Hi Isaku, On 4/3/2024 11:42 AM, Isaku Yamahata wrote: > On Mon, Apr 01, 2024 at 12:10:58PM +0800, > Chao Gao <chao.gao@xxxxxxxxx> wrote: > >>> +static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu) >>> +{ >>> + unsigned long exit_qual; >>> + >>> + if (kvm_is_private_gpa(vcpu->kvm, tdexit_gpa(vcpu))) { >>> + /* >>> + * Always treat SEPT violations as write faults. Ignore the >>> + * EXIT_QUALIFICATION reported by TDX-SEAM for SEPT violations. >>> + * TD private pages are always RWX in the SEPT tables, >>> + * i.e. they're always mapped writable. Just as importantly, >>> + * treating SEPT violations as write faults is necessary to >>> + * avoid COW allocations, which will cause TDAUGPAGE failures >>> + * due to aliasing a single HPA to multiple GPAs. >>> + */ >>> +#define TDX_SEPT_VIOLATION_EXIT_QUAL EPT_VIOLATION_ACC_WRITE >>> + exit_qual = TDX_SEPT_VIOLATION_EXIT_QUAL; >>> + } else { >>> + exit_qual = tdexit_exit_qual(vcpu); >>> + if (exit_qual & EPT_VIOLATION_ACC_INSTR) { >> >> Unless the CPU has a bug, instruction fetch in TD from shared memory causes a >> #PF. I think you can add a comment for this. > > Yes. > > >> Maybe KVM_BUG_ON() is more appropriate as it signifies a potential bug. > > Bug of what component? CPU. If so, I think KVM_EXIT_INTERNAL_ERROR + > KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON is more appropriate. > Is below what you have in mind? diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 499c6cd9633f..bd30b4c4d710 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -1305,11 +1305,18 @@ static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu) } else { exit_qual = tdexit_exit_qual(vcpu); if (exit_qual & EPT_VIOLATION_ACC_INSTR) { + /* + * Instruction fetch in TD from shared memory + * causes a #PF. + */ pr_warn("kvm: TDX instr fetch to shared GPA = 0x%lx @ RIP = 0x%lx\n", tdexit_gpa(vcpu), kvm_rip_read(vcpu)); - vcpu->run->exit_reason = KVM_EXIT_EXCEPTION; - vcpu->run->ex.exception = PF_VECTOR; - vcpu->run->ex.error_code = exit_qual; + vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; + vcpu->run->internal.suberror = + KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON; + vcpu->run->internal.ndata = 2; + vcpu->run->internal.data[0] = EXIT_REASON_EPT_VIOLATION; + vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu; return 0; } } Thank you Reinette