| Message ID | 20240828232013.768446-1-seanjc@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: Ensure vcpu->mode is loaded from memory in kvm_vcpu_exit_request() | expand |
On Wed, 28 Aug 2024 16:20:13 -0700, Sean Christopherson wrote: > Wrap kvm_vcpu_exit_request()'s load of vcpu->mode with READ_ONCE() to > ensure the variable is re-loaded from memory, as there is no guarantee the > caller provides the necessary annotations to ensure KVM sees a fresh value, > e.g. the VM-Exit fastpath could theoretically reuse the pre-VM-Enter value. Applied to kvm-x86 misc, thanks! [1/1] KVM: x86: Ensure vcpu->mode is loaded from memory in kvm_vcpu_exit_request() https://github.com/kvm-x86/linux/commit/ba50bb4a9fb5 -- https://github.com/kvm-x86/linux/tree/next
On Thu, Oct 31, 2024, Sean Christopherson wrote: > On Wed, 28 Aug 2024 16:20:13 -0700, Sean Christopherson wrote: > > Wrap kvm_vcpu_exit_request()'s load of vcpu->mode with READ_ONCE() to > > ensure the variable is re-loaded from memory, as there is no guarantee the > > caller provides the necessary annotations to ensure KVM sees a fresh value, > > e.g. the VM-Exit fastpath could theoretically reuse the pre-VM-Enter value. > > Applied to kvm-x86 misc, thanks! > > [1/1] KVM: x86: Ensure vcpu->mode is loaded from memory in kvm_vcpu_exit_request() > https://github.com/kvm-x86/linux/commit/ba50bb4a9fb5 FYI, I rebased misc to v6.12-rc5, as patches in another series had already been taken through the tip tree. New hash: [1/1] KVM: x86: Ensure vcpu->mode is loaded from memory in kvm_vcpu_exit_request() https://github.com/kvm-x86/linux/commit/3ffe874ea3eb
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 70219e406987..d38fdb5f90dd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2124,8 +2124,9 @@ EXPORT_SYMBOL_GPL(kvm_emulate_monitor); static inline bool kvm_vcpu_exit_request(struct kvm_vcpu *vcpu) { xfer_to_guest_mode_prepare(); - return vcpu->mode == EXITING_GUEST_MODE || kvm_request_pending(vcpu) || - xfer_to_guest_mode_work_pending(); + + return READ_ONCE(vcpu->mode) == EXITING_GUEST_MODE || + kvm_request_pending(vcpu) || xfer_to_guest_mode_work_pending(); } /*
Wrap kvm_vcpu_exit_request()'s load of vcpu->mode with READ_ONCE() to ensure the variable is re-loaded from memory, as there is no guarantee the caller provides the necessary annotations to ensure KVM sees a fresh value, e.g. the VM-Exit fastpath could theoretically reuse the pre-VM-Enter value. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/x86.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) base-commit: 15e1c3d65975524c5c792fcd59f7d89f00402261