Re: [PATCH v2 2/3] KVM: TDX: Synthesize SHUTDOWN instead of returning -EIO on unhandled EPT violation

[Binbin Wu <binbin.wu@linux.intel.com>]

On 9/30/2026 8:11 AM, Sean Christopherson wrote:
> Exit to userspace with KVM_EXIT_SHUTDOWN instead of returning -EIO from
> KVM_RUN if KVM encounters an EPT Violation due to a guest access to a
> pending page.  Returning -EIO implies KVM is buggy, and most VMMs will
> respond by completely terminating the VM, versus rebooting the VM in
> response to KVM_EXIT_SHUTDOWN.  I.e. give the VMM the option of trying to
> keep the VM (from the end user's perspective) alive.
> 
> Ideally, KVM would probably exit with KVM_EXIT_MEMORY_FAULT, but KVM would
> need to extend run->memory_fault so that userspace knows the fault can't be
> handled.  This scenario specifically occurs when the guest has deliberately
> disabled #VEs on unaccepted memory for security purposes, i.e. the guest
> literally disabled the mechanism that tells it it screwed up.  But, because
> this is fatal, and the whole point is to NOT try to fixup the fault,
> jumping through hoops to return MEMORY_FAULT instead of SHUTDOWN doesn't
> make a whole lot of sense.
> 
> Don't bother bouncing through KVM_REQ_TRIPLE_FAULT as
> tdx_handle_ept_violation() is a top-level exit handler, i.e. there is no
> need to worry about failing to actually exit to userspace.
> 
> Fixes: e6a85781f783 ("KVM: TDX: Detect unexpected SEPT violations due to pending SPTEs")
> Cc: stable@vger.kernel.org
> Cc: James Houghton <jthoughton@google.com>
> Cc: Xiaoyao Li <xiaoyao.li@intel.com>
> Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
> Cc: Yan Zhao <yan.y.zhao@intel.com>
> Cc: Binbin Wu <binbin.wu@linux.intel.com>
> Cc: Ackerley Tng <ackerleytng@google.com>
> Cc: Vishal Annapurve <vannapurve@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>

> ---
>  arch/x86/kvm/vmx/tdx.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 29d4751f37fb..e3723f1222fc 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -1939,8 +1939,8 @@ static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu)
>  		if (tdx_is_sept_violation_unexpected_pending(vcpu)) {
>  			pr_warn("Guest access before accepting 0x%llx on vCPU %d\n",
>  				gpa, vcpu->vcpu_id);
> -			kvm_vm_dead(vcpu->kvm);
> -			return -EIO;
> +			kvm_prepare_shutdown_exit(vcpu);
> +			return 0;
>  		}
>  		/*
>  		 * Always treat SEPT violations as write faults.  Ignore the