[PATCH v2 3/6] KVM: MMU: make return value of mmio page fault handler more readable

Xiao Guangrong
2013-04-01T09:57:08Z

Define some meaningful names instead of raw code

Signed-off-by: Xiao Guangrong <xiaoguangrong@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 be4f733..31c5586 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3182,17 +3182,12 @@ 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_EMU;

spte = walk_shadow_page_get_mmio_spte(vcpu, addr);

@@ -3205,7 +3200,7 @@ 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_EMU;
}

/*
@@ -3213,13 +3208,13 @@ 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);

@@ -3229,7 +3224,7 @@ 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 2adcbc2..6b4ba1e 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_EMU: 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_EMU = 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 915ef56..d0f2790 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5135,10 +5135,10 @@ 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_EMU))
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 */
--
1.7.7.6