[kvm PATCH v2 1/1] kvm: Make VM ioctl do a vzalloc instead of a kzalloc

[Marc Orr <marcorr@xxxxxxxxxx>]

The kvm struct is (currently) tens of kilo-bytes, which turns out to be a
large amount of memory to allocate contiguously via kzalloc. Thus, this
patch changes the kzalloc to a vzalloc, so that the memory allocation is
less likely to fail in resource-constrained environments.

Signed-off-by: Marc Orr <marcorr@xxxxxxxxxx>
Change-Id: Ide392e51991142d1325e06351231ac685e11d820
---
 arch/x86/kvm/svm.c       | 4 ++--
 arch/x86/kvm/vmx.c       | 4 ++--
 include/linux/kvm_host.h | 5 +++--
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b58787daf9f8..f990fda1b2f6 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1838,13 +1838,13 @@ static void __unregister_enc_region_locked(struct kvm *kvm,
 
 static struct kvm *svm_vm_alloc(void)
 {
-	struct kvm_svm *kvm_svm = kzalloc(sizeof(struct kvm_svm), GFP_KERNEL);
+	struct kvm_svm *kvm_svm = vzalloc(sizeof(struct kvm_svm));
 	return &kvm_svm->kvm;
 }
 
 static void svm_vm_free(struct kvm *kvm)
 {
-	kfree(to_kvm_svm(kvm));
+	vfree(to_kvm_svm(kvm));
 }
 
 static void sev_vm_destroy(struct kvm *kvm)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index aafcc9881e88..26ab153a293f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -9949,13 +9949,13 @@ STACK_FRAME_NON_STANDARD(vmx_vcpu_run);
 
 static struct kvm *vmx_vm_alloc(void)
 {
-	struct kvm_vmx *kvm_vmx = kzalloc(sizeof(struct kvm_vmx), GFP_KERNEL);
+	struct kvm_vmx *kvm_vmx = vzalloc(sizeof(struct kvm_vmx));
 	return &kvm_vmx->kvm;
 }
 
 static void vmx_vm_free(struct kvm *kvm)
 {
-	kfree(to_kvm_vmx(kvm));
+	vfree(to_kvm_vmx(kvm));
 }
 
 static void vmx_switch_vmcs(struct kvm_vcpu *vcpu, struct loaded_vmcs *vmcs)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 6930c63126c7..cf7b6a3a4197 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -19,6 +19,7 @@
 #include <linux/preempt.h>
 #include <linux/msi.h>
 #include <linux/slab.h>
+#include <linux/vmalloc.h>
 #include <linux/rcupdate.h>
 #include <linux/ratelimit.h>
 #include <linux/err.h>
@@ -810,12 +811,12 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu);
 #ifndef __KVM_HAVE_ARCH_VM_ALLOC
 static inline struct kvm *kvm_arch_alloc_vm(void)
 {
-	return kzalloc(sizeof(struct kvm), GFP_KERNEL);
+	return vzalloc(sizeof(struct kvm));
 }
 
 static inline void kvm_arch_free_vm(struct kvm *kvm)
 {
-	kfree(kvm);
+	vfree(kvm);
 }
 #endif
 
-- 
2.17.0.441.gb46fe60e1d-goog