Date:   Tue, 10 Oct 2017 11:10:59 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: [PATCH] KVM: x86: extend usage of RET_MMIO_PF_* constants

The x86 MMU if full of code that returns 0 and 1 for retry/emulate.  Use
the existing RET_MMIO_PF_RETRY/RET_MMIO_PF_EMULATE enum, renaming it to
drop the MMIO part.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/mmu.c         | 95 ++++++++++++++++++++++------------------------
 arch/x86/kvm/paging_tmpl.h | 18 ++++-----
 2 files changed, 55 insertions(+), 58 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 1706683d5fd7..c65593d7f23d 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -150,6 +150,20 @@ enum {
 /* make pte_list_desc fit well in cache line */
 #define PTE_LIST_EXT 3
 
+/*
+ * Return values of handle_mmio_page_fault and mmu.page_fault:
+ * RET_PF_RETRY: let CPU fault again on the address.
+ * RET_PF_EMULATE: mmio page fault, emulate the instruction directly.
+ *
+ * For handle_mmio_page_fault only:
+ * RET_PF_INVALID: the spte is invalid, let the real page fault path update it.
+ */
+enum {
+	RET_PF_RETRY = 0,
+	RET_PF_EMULATE = 1,
+	RET_PF_INVALID = 2,
+};
+
 struct pte_list_desc {
 	u64 *sptes[PTE_LIST_EXT];
 	struct pte_list_desc *more;
@@ -2794,13 +2808,13 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 	return ret;
 }
 
-static bool mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
-			 int write_fault, int level, gfn_t gfn, kvm_pfn_t pfn,
-			 bool speculative, bool host_writable)
+static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
+			int write_fault, int level, gfn_t gfn, kvm_pfn_t pfn,
+		       	bool speculative, bool host_writable)
 {
 	int was_rmapped = 0;
 	int rmap_count;
-	bool emulate = false;
+	int ret = RET_PF_RETRY;
 
 	pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__,
 		 *sptep, write_fault, gfn);
@@ -2830,12 +2844,12 @@ static bool mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
 	if (set_spte(vcpu, sptep, pte_access, level, gfn, pfn, speculative,
 	      true, host_writable)) {
 		if (write_fault)
-			emulate = true;
+			ret = RET_PF_EMULATE;
 		kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
 	}
 
 	if (unlikely(is_mmio_spte(*sptep)))
-		emulate = true;
+		ret = RET_PF_EMULATE;
 
 	pgprintk("%s: setting spte %llx\n", __func__, *sptep);
 	pgprintk("instantiating %s PTE (%s) at %llx (%llx) addr %p\n",
@@ -2855,7 +2869,7 @@ static bool mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
 
 	kvm_release_pfn_clean(pfn);
 
-	return emulate;
+	return ret;
 }
 
 static kvm_pfn_t pte_prefetch_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn,
@@ -2994,14 +3008,13 @@ static int kvm_handle_bad_page(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn)
 	 * Do not cache the mmio info caused by writing the readonly gfn
 	 * into the spte otherwise read access on readonly gfn also can
 	 * caused mmio page fault and treat it as mmio access.
-	 * Return 1 to tell kvm to emulate it.
 	 */
 	if (pfn == KVM_PFN_ERR_RO_FAULT)
-		return 1;
+		return RET_PF_EMULATE;
 
 	if (pfn == KVM_PFN_ERR_HWPOISON) {
 		kvm_send_hwpoison_signal(kvm_vcpu_gfn_to_hva(vcpu, gfn), current);
-		return 0;
+		return RET_PF_RETRY;
 	}
 
 	return -EFAULT;
@@ -3286,13 +3299,13 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, u32 error_code,
 	}
 
 	if (fast_page_fault(vcpu, v, level, error_code))
-		return 0;
+		return RET_PF_RETRY;
 
 	mmu_seq = vcpu->kvm->mmu_notifier_seq;
 	smp_rmb();
 
 	if (try_async_pf(vcpu, prefault, gfn, v, &pfn, write, &map_writable))
-		return 0;
+		return RET_PF_RETRY;
 
 	if (handle_abnormal_pfn(vcpu, v, gfn, pfn, ACC_ALL, &r))
 		return r;
@@ -3312,7 +3325,7 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, u32 error_code,
 out_unlock:
 	spin_unlock(&vcpu->kvm->mmu_lock);
 	kvm_release_pfn_clean(pfn);
-	return 0;
+	return RET_PF_RETRY;
 }
 
