Re: [PATCH v5 3/3] KVM: selftests: Add self IPI HLT test

[Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>]

On 1/3/2025 1:48 PM, Manali Shukla wrote:
> From: Manali Shukla <Manali.Shukla@amd.com>
> 
> The IPI HLT test simulates a scenario where a pending event is present
> while the HLT instruction is executed.
> 
> Evaluates the idle HLT intercept feature of the AMD architecture, if

Nit: Start as "The test evaluates idle HLT intercept feature ..." ?

> available. If the feature is not present, this selftest can be extended

If idle halt intercept feature is not present the test exercises
halt-exits/guest-entry for pending interrupts. So, maybe the test in
its current form is still useful if idle halt intercept feature is
not present. Is that understanding wrong? Cross-vCPU IPI or performance
testing of halt exits are future extensions to this test.

> in the future to include cross-vCPU IPI testing.
> 
> Suggested-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Manali Shukla <Manali.Shukla@amd.com>
> ---
>  tools/testing/selftests/kvm/Makefile.kvm      |  1 +
>  .../selftests/kvm/include/x86/processor.h     |  1 +
>  tools/testing/selftests/kvm/ipi_hlt_test.c    | 83 +++++++++++++++++++
>  3 files changed, 85 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/ipi_hlt_test.c
> 
> diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
> index 4277b983cace..d6eda8c19fed 100644
> --- a/tools/testing/selftests/kvm/Makefile.kvm
> +++ b/tools/testing/selftests/kvm/Makefile.kvm
> @@ -135,6 +135,7 @@ TEST_GEN_PROGS_x86 += steal_time
>  TEST_GEN_PROGS_x86 += kvm_binary_stats_test
>  TEST_GEN_PROGS_x86 += system_counter_offset_test
>  TEST_GEN_PROGS_x86 += pre_fault_memory_test
> +TEST_GEN_PROGS_x86 += ipi_hlt_test
>  
>  # Compiled outputs used by test targets
>  TEST_GEN_PROGS_EXTENDED_x86 += x86/nx_huge_pages_test
> diff --git a/tools/testing/selftests/kvm/include/x86/processor.h b/tools/testing/selftests/kvm/include/x86/processor.h
> index 1f9798ed71f1..23a34a12be48 100644
> --- a/tools/testing/selftests/kvm/include/x86/processor.h
> +++ b/tools/testing/selftests/kvm/include/x86/processor.h
> @@ -197,6 +197,7 @@ struct kvm_x86_cpu_feature {
>  #define X86_FEATURE_PAUSEFILTER         KVM_X86_CPU_FEATURE(0x8000000A, 0, EDX, 10)
>  #define X86_FEATURE_PFTHRESHOLD         KVM_X86_CPU_FEATURE(0x8000000A, 0, EDX, 12)
>  #define	X86_FEATURE_VGIF		KVM_X86_CPU_FEATURE(0x8000000A, 0, EDX, 16)
> +#define X86_FEATURE_IDLE_HLT		KVM_X86_CPU_FEATURE(0x8000000A, 0, EDX, 30)
>  #define X86_FEATURE_SEV			KVM_X86_CPU_FEATURE(0x8000001F, 0, EAX, 1)
>  #define X86_FEATURE_SEV_ES		KVM_X86_CPU_FEATURE(0x8000001F, 0, EAX, 3)
>  
> diff --git a/tools/testing/selftests/kvm/ipi_hlt_test.c b/tools/testing/selftests/kvm/ipi_hlt_test.c
> new file mode 100644
> index 000000000000..09ed8011450f
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/ipi_hlt_test.c
> @@ -0,0 +1,83 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + *  Copyright (C) 2024 Advanced Micro Devices, Inc.
> + *
> + */
> +#include <kvm_util.h>
> +#include <processor.h>
> +#include <test_util.h>
> +#include "apic.h"
> +
> +#define INTR_VECTOR     0x30
> +#define NUM_ITERATIONS   1000
> +
> +static bool irq_received;
> +
> +/*
> + * The guest code instruments the scenario where there is a V_INTR pending
> + * event available while hlt instruction is executed.
> + */
> +
> +static void guest_code(void)
> +{
> +	uint32_t icr_val;

uint64_t ?

> +	int i;
> +
> +	x2apic_enable();
> +
> +	icr_val = (APIC_DEST_SELF | APIC_INT_ASSERT | INTR_VECTOR);
> +
> +	for (i = 0; i < NUM_ITERATIONS; i++) {
> +		cli();
> +		x2apic_write_reg(APIC_ICR, icr_val);
> +		safe_halt();
> +		GUEST_ASSERT(READ_ONCE(irq_received));
> +		WRITE_ONCE(irq_received, false);
> +	}
> +	GUEST_DONE();
> +}
> +
> +static void guest_vintr_handler(struct ex_regs *regs)

s/guest_vintr_handler/guest_intr_handler/ ?


> +{
> +	WRITE_ONCE(irq_received, true);
> +	x2apic_write_reg(APIC_EOI, 0x00);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	struct kvm_vm *vm;
> +	struct kvm_vcpu *vcpu;
> +	struct ucall uc;
> +	uint64_t  halt_exits;

Extra space

> +
> +	TEST_REQUIRE(kvm_has_cap(KVM_CAP_BINARY_STATS_FD));
> +
> +	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
> +
> +	vm_install_exception_handler(vm, INTR_VECTOR, guest_vintr_handler);
> +	virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA);

virt_pg_map() is not required for x2apic. So, remove?

> +
> +	vcpu_run(vcpu);
> +	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
> +
> +	halt_exits = vcpu_get_stat(vcpu, halt_exits);
> +
> +	switch (get_ucall(vcpu, &uc)) {
> +	case UCALL_ABORT:
> +		REPORT_GUEST_ASSERT(uc);
> +		/* NOT REACHED */
> +	case UCALL_DONE:
> +		break;
> +

Nit: empty line not required?


- Neeraj

> +	default:
> +		TEST_FAIL("Unknown ucall 0x%lx.", uc.cmd);
> +	}
> +
> +	if (kvm_cpu_has(X86_FEATURE_IDLE_HLT))
> +		TEST_ASSERT_EQ(halt_exits, 0);
> +	else
> +		TEST_ASSERT_EQ(halt_exits, NUM_ITERATIONS);
> +
> +	kvm_vm_free(vm);
> +	return 0;
> +}