From: Sean Christopherson <seanjc@xxxxxxxxxx> Avoid local retries within the TDX EPT violation handler if a retry is triggered by faulting in an invalid memslot, indicating that the memslot is undergoing a removal process. This prevents the slot removal process from being blocked while waiting for the VMExit handler to release the SRCU lock. Opportunistically, export symbol kvm_vcpu_gfn_to_memslot() to allow for per-vCPU acceleration of gfn_to_memslot translation. [Yan: Wrote patch log, comment, fixed a minor error, function export] Reported-by: Reinette Chatre <reinette.chatre@xxxxxxxxx> Closes: https://lore.kernel.org/all/20250519023737.30360-1-yan.y.zhao@xxxxxxxxx Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx> --- arch/x86/kvm/vmx/tdx.c | 11 +++++++++++ virt/kvm/kvm_main.c | 1 + 2 files changed, 12 insertions(+) diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 6784aaaced87..de2c4bb36069 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -1992,6 +1992,11 @@ static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu) * blocked by TDs, false positives are inevitable i.e., KVM may re-enter * the guest even if the IRQ/NMI can't be delivered. * + * Breaking out of the local retries if a retry is caused by faulting + * in an invalid memslot (indicating the slot is under removal), so that + * the slot removal will not be blocked due to waiting for releasing + * SRCU lock in the VMExit handler. + * * Note: even without breaking out of local retries, zero-step * mitigation may still occur due to * - invoking of TDH.VP.ENTER after KVM_EXIT_MEMORY_FAULT, @@ -2002,6 +2007,8 @@ static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu) * handle retries locally in their EPT violation handlers. */ while (1) { + struct kvm_memory_slot *slot; + ret = __vmx_handle_ept_violation(vcpu, gpa, exit_qual); if (ret != RET_PF_RETRY || !local_retry) @@ -2015,6 +2022,10 @@ static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu) break; } + slot = kvm_vcpu_gfn_to_memslot(vcpu, gpa_to_gfn(gpa)); + if (slot && slot->flags & KVM_MEMSLOT_INVALID) + break; + cond_resched(); } return ret; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 6c07dd423458..f769d1dccc21 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2661,6 +2661,7 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn return NULL; } +EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_memslot); bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn) { -- 2.43.2