 
@@ -3659,54 +3672,38 @@ static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct)
 	return reserved;
 }
 
-/*
- * Return values of handle_mmio_page_fault:
- * RET_MMIO_PF_EMULATE: it is a real mmio page fault, emulate the instruction
- *			directly.
- * RET_MMIO_PF_INVALID: invalid spte is detected then let the real page
- *			fault path update the mmio spte.
- * RET_MMIO_PF_RETRY: let CPU fault again on the address.
- * RET_MMIO_PF_BUG: a bug was detected (and a WARN was printed).
- */
-enum {
-	RET_MMIO_PF_EMULATE = 1,
-	RET_MMIO_PF_INVALID = 2,
-	RET_MMIO_PF_RETRY = 0,
-	RET_MMIO_PF_BUG = -1
-};
-
 static int handle_mmio_page_fault(struct kvm_vcpu *vcpu, u64 addr, bool direct)
 {
 	u64 spte;
 	bool reserved;
 
 	if (mmio_info_in_cache(vcpu, addr, direct))
-		return RET_MMIO_PF_EMULATE;
+		return RET_PF_EMULATE;
 
 	reserved = walk_shadow_page_get_mmio_spte(vcpu, addr, &spte);
 	if (WARN_ON(reserved))
-		return RET_MMIO_PF_BUG;
+		return -EINVAL;
 
 	if (is_mmio_spte(spte)) {
 		gfn_t gfn = get_mmio_spte_gfn(spte);
 		unsigned access = get_mmio_spte_access(spte);
 
 		if (!check_mmio_spte(vcpu, spte))
-			return RET_MMIO_PF_INVALID;
+			return RET_PF_INVALID;
 
 		if (direct)
 			addr = 0;
 
 		trace_handle_mmio_page_fault(addr, gfn, access);
 		vcpu_cache_mmio_info(vcpu, addr, gfn, access);
-		return RET_MMIO_PF_EMULATE;
+		return RET_PF_EMULATE;
 	}
 
 	/*
 	 * If the page table is zapped by other cpus, let CPU fault again on
 	 * the address.
 	 */
-	return RET_MMIO_PF_RETRY;
+	return RET_PF_RETRY;
 }
 EXPORT_SYMBOL_GPL(handle_mmio_page_fault);
 
@@ -3756,7 +3753,7 @@ static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
 	pgprintk("%s: gva %lx error %x\n", __func__, gva, error_code);
 
 	if (page_fault_handle_page_track(vcpu, error_code, gfn))
-		return 1;
+		return RET_PF_EMULATE;
 
 	r = mmu_topup_memory_caches(vcpu);
 	if (r)
@@ -3875,7 +3872,7 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
 	MMU_WARN_ON(!VALID_PAGE(vcpu->arch.mmu.root_hpa));
 
 	if (page_fault_handle_page_track(vcpu, error_code, gfn))
-		return 1;
+		return RET_PF_EMULATE;
 
 	r = mmu_topup_memory_caches(vcpu);
 	if (r)
@@ -3892,13 +3889,13 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
 	}
 
 	if (fast_page_fault(vcpu, gpa, level, error_code))
-		return 0;
+		return RET_PF_RETRY;
 
 	mmu_seq = vcpu->kvm->mmu_notifier_seq;
 	smp_rmb();
 
 	if (try_async_pf(vcpu, prefault, gfn, gpa, &pfn, write, &map_writable))
-		return 0;
+		return RET_PF_RETRY;
 
 	if (handle_abnormal_pfn(vcpu, 0, gfn, pfn, ACC_ALL, &r))
 		return r;
@@ -3918,7 +3915,7 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
 out_unlock:
 	spin_unlock(&vcpu->kvm->mmu_lock);
 	kvm_release_pfn_clean(pfn);
-	return 0;
+	return RET_PF_RETRY;
 }
 
 static void nonpaging_init_context(struct kvm_vcpu *vcpu,
@@ -4916,25 +4913,25 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u64 error_code,
 		vcpu->arch.gpa_val = cr2;
 	}
 
