[PATCH v2 4/5] kvm: Remove ept_identity_pagetable from struct kvm_arch.

[Tang Chen]

kvm_arch->ept_identity_pagetable holds the ept identity pagetable page. But
it is never used to refer to the page at all.

In vcpu initialization, it indicates two things:
1. indicates if ept page is allocated
2. indicates if a memory slot for identity page is initialized

Actually, kvm_arch->ept_identity_pagetable_done is enough to tell if the ept
identity pagetable is initialized. So we can remove ept_identity_pagetable.

Signed-off-by: Tang Chen <tangc...@cn.fujitsu.com>
---
 arch/x86/include/asm/kvm_host.h |  1 -
 arch/x86/kvm/vmx.c              | 25 +++++++++++--------------
 2 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4931415..62f973e 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -578,7 +578,6 @@ struct kvm_arch {
 
        gpa_t wall_clock;
 
-       struct page *ept_identity_pagetable;
        bool ept_identity_pagetable_done;
        gpa_t ept_identity_map_addr;
 
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 0918635e..5532ac8 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -741,6 +741,7 @@ static void vmx_sync_pir_to_irr_dummy(struct kvm_vcpu 
*vcpu);
 static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx);
 static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx);
 static bool vmx_mpx_supported(void);
+static int alloc_identity_pagetable(struct kvm *kvm);
 
 static DEFINE_PER_CPU(struct vmcs *, vmxarea);
 static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
@@ -3921,21 +3922,21 @@ out:
 
 static int init_rmode_identity_map(struct kvm *kvm)
 {
-       int i, idx, r, ret;
+       int i, idx, r, ret = 0;
        pfn_t identity_map_pfn;
        u32 tmp;
 
        if (!enable_ept)
                return 1;
-       if (unlikely(!kvm->arch.ept_identity_pagetable)) {
-               printk(KERN_ERR "EPT: identity-mapping pagetable "
-                       "haven't been allocated!\n");
-               return 0;
-       }
        if (likely(kvm->arch.ept_identity_pagetable_done))
                return 1;
-       ret = 0;
        identity_map_pfn = kvm->arch.ept_identity_map_addr >> PAGE_SHIFT;
+
+       mutex_lock(&kvm->slots_lock);
+       r = alloc_identity_pagetable(kvm);
+       if (r)
+               goto out;
+
        idx = srcu_read_lock(&kvm->srcu);
        r = kvm_clear_guest_page(kvm, identity_map_pfn, 0, PAGE_SIZE);
        if (r < 0)
@@ -3953,6 +3954,9 @@ static int init_rmode_identity_map(struct kvm *kvm)
        ret = 1;
 out:
        srcu_read_unlock(&kvm->srcu, idx);
+
+out2:
+       mutex_unlock(&kvm->slots_lock);
        return ret;
 }
 
@@ -4006,9 +4010,6 @@ static int alloc_identity_pagetable(struct kvm *kvm)
        struct kvm_userspace_memory_region kvm_userspace_mem;
        int r = 0;
 
-       mutex_lock(&kvm->slots_lock);
-       if (kvm->arch.ept_identity_pagetable)
-               goto out;
        kvm_userspace_mem.slot = IDENTITY_PAGETABLE_PRIVATE_MEMSLOT;
        kvm_userspace_mem.flags = 0;
        kvm_userspace_mem.guest_phys_addr =
@@ -4025,9 +4026,7 @@ static int alloc_identity_pagetable(struct kvm *kvm)
                goto out;
        }
 
-       kvm->arch.ept_identity_pagetable = page;
 out:
-       mutex_unlock(&kvm->slots_lock);
        return r;
 }
 
@@ -7583,8 +7582,6 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, 
unsigned int id)
                        kvm->arch.ept_identity_map_addr =
                                VMX_EPT_IDENTITY_PAGETABLE_ADDR;
                err = -ENOMEM;
-               if (alloc_identity_pagetable(kvm) != 0)
-                       goto free_vmcs;
                if (!init_rmode_identity_map(kvm))
                        goto free_vmcs;
        }
-- 
1.8.3.1

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