linux-kernel - [PATCH v7 3/9] kvm: Make init_rmode_identity

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Date:	Sat, 20 Sep 2014 18:47:45 +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 v7 3/9] kvm: Make init_rmode_identity_map() return 0 on success.

In init_rmode_identity_map(), there two variables indicating the return
value, r and ret, and it return 0 on error, 1 on success. The function
is only called by vmx_create_vcpu(), and r is redundant.

This patch removes the redundant variable r, and make init_rmode_identity_map()
return 0 on success, -errno on failure.

Signed-off-by: Tang Chen <tangchen@...fujitsu.com>
---
 arch/x86/kvm/vmx.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 4fb84ad..72a0470 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3939,45 +3939,42 @@ out:
 
 static int init_rmode_identity_map(struct kvm *kvm)
 {
-	int i, idx, r, ret = 0;
+	int i, idx, ret = 0;
 	pfn_t identity_map_pfn;
 	u32 tmp;
 
 	if (!enable_ept)
-		return 1;
+		return 0;
 
 	/* Protect kvm->arch.ept_identity_pagetable_done. */
 	mutex_lock(&kvm->slots_lock);
 
-	if (likely(kvm->arch.ept_identity_pagetable_done)) {
-		ret = 1;
+	if (likely(kvm->arch.ept_identity_pagetable_done))
 		goto out2;
-	}
 
 	identity_map_pfn = kvm->arch.ept_identity_map_addr >> PAGE_SHIFT;
 
-	r = alloc_identity_pagetable(kvm);
-	if (r)
+	ret = alloc_identity_pagetable(kvm);
+	if (ret)
 		goto out2;
 
 	idx = srcu_read_lock(&kvm->srcu);
-	r = kvm_clear_guest_page(kvm, identity_map_pfn, 0, PAGE_SIZE);
-	if (r < 0)
+	ret = kvm_clear_guest_page(kvm, identity_map_pfn, 0, PAGE_SIZE);
+	if (ret)
 		goto out;
 	/* Set up identity-mapping pagetable for EPT in real mode */
 	for (i = 0; i < PT32_ENT_PER_PAGE; i++) {
 		tmp = (i << 22) + (_PAGE_PRESENT | _PAGE_RW | _PAGE_USER |
 			_PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_PSE);
-		r = kvm_write_guest_page(kvm, identity_map_pfn,
+		ret = kvm_write_guest_page(kvm, identity_map_pfn,
 				&tmp, i * sizeof(tmp), sizeof(tmp));
-		if (r < 0)
+		if (ret)
 			goto out;
 	}
 	kvm->arch.ept_identity_pagetable_done = true;
-	ret = 1;
+
 out:
 	srcu_read_unlock(&kvm->srcu, idx);
-
 out2:
 	mutex_unlock(&kvm->slots_lock);
 	return ret;
@@ -7604,11 +7601,13 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
 	if (err)
 		goto free_vcpu;
 
+	/* Set err to -ENOMEM to handle memory allocation error. */
+	err = -ENOMEM;
+
 	vmx->guest_msrs = kmalloc(PAGE_SIZE, GFP_KERNEL);
 	BUILD_BUG_ON(ARRAY_SIZE(vmx_msr_index) * sizeof(vmx->guest_msrs[0])
 		     > PAGE_SIZE);
 
-	err = -ENOMEM;
 	if (!vmx->guest_msrs) {
 		goto uninit_vcpu;
 	}
@@ -7641,8 +7640,8 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
 		if (!kvm->arch.ept_identity_map_addr)
 			kvm->arch.ept_identity_map_addr =
 				VMX_EPT_IDENTITY_PAGETABLE_ADDR;
-		err = -ENOMEM;
-		if (!init_rmode_identity_map(kvm))
+		err = init_rmode_identity_map(kvm);
+		if (err < 0)
 			goto free_vmcs;
 	}
 
-- 
1.8.3.1

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