+	r = RET_PF_INVALID;
 	if (unlikely(error_code & PFERR_RSVD_MASK)) {
 		r = handle_mmio_page_fault(vcpu, cr2, direct);
-		if (r == RET_MMIO_PF_EMULATE) {
+		if (r == RET_PF_EMULATE) {
 			emulation_type = 0;
 			goto emulate;
 		}
-		if (r == RET_MMIO_PF_RETRY)
-			return 1;
-		if (r < 0)
-			return r;
-		/* Must be RET_MMIO_PF_INVALID.  */
 	}
 
-	r = vcpu->arch.mmu.page_fault(vcpu, cr2, lower_32_bits(error_code),
-				      false);
+	if (r == RET_PF_INVALID) {
+		r = vcpu->arch.mmu.page_fault(vcpu, cr2, lower_32_bits(error_code),
+					      false);
+		WARN_ON(r == RET_PF_INVALID);
+	}
+
+	if (r == RET_PF_RETRY)
+		return 1;
 	if (r < 0)
 		return r;
-	if (!r)
-		return 1;
 
 	/*
 	 * Before emulating the instruction, check if the error code
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 86b68dc5a649..7d6be951443e 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -592,7 +592,7 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
 	struct kvm_mmu_page *sp = NULL;
 	struct kvm_shadow_walk_iterator it;
 	unsigned direct_access, access = gw->pt_access;
-	int top_level, emulate;
+	int top_level, ret;
 
 	direct_access = gw->pte_access;
 
@@ -658,15 +658,15 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
 	}
 
 	clear_sp_write_flooding_count(it.sptep);
-	emulate = mmu_set_spte(vcpu, it.sptep, gw->pte_access, write_fault,
-			       it.level, gw->gfn, pfn, prefault, map_writable);
+	ret = mmu_set_spte(vcpu, it.sptep, gw->pte_access, write_fault,
+			   it.level, gw->gfn, pfn, prefault, map_writable);
 	FNAME(pte_prefetch)(vcpu, gw, it.sptep);
 
-	return emulate;
+	return ret;
 
 out_gpte_changed:
 	kvm_release_pfn_clean(pfn);
-	return 0;
+	return RET_PF_RETRY;
 }
 
  /*
@@ -761,12 +761,12 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
 		if (!prefault)
 			inject_page_fault(vcpu, &walker.fault);
 
-		return 0;
+		return RET_PF_RETRY;
 	}
 
 	if (page_fault_handle_page_track(vcpu, error_code, walker.gfn)) {
 		shadow_page_table_clear_flood(vcpu, addr);
-		return 1;
+		return RET_PF_EMULATE;
 	}
 
 	vcpu->arch.write_fault_to_shadow_pgtable = false;
@@ -788,7 +788,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
 
 	if (try_async_pf(vcpu, prefault, walker.gfn, addr, &pfn, write_fault,
 			 &map_writable))
-		return 0;
+		return RET_PF_RETRY;
 
 	if (handle_abnormal_pfn(vcpu, addr, walker.gfn, pfn, walker.pte_access, &r))
 		return r;
@@ -833,7 +833,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
 out_unlock:
 	spin_unlock(&vcpu->kvm->mmu_lock);
 	kvm_release_pfn_clean(pfn);
-	return 0;
+	return RET_PF_EMULATE;
 }
 
 static gpa_t FNAME(get_level1_sp_gpa)(struct kvm_mmu_page *sp)
-- 
1.8.3.1

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