linux-kernel - [PATCH 2/3] KVM: x86: Allocate kvm_vmx/kvm

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Message-ID: <20250315024010.2360884-3-seanjc@google.com>
Date: Fri, 14 Mar 2025 19:40:09 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] KVM: x86: Allocate kvm_vmx/kvm_svm structures using kzalloc()

Now that the size of "struct kvm" is less than 2KiB, switch back to using
kzalloc() to allocate the VM structures.  Add compile-time assertions in
vendor code to ensure the size is an order-0 allocation, i.e. to prevent
unknowingly letting the size balloon in the future.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/include/asm/kvm_host.h | 2 +-
 arch/x86/kvm/svm/svm.c          | 1 +
 arch/x86/kvm/vmx/vmx.c          | 1 +
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 6ead9e57446a..04e6c5604bc3 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1939,7 +1939,7 @@ void kvm_x86_vendor_exit(void);
 #define __KVM_HAVE_ARCH_VM_ALLOC
 static inline struct kvm *kvm_arch_alloc_vm(void)
 {
-	return __vmalloc(kvm_x86_ops.vm_size, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+	return kzalloc(kvm_x86_ops.vm_size, GFP_KERNEL_ACCOUNT);
 }
 
 #define __KVM_HAVE_ARCH_VM_FREE
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 8abeab91d329..589adc5f92e0 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -5536,6 +5536,7 @@ static int __init svm_init(void)
 	if (r)
 		goto err_kvm_init;
 
+	BUILD_BUG_ON(get_order(sizeof(struct kvm_svm) != 0));
 	return 0;
 
 err_kvm_init:
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index b70ed72c1783..01264842bf45 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8755,6 +8755,7 @@ static int __init vmx_init(void)
 	if (r)
 		goto err_kvm_init;
 
+	BUILD_BUG_ON(get_order(sizeof(struct kvm_vmx) != 0));
 	return 0;
 
 err_kvm_init:
-- 
2.49.0.rc1.451.g8f38331e32-goog