diff mbox series

[v6,04/33] KVM: x86: Check for existing Hyper-V vCPU in kvm_hv_vcpu_init()

Message ID 20220830133737.1539624-5-vkuznets@redhat.com (mailing list archive)
State New, archived
Headers show
Series KVM: VMX: Support updated eVMCSv1 revision + use vmcs_config for L1 VMX MSRs | expand

Commit Message

Vitaly Kuznetsov Aug. 30, 2022, 1:37 p.m. UTC 
From: Sean Christopherson <seanjc@google.com>

When potentially allocating/initializing the Hyper-V vCPU struct, check
for an existing instance in kvm_hv_vcpu_init() instead of requiring
callers to perform the check.  Relying on callers to do the check is
risky as it's all too easy for KVM to overwrite vcpu->arch.hyperv and
leak memory, and it adds additional burden on callers without much
benefit.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/kvm/hyperv.c | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

Comments

Wei Liu Sept. 5, 2022, 5:08 p.m. UTC | #1 
On Tue, Aug 30, 2022 at 03:37:08PM +0200, Vitaly Kuznetsov wrote:
> From: Sean Christopherson <seanjc@google.com>
> 
> When potentially allocating/initializing the Hyper-V vCPU struct, check
> for an existing instance in kvm_hv_vcpu_init() instead of requiring
> callers to perform the check.  Relying on callers to do the check is
> risky as it's all too easy for KVM to overwrite vcpu->arch.hyperv and
> leak memory, and it adds additional burden on callers without much
> benefit.
> 
> No functional change intended.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Reviewed-by: Wei Liu <wei.liu@kernel.org>
diff mbox series

Patch

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 611c349a08bf..8aadd31ed058 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -936,9 +936,12 @@  static void stimer_init(struct kvm_vcpu_hv_stimer *stimer, int timer_index)
 
 static int kvm_hv_vcpu_init(struct kvm_vcpu *vcpu)
 {
-	struct kvm_vcpu_hv *hv_vcpu;
+	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
 	int i;
 
+	if (hv_vcpu)
+		return 0;
+
 	hv_vcpu = kzalloc(sizeof(struct kvm_vcpu_hv), GFP_KERNEL_ACCOUNT);
 	if (!hv_vcpu)
 		return -ENOMEM;
@@ -962,11 +965,9 @@  int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages)
 	struct kvm_vcpu_hv_synic *synic;
 	int r;
 
-	if (!to_hv_vcpu(vcpu)) {
-		r = kvm_hv_vcpu_init(vcpu);
-		if (r)
-			return r;
-	}
+	r = kvm_hv_vcpu_init(vcpu);
+	if (r)
+		return r;
 
 	synic = to_hv_synic(vcpu);
 
@@ -1660,10 +1661,8 @@  int kvm_hv_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
 	if (!host && !vcpu->arch.hyperv_enabled)
 		return 1;
 
-	if (!to_hv_vcpu(vcpu)) {
-		if (kvm_hv_vcpu_init(vcpu))
-			return 1;
-	}
+	if (kvm_hv_vcpu_init(vcpu))
+		return 1;
 
 	if (kvm_hv_msr_partition_wide(msr)) {
 		int r;
@@ -1683,10 +1682,8 @@  int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host)
 	if (!host && !vcpu->arch.hyperv_enabled)
 		return 1;
 
-	if (!to_hv_vcpu(vcpu)) {
-		if (kvm_hv_vcpu_init(vcpu))
-			return 1;
-	}
+	if (kvm_hv_vcpu_init(vcpu))
+		return 1;
 
 	if (kvm_hv_msr_partition_wide(msr)) {
 		int r;
@@ -2000,7 +1997,7 @@  void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu)
 		return;
 	}
 
-	if (!to_hv_vcpu(vcpu) && kvm_hv_vcpu_init(vcpu))
+	if (kvm_hv_vcpu_init(vcpu))
 		return;
 
 	hv_vcpu = to_hv_vcpu(vcpu);