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Message-ID: <1f9d2b41-95ad-42ca-b1e5-70212b93a9c1@linux.intel.com>
Date: Sat, 2 Mar 2024 15:31:07 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: Sagi Shahar <sagis@...gle.com>
Cc: linux-kselftest@...r.kernel.org, Ackerley Tng <ackerleytng@...gle.com>,
Ryan Afranji <afranji@...gle.com>, Erdem Aktas <erdemaktas@...gle.com>,
Isaku Yamahata <isaku.yamahata@...el.com>,
Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini
<pbonzini@...hat.com>, Shuah Khan <shuah@...nel.org>,
Peter Gonda <pgonda@...gle.com>, Haibo Xu <haibo1.xu@...el.com>,
Chao Peng <chao.p.peng@...ux.intel.com>,
Vishal Annapurve <vannapurve@...gle.com>, Roger Wang <runanwang@...gle.com>,
Vipin Sharma <vipinsh@...gle.com>, jmattson@...gle.com, dmatlack@...gle.com,
linux-kernel@...r.kernel.org, kvm@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [RFC PATCH v5 16/29] KVM: selftests: TDX: Add TDX HLT exit test
On 12/13/2023 4:46 AM, Sagi Shahar wrote:
> The test verifies that the guest runs TDVMCALL<INSTRUCTION.HLT> and the
> guest vCPU enters to the halted state.
>
> Signed-off-by: Erdem Aktas <erdemaktas@...gle.com>
> Signed-off-by: Sagi Shahar <sagis@...gle.com>
> Signed-off-by: Ackerley Tng <ackerleytng@...gle.com>
> Signed-off-by: Ryan Afranji <afranji@...gle.com>
> ---
> .../selftests/kvm/include/x86_64/tdx/tdx.h | 2 +
> .../selftests/kvm/lib/x86_64/tdx/tdx.c | 10 +++
> .../selftests/kvm/x86_64/tdx_vm_tests.c | 78 +++++++++++++++++++
> 3 files changed, 90 insertions(+)
>
> diff --git a/tools/testing/selftests/kvm/include/x86_64/tdx/tdx.h b/tools/testing/selftests/kvm/include/x86_64/tdx/tdx.h
> index 85ba6aab79a7..b18e39d20498 100644
> --- a/tools/testing/selftests/kvm/include/x86_64/tdx/tdx.h
> +++ b/tools/testing/selftests/kvm/include/x86_64/tdx/tdx.h
> @@ -8,6 +8,7 @@
> #define TDG_VP_VMCALL_GET_TD_VM_CALL_INFO 0x10000
> #define TDG_VP_VMCALL_REPORT_FATAL_ERROR 0x10003
>
> +#define TDG_VP_VMCALL_INSTRUCTION_HLT 12
> #define TDG_VP_VMCALL_INSTRUCTION_IO 30
> #define TDG_VP_VMCALL_INSTRUCTION_RDMSR 31
> #define TDG_VP_VMCALL_INSTRUCTION_WRMSR 32
> @@ -20,5 +21,6 @@ uint64_t tdg_vp_vmcall_get_td_vmcall_info(uint64_t *r11, uint64_t *r12,
> uint64_t *r13, uint64_t *r14);
> uint64_t tdg_vp_vmcall_instruction_rdmsr(uint64_t index, uint64_t *ret_value);
> uint64_t tdg_vp_vmcall_instruction_wrmsr(uint64_t index, uint64_t value);
> +uint64_t tdg_vp_vmcall_instruction_hlt(uint64_t interrupt_blocked_flag);
>
> #endif // SELFTEST_TDX_TDX_H
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx.c b/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx.c
> index 88ea6f2a6469..9485bafedc38 100644
> --- a/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx.c
> +++ b/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx.c
> @@ -114,3 +114,13 @@ uint64_t tdg_vp_vmcall_instruction_wrmsr(uint64_t index, uint64_t value)
>
> return __tdx_hypercall(&args, 0);
> }
> +
> +uint64_t tdg_vp_vmcall_instruction_hlt(uint64_t interrupt_blocked_flag)
> +{
> + struct tdx_hypercall_args args = {
> + .r11 = TDG_VP_VMCALL_INSTRUCTION_HLT,
> + .r12 = interrupt_blocked_flag,
> + };
> +
> + return __tdx_hypercall(&args, 0);
> +}
> diff --git a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
> index 5db3701cc6d9..5fae4c6e5f95 100644
> --- a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
> +++ b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
> @@ -721,6 +721,83 @@ void verify_guest_msr_writes(void)
> printf("\t ... PASSED\n");
> }
>
> +/*
> + * Verifies HLT functionality.
