From: Vitaly Kuznetsov Check that VMPTRLD when eVMCS is active results in #UD. This matches genuine Hyper-V's behavior. Use KVM_ASM_SAFE framework to handle #UD from VMPTRLD. Unfortunately, the same trick cannot be applied to the existing #UD check on VMLAUNCH as VMLAUNCH clobbers all registers which KVM_ASM_SAFE depends on. Keep VMLAUNCH handling separately. Deliberately use a double-underscores prefix instead of a "safe" postfix for the helper, to communicate that the inner/outer helpers handle more than just exceptions, they also handle VM-Fail conditions. Assisted-by: Claude:claude-sonnet-4-6 Signed-off-by: Vitaly Kuznetsov [sean: use __ instead of _safe] Signed-off-by: Sean Christopherson --- tools/testing/selftests/kvm/include/x86/vmx.h | 19 +++++++++++--- .../testing/selftests/kvm/x86/hyperv_evmcs.c | 26 +++++++++++++++---- 2 files changed, 37 insertions(+), 8 deletions(-) diff --git a/tools/testing/selftests/kvm/include/x86/vmx.h b/tools/testing/selftests/kvm/include/x86/vmx.h index ac7d48d1387e..a161dbee7e04 100644 --- a/tools/testing/selftests/kvm/include/x86/vmx.h +++ b/tools/testing/selftests/kvm/include/x86/vmx.h @@ -342,9 +342,6 @@ static inline int vmptrld(u64 vmcs_pa) { u8 ret; - if (enable_evmcs) - return -1; - __asm__ __volatile__ ("vmptrld %[pa]; setna %[ret]" : [ret]"=rm"(ret) : [pa]"m"(vmcs_pa) @@ -353,6 +350,22 @@ static inline int vmptrld(u64 vmcs_pa) return ret; } +static inline int __vmptrld(u64 vmcs_pa) +{ + u64 error_code; + u8 vector; + u8 failed; + + asm volatile(KVM_ASM_SAFE("vmptrld %[pa]") + "\n\tsetna %[failed]" + : KVM_ASM_SAFE_OUTPUTS(vector, error_code), + [failed]"=qm"(failed) + : [pa]"m"(vmcs_pa) + : "cc", "memory", KVM_ASM_SAFE_CLOBBERS); + + return vector ? vector : failed ? -EINVAL : 0; +} + static inline int vmptrst(u64 *value) { u64 tmp; diff --git a/tools/testing/selftests/kvm/x86/hyperv_evmcs.c b/tools/testing/selftests/kvm/x86/hyperv_evmcs.c index 6224d859d7bb..f953a9755a76 100644 --- a/tools/testing/selftests/kvm/x86/hyperv_evmcs.c +++ b/tools/testing/selftests/kvm/x86/hyperv_evmcs.c @@ -23,7 +23,11 @@ static int ud_count; static void guest_ud_handler(struct ex_regs *regs) { ud_count++; - regs->rip += 3; /* VMLAUNCH */ + /* + * VMLAUNCH insn can't be easily covered by KVM_ASM_SAFE framework but + * luckily the instruction is always three bytes. + */ + regs->rip += 3; } static void guest_nmi_handler(struct ex_regs *regs) @@ -178,7 +182,15 @@ void guest_code(struct vmx_pages *vmx_pages, struct hyperv_test_pages *hv_pages, GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL); GUEST_SYNC(11); - /* Try enlightened vmptrld with an incorrect GPA */ + /* VMPTRLD instruction causes #UD after enlightened VMLAUNCH */ + GUEST_ASSERT(__vmptrld(hv_pages->enlightened_vmcs_gpa) == UD_VECTOR); + + /* + * Try enlightened vmptrld with an incorrect GPA. GUEST_SYNC(12) signals + * the host to enable guest_ud_handler() which cannot be enabled beforehand + * to not override the default fixup handler from KVM_ASM_SAFE(). + */ + GUEST_SYNC(12); evmcs_vmptrld(0xdeadbeef, hv_pages->enlightened_vmcs); GUEST_ASSERT(vmlaunch()); GUEST_ASSERT(ud_count == 1); @@ -252,7 +264,6 @@ int main(int argc, char *argv[]) vcpu_args_set(vcpu, 3, vmx_pages_gva, hv_pages_gva, addr_gva2gpa(vm, hcall_page)); vcpu_set_msr(vcpu, HV_X64_MSR_VP_INDEX, vcpu->id); - vm_install_exception_handler(vm, UD_VECTOR, guest_ud_handler); vm_install_exception_handler(vm, NMI_VECTOR, guest_nmi_handler); pr_info("Running L1 which uses EVMCS to run L2\n"); @@ -282,7 +293,7 @@ int main(int argc, char *argv[]) /* Force immediate L2->L1 exit before resuming */ if (stage == 8) { - pr_info("Injecting NMI into L1 before L2 had a chance to run after restore\n"); + pr_debug("Injecting NMI into L1 before L2 had a chance to run after restore\n"); inject_nmi(vcpu); } @@ -292,9 +303,14 @@ int main(int argc, char *argv[]) * KVM_STATE_NESTED_EVMCS is not lost. */ if (stage == 9) { - pr_info("Trying extra KVM_GET_NESTED_STATE/KVM_SET_NESTED_STATE cycle\n"); + pr_debug("Trying extra KVM_GET_NESTED_STATE/KVM_SET_NESTED_STATE cycle\n"); vcpu = save_restore_vm(vm, vcpu); } + + if (stage == 12) { + pr_debug("Trying enlightened VMLAUNCH with an invalid PTR\n"); + vm_install_exception_handler(vm, UD_VECTOR, guest_ud_handler); + } } done: -- 2.55.0.887.g758fc8c411-goog