linux-kernel - [PATCH v12 19/84] KVM: Explicitly initialize all fields at the start of kvm_vcpu

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Message-ID: <20240726235234.228822-20-seanjc@google.com>
Date: Fri, 26 Jul 2024 16:51:28 -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 19/84] KVM: Explicitly initialize all fields at the start
 of kvm_vcpu_map()

Explicitly initialize the entire kvm_host_map structure when mapping a
pfn, as some callers declare their struct on the stack, i.e. don't
zero-initialize the struct, which makes the map->hva in kvm_vcpu_unmap()
*very* suspect.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 virt/kvm/kvm_main.c | 40 ++++++++++++++++------------------------
 1 file changed, 16 insertions(+), 24 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 21ff0f4fa02c..67a50b87bb87 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3088,32 +3088,24 @@ void kvm_release_pfn(kvm_pfn_t pfn, bool dirty)
 
 int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
 {
-	kvm_pfn_t pfn;
-	void *hva = NULL;
-	struct page *page = KVM_UNMAPPED_PAGE;
-
-	pfn = gfn_to_pfn(vcpu->kvm, gfn);
-	if (is_error_noslot_pfn(pfn))
-		return -EINVAL;
-
-	if (pfn_valid(pfn)) {
-		page = pfn_to_page(pfn);
-		hva = kmap(page);
-#ifdef CONFIG_HAS_IOMEM
-	} else {
-		hva = memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB);
-#endif
-	}
-
-	if (!hva)
-		return -EFAULT;
-
-	map->page = page;
-	map->hva = hva;
-	map->pfn = pfn;
+	map->page = KVM_UNMAPPED_PAGE;
+	map->hva = NULL;
 	map->gfn = gfn;
 
-	return 0;
+	map->pfn = gfn_to_pfn(vcpu->kvm, gfn);
+	if (is_error_noslot_pfn(map->pfn))
+		return -EINVAL;
+
+	if (pfn_valid(map->pfn)) {
+		map->page = pfn_to_page(map->pfn);
+		map->hva = kmap(map->page);
+#ifdef CONFIG_HAS_IOMEM
+	} else {
+		map->hva = memremap(pfn_to_hpa(map->pfn), PAGE_SIZE, MEMREMAP_WB);
+#endif
+	}
+
+	return map->hva ? 0 : -EFAULT;
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_map);
 
-- 
2.46.0.rc1.232.g9752f9e123-goog