> + */
> +void guest_hlt(void)
> +{
> + uint64_t ret;
> + uint64_t interrupt_blocked_flag;
> +
> + interrupt_blocked_flag = 0;
> + ret = tdg_vp_vmcall_instruction_hlt(interrupt_blocked_flag);
> + if (ret)
> + tdx_test_fatal(ret);
> +
> + tdx_test_success();
> +}
> +
> +void _verify_guest_hlt(int signum);
> +
> +void wake_me(int interval)
> +{
> + struct sigaction action;
> +
> + action.sa_handler = _verify_guest_hlt;
> + sigemptyset(&action.sa_mask);
> + action.sa_flags = 0;
> +
> + TEST_ASSERT(sigaction(SIGALRM, &action, NULL) == 0,
> + "Could not set the alarm handler!");
> +
> + alarm(interval);
> +}
> +
> +void _verify_guest_hlt(int signum)
> +{
> + struct kvm_vm *vm;
> + static struct kvm_vcpu *vcpu;
> +
> + /*
> + * This function will also be called by SIGALRM handler to check the
> + * vCPU MP State. If vm has been initialized, then we are in the signal
> + * handler. Check the MP state and let the guest run again.
> + */
> + if (vcpu != NULL) {
What if the following case if there is a bug in KVM so that:
In guest, execution of tdg_vp_vmcall_instruction_hlt() return 0, but the
vcpu is not actually halted. Then guest will call tdx_test_success().
And the first call of _verify_guest_hlt() will call kvm_vm_free(vm) to free
the vm, which also frees the vcpu, and 1 second later, in this path vcpu
will
be accessed after free.
> + struct kvm_mp_state mp_state;
> +
> + vcpu_mp_state_get(vcpu, &mp_state);
> + TEST_ASSERT_EQ(mp_state.mp_state, KVM_MP_STATE_HALTED);
> +
> + /* Let the guest to run and finish the test.*/
> + mp_state.mp_state = KVM_MP_STATE_RUNNABLE;
> + vcpu_mp_state_set(vcpu, &mp_state);
> + return;
> + }
> +
> + vm = td_create();
> + td_initialize(vm, VM_MEM_SRC_ANONYMOUS, 0);
> + vcpu = td_vcpu_add(vm, 0, guest_hlt);
> + td_finalize(vm);
> +
> + printf("Verifying HLT:\n");
> +
> + printf("\t ... Running guest\n");
> +
> + /* Wait 1 second for guest to execute HLT */
> + wake_me(1);
> + td_vcpu_run(vcpu);
> +
> + TDX_TEST_ASSERT_SUCCESS(vcpu);
> +
> + kvm_vm_free(vm);
> + printf("\t ... PASSED\n");
> +}
> +
> +void verify_guest_hlt(void)
> +{
> + _verify_guest_hlt(0);
> +}
>
> int main(int argc, char **argv)
> {
> @@ -740,6 +817,7 @@ int main(int argc, char **argv)
> run_in_new_process(&verify_guest_reads);
> run_in_new_process(&verify_guest_msr_writes);
> run_in_new_process(&verify_guest_msr_reads);
> + run_in_new_process(&verify_guest_hlt);
>
> return 0;
> }
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