This is a note to let you know that I've just added the patch titled KVM: x86: Check for existing Hyper-V vCPU in kvm_hv_vcpu_init() to the 6.0-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kvm-x86-check-for-existing-hyper-v-vcpu-in-kvm_hv_vc.patch and it can be found in the queue-6.0 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 2af948a8e9becc744b8a2f1d0718d6e255df8b46 Author: Sean Christopherson <seanjc@xxxxxxxxxx> Date: Tue Aug 30 15:37:08 2022 +0200 KVM: x86: Check for existing Hyper-V vCPU in kvm_hv_vcpu_init() [ Upstream commit 1cac8d9f6bd25df3713103e44e2d9ca0c2e03c33 ] 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@xxxxxxxxxx> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> Reviewed-by: Wei Liu <wei.liu@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220830133737.1539624-5-vkuznets@xxxxxxxxxx Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Stable-dep-of: 3be29eb7b525 ("KVM: x86: Report error when setting CPUID if Hyper-V allocation fails") Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> 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);