[PATCH v3 3/6] KVM: MMU: make return value of mmio page fault handler more readable

[Xiao Guangrong]

Define some meaningful names instead of raw code

Signed-off-by: Xiao Guangrong <xiaoguangr...@linux.vnet.ibm.com>
---
 arch/x86/kvm/mmu.c | 15 +++++----------
 arch/x86/kvm/mmu.h | 14 ++++++++++++++
 arch/x86/kvm/vmx.c |  4 ++--
 3 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index eca91bd..044d8c0 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3222,17 +3222,12 @@ static u64 walk_shadow_page_get_mmio_spte(struct 
kvm_vcpu *vcpu, u64 addr)
        return spte;
 }
 
-/*
- * If it is a real mmio page fault, return 1 and emulat the instruction
- * directly, return 0 to let CPU fault again on the address, -1 is
- * returned if bug is detected.
- */
 int handle_mmio_page_fault_common(struct kvm_vcpu *vcpu, u64 addr, bool direct)
 {
        u64 spte;
 
        if (quickly_check_mmio_pf(vcpu, addr, direct))
-               return 1;
+               return RET_MMIO_PF_EMULATE;
 
        spte = walk_shadow_page_get_mmio_spte(vcpu, addr);
 
@@ -3245,7 +3240,7 @@ int handle_mmio_page_fault_common(struct kvm_vcpu *vcpu, 
u64 addr, bool direct)
 
                trace_handle_mmio_page_fault(addr, gfn, access);
                vcpu_cache_mmio_info(vcpu, addr, gfn, access);
-               return 1;
+               return RET_MMIO_PF_EMULATE;
        }
 
        /*
@@ -3253,13 +3248,13 @@ int handle_mmio_page_fault_common(struct kvm_vcpu 
*vcpu, u64 addr, bool direct)
         * it's a BUG if the gfn is not a mmio page.
         */
        if (direct && !check_direct_spte_mmio_pf(spte))
-               return -1;
+               return RET_MMIO_PF_BUG;
 
        /*
         * If the page table is zapped by other cpus, let CPU fault again on
         * the address.
         */
-       return 0;
+       return RET_MMIO_PF_RETRY;
 }
 EXPORT_SYMBOL_GPL(handle_mmio_page_fault_common);
 
@@ -3269,7 +3264,7 @@ static int handle_mmio_page_fault(struct kvm_vcpu *vcpu, 
u64 addr,
        int ret;
 
        ret = handle_mmio_page_fault_common(vcpu, addr, direct);
-       WARN_ON(ret < 0);
+       WARN_ON(ret == RET_MMIO_PF_BUG);
        return ret;
 }
 
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 922bfae..ba6a19c 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -52,6 +52,20 @@
 
 int kvm_mmu_get_spte_hierarchy(struct kvm_vcpu *vcpu, u64 addr, u64 sptes[4]);
 void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask);
+
+/*
+ * Return values of handle_mmio_page_fault_common:
+ * RET_MMIO_PF_EMULATE: it is a real mmio page fault, emulate the instruction
+ *                      directly.
+ * RET_MMIO_PF_RETRY: let CPU fault again on the address.
+ * RET_MMIO_PF_BUG: bug is detected.
+ */
+enum {
+       RET_MMIO_PF_EMULATE = 1,
+       RET_MMIO_PF_RETRY = 0,
+       RET_MMIO_PF_BUG = -1
+};
+
 int handle_mmio_page_fault_common(struct kvm_vcpu *vcpu, u64 addr, bool 
direct);
 int kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context);
 
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 78ee123..85c8d51 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5366,10 +5366,10 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu)
        gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
 
        ret = handle_mmio_page_fault_common(vcpu, gpa, true);
-       if (likely(ret == 1))
+       if (likely(ret == RET_MMIO_PF_EMULATE))
                return x86_emulate_instruction(vcpu, gpa, 0, NULL, 0) ==
                                              EMULATE_DONE;
-       if (unlikely(!ret))
+       if (unlikely(ret == RET_MMIO_PF_RETRY))
                return 1;
 
        /* It is the real ept misconfig */
-- 
1.8.1.4

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