Re: [kvm-unit-tests PATCH V2 10/10] x86/svm: Add test for #UD when EFER.SVME=0

[Sean Christopherson <seanjc@google.com>]

On Tue, Jan 13, 2026, Kevin Cheng wrote:
> +static void svm_ud_test_handler(struct ex_regs *regs)
> +{
> +	ud_fired = true;
> +	regs->rip += 3;
> +}
> +
> +static void svm_ud_test(void)
> +{
> +	u64 efer = rdmsr(MSR_EFER);
> +
> +	handle_exception(UD_VECTOR, svm_ud_test_handler);
> +	wrmsr(MSR_EFER, efer & ~EFER_SVME);
> +
> +	insn_invlpga();

Eh, just add proper helpers, or open code the asm.  And definitely use asm_safe()
instead of wiring up a dedicated #UD handler.  Ha!  And past me even proactively
waged war on copy+paste exception handling.

Untested, but something like this should work.

	asm_safe_report_ex("invlpga %rax, %ecx", "a"(0), "c"(0));
	asm_safe_report_ex("vmrun %rax", "a"(0));
	asm_safe_report_ex("vmsave %rax", "a"(0));
	asm_safe_report_ex("vmload %rax", "a"(0));

> diff --git a/x86/unittests.cfg b/x86/unittests.cfg
> index 118e7cdd0286d..ad447e5f82f9f 100644
> --- a/x86/unittests.cfg
> +++ b/x86/unittests.cfg
> @@ -253,11 +253,19 @@ arch = x86_64
>  [svm]
>  file = svm.flat
>  smp = 2
> -test_args = "-pause_filter_test -svm_intr_intercept_mix_smi -svm_insn_intercept_test -svm_pf_exception_test -svm_pf_exception_forced_emulation_test -svm_pf_inv_asid_test -svm_pf_inv_tlb_ctl_test -svm_event_injection"
> +test_args = "-pause_filter_test -svm_intr_intercept_mix_smi -svm_insn_intercept_test -svm_pf_exception_test -svm_pf_exception_forced_emulation_test -svm_pf_inv_asid_test -svm_pf_inv_tlb_ctl_test -svm_event_injection -svm_ud_test"
>  qemu_params = -cpu max,+svm -m 4g
>  arch = x86_64
>  groups = svm
>  
> +# Disable SKINIT and SVML to test STGI #UD when EFER.SVME=0
> +[svm_ud_test]
> +file = svm.flat
> +test_args = svm_ud_test
> +qemu_params = -cpu max,-skinit,-svm-lock,+svm -m 4g

KVM doesn't support SKINIT or SVM-LOCK, carving out a separate config just to
disable things that aren't supported is pointless.  If QEMU TCG gets false
failures due to its default model emulating the interactions with SKINIT and/or
SVM-LOCK, then I'd prefer to account for that in the test, not in the config. 

> +arch = x86_64
> +groups = svm
> +
>  [svm_event_injection]
>  file = svm.flat
>  test_args = svm_event_injection
> -- 
> 2.52.0.457.g6b5491de43-goog
>