linux-kernel - [PATCH v12 03/84] KVM: Drop KVM_ERR_PTR_BAD_PAGE and instead return NULL to indicate an error

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Message-ID: <20240726235234.228822-4-seanjc@google.com>
Date: Fri, 26 Jul 2024 16:51:12 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>, 
	Oliver Upton <oliver.upton@...ux.dev>, Tianrui Zhao <zhaotianrui@...ngson.cn>, 
	Bibo Mao <maobibo@...ngson.cn>, Huacai Chen <chenhuacai@...nel.org>, 
	Michael Ellerman <mpe@...erman.id.au>, Anup Patel <anup@...infault.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Christian Borntraeger <borntraeger@...ux.ibm.com>, 
	Janosch Frank <frankja@...ux.ibm.com>, Claudio Imbrenda <imbrenda@...ux.ibm.com>, 
	Sean Christopherson <seanjc@...gle.com>
Cc: kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, loongarch@...ts.linux.dev, linux-mips@...r.kernel.org, 
	linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	David Matlack <dmatlack@...gle.com>, David Stevens <stevensd@...omium.org>
Subject: [PATCH v12 03/84] KVM: Drop KVM_ERR_PTR_BAD_PAGE and instead return
 NULL to indicate an error

Remove KVM_ERR_PTR_BAD_PAGE and instead return NULL, as "bad page" is just
a leftover bit of weirdness from days of old when KVM stuffed a "bad" page
into the guest instead of actually handling missing pages.  See commit
cea7bb21280e ("KVM: MMU: Make gfn_to_page() always safe").

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/powerpc/kvm/book3s_pr.c          |  2 +-
 arch/powerpc/kvm/book3s_xive_native.c |  2 +-
 arch/s390/kvm/vsie.c                  |  2 +-
 arch/x86/kvm/lapic.c                  |  2 +-
 include/linux/kvm_host.h              |  7 -------
 virt/kvm/kvm_main.c                   | 15 ++++++---------
 6 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index a7d7137ea0c8..1bdcd4ee4813 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -645,7 +645,7 @@ static void kvmppc_patch_dcbz(struct kvm_vcpu *vcpu, struct kvmppc_pte *pte)
 	int i;
 
 	hpage = gfn_to_page(vcpu->kvm, pte->raddr >> PAGE_SHIFT);
-	if (is_error_page(hpage))
+	if (!hpage)
 		return;
 
 	hpage_offset = pte->raddr & ~PAGE_MASK;
diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
index 6e2ebbd8aaac..d9bf1bc3ff61 100644
--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -654,7 +654,7 @@ static int kvmppc_xive_native_set_queue_config(struct kvmppc_xive *xive,
 	}
 
 	page = gfn_to_page(kvm, gfn);
-	if (is_error_page(page)) {
+	if (!page) {
 		srcu_read_unlock(&kvm->srcu, srcu_idx);
 		pr_err("Couldn't get queue page %llx!\n", kvm_eq.qaddr);
 		return -EINVAL;
diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 54deafd0d698..566697ee37eb 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -661,7 +661,7 @@ static int pin_guest_page(struct kvm *kvm, gpa_t gpa, hpa_t *hpa)
 	struct page *page;
 
 	page = gfn_to_page(kvm, gpa_to_gfn(gpa));
-	if (is_error_page(page))
+	if (!page)
 		return -EINVAL;
 	*hpa = (hpa_t)page_to_phys(page) + (gpa & ~PAGE_MASK);
 	return 0;
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index a7172ba59ad2..6d65b36fac29 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2629,7 +2629,7 @@ int kvm_alloc_apic_access_page(struct kvm *kvm)
 	}
 
 	page = gfn_to_page(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT);
-	if (is_error_page(page)) {
+	if (!page) {
 		ret = -EFAULT;
 		goto out;
 	}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 689e8be873a7..3d9617d1de41 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -153,13 +153,6 @@ static inline bool kvm_is_error_gpa(gpa_t gpa)
 	return gpa == INVALID_GPA;
 }
 
-#define KVM_ERR_PTR_BAD_PAGE	(ERR_PTR(-ENOENT))
-
-static inline bool is_error_page(struct page *page)
-{
-	return IS_ERR(page);
-}
-
 #define KVM_REQUEST_MASK           GENMASK(7,0)
 #define KVM_REQUEST_NO_WAKEUP      BIT(8)
 #define KVM_REQUEST_WAIT           BIT(9)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d0788d0a72cc..fd8c212b8de7 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3085,19 +3085,14 @@ EXPORT_SYMBOL_GPL(gfn_to_page_many_atomic);
  */
 struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
 {
-	struct page *page;
 	kvm_pfn_t pfn;
 
 	pfn = gfn_to_pfn(kvm, gfn);
 
 	if (is_error_noslot_pfn(pfn))
-		return KVM_ERR_PTR_BAD_PAGE;
+		return NULL;
 
-	page = kvm_pfn_to_refcounted_page(pfn);
-	if (!page)
-		return KVM_ERR_PTR_BAD_PAGE;
-
-	return page;
+	return kvm_pfn_to_refcounted_page(pfn);
 }
 EXPORT_SYMBOL_GPL(gfn_to_page);
 
@@ -3191,7 +3186,8 @@ static void kvm_set_page_accessed(struct page *page)
 
 void kvm_release_page_clean(struct page *page)
 {
-	WARN_ON(is_error_page(page));
+	if (WARN_ON(!page))
+		return;
 
 	kvm_set_page_accessed(page);
 	put_page(page);
@@ -3215,7 +3211,8 @@ EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);
 
 void kvm_release_page_dirty(struct page *page)
 {
-	WARN_ON(is_error_page(page));
+	if (WARN_ON(!page))
+		return;
 
 	kvm_set_page_dirty(page);
 	kvm_release_page_clean(page);
-- 
2.46.0.rc1.232.g9752f9e123-goog