcpu_ran;
-
/*
* Anything that is not used directly from assembly code goes
* here.
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 596f8e4..5035a08 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -67,9 +67,6 @@ struct kvm_arch {
/* VTTBR value associated with above pgd and vmid */
u64 vttbr;

- /* The last vcpu id that ran on each physical CPU */
- int __percpu *last_vcpu_ran;
-
/* The maximum number of vCPUs depends on the used GIC model */
int max_vcpus;

diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 86941f6..a67ffb0 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -59,6 +59,8 @@
/* Per-CPU variable containing the currently running vcpu. */
static DEFINE_PER_CPU(struct kvm_vcpu *, kvm_arm_running_vcpu);

+static DEFINE_PER_CPU(struct kvm_vcpu *, kvm_last_ran_vcpu);
+
/* The VMID used in the VTTBR */
static atomic64_t kvm_vmid_gen = ATOMIC64_INIT(1);
static u32 kvm_next_vmid;
@@ -115,18 +117,11 @@ void kvm_arch_check_processor_compat(void *rtn)
*/
int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
{
- int ret, cpu;
+ int ret;

if (type)
return -EINVAL;

- kvm->arch.last_vcpu_ran = alloc_percpu(typeof(*kvm->arch.last_vcpu_ran));
- if (!kvm->arch.last_vcpu_ran)
- return -ENOMEM;
-
- for_each_possible_cpu(cpu)
- *per_cpu_ptr(kvm->arch.last_vcpu_ran, cpu) = -1;
-
ret = kvm_alloc_stage2_pgd(kvm);
if (ret)
goto out_fail_alloc;
@@ -147,9 +142,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
return ret;
out_free_stage2_pgd:
kvm_free_stage2_pgd(kvm);
-out_fail_alloc:
- free_percpu(kvm->arch.last_vcpu_ran);
- kvm->arch.last_vcpu_ran = NULL;
+out_fail_alloc:
return ret;
}

@@ -179,9 +172,6 @@ void kvm_arch_destroy_vm(struct kvm *kvm)

kvm_vgic_destroy(kvm);

- free_percpu(kvm->arch.last_vcpu_ran);
- kvm->arch.last_vcpu_ran = NULL;
-
for (i = 0; i < KVM_MAX_VCPUS; ++i) {
if (kvm->vcpus[i]) {
kvm_arch_vcpu_free(kvm->vcpus[i]);
@@ -343,17 +333,13 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)

void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
- int *last_ran;
-
- last_ran = this_cpu_ptr(vcpu->kvm->arch.last_vcpu_ran);
-
/*
* We might get preempted before the vCPU actually runs, but
* over-invalidation doesn't affect correctness.
*/
- if (*last_ran != vcpu->vcpu_id) {
+ if (per_cpu(kvm_last_ran_vcpu, cpu) != vcpu) {
kvm_call_hyp(__kvm_tlb_flush_local_vmid, vcpu);
- *last_ran = vcpu->vcpu_id;
+ per_cpu(kvm_last_ran_vcpu, cpu) = vcpu;
}

vcpu->cpu = cpu;
--
1.8.3.1
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