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Date: Thu, 18 Mar 2021 17:20:36 +0100
From: Andrew Jones <drjones@...hat.com>
To: Emanuele Giuseppe Esposito <eesposit@...hat.com>
Cc: linux-kselftest@...r.kernel.org,
Paolo Bonzini <pbonzini@...hat.com>,
Shuah Khan <shuah@...nel.org>, Peter Xu <peterx@...hat.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v2 2/2] selftests/kvm: add set_boot_cpu_id test
On Thu, Mar 18, 2021 at 04:16:24PM +0100, Emanuele Giuseppe Esposito wrote:
> Test for the KVM_SET_BOOT_CPU_ID ioctl.
> Check that it correctly allows to change the BSP vcpu.
>
> v1 -> v2:
> - remove unnecessary printf
> - move stage for loop inside run_vcpu
> - test EBUSY when calling KVM_SET_BOOT_CPU_ID after vcpu
> creation and execution
> - introduce _vm_ioctl
This information should be in the cover-letter. Or, for a single patch (no
cover-letter needed submission), then it should go below the '---' under
your s-o-b.
>
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@...hat.com>
> ---
> tools/testing/selftests/kvm/.gitignore | 1 +
> tools/testing/selftests/kvm/Makefile | 1 +
> .../selftests/kvm/x86_64/set_boot_cpu_id.c | 166 ++++++++++++++++++
> 3 files changed, 168 insertions(+)
> create mode 100644 tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c
>
> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
> index 32b87cc77c8e..43b8aa82aefe 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -5,6 +5,7 @@
> /s390x/resets
> /s390x/sync_regs_test
> /x86_64/cr4_cpuid_sync_test
> +/x86_64/set_boot_cpu_id
> /x86_64/debug_regs
> /x86_64/evmcs_test
> /x86_64/get_cpuid_test
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index a6d61f451f88..e7b62666e06e 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -39,6 +39,7 @@ LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c
> LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c lib/s390x/diag318_test_handler.c
>
> TEST_GEN_PROGS_x86_64 = x86_64/cr4_cpuid_sync_test
> +TEST_GEN_PROGS_x86_64 += x86_64/set_boot_cpu_id
We like the above two test lists (Makefile and .gitignore) to be in
alphabetical order.
> TEST_GEN_PROGS_x86_64 += x86_64/evmcs_test
> TEST_GEN_PROGS_x86_64 += x86_64/get_cpuid_test
> TEST_GEN_PROGS_x86_64 += x86_64/hyperv_cpuid
> diff --git a/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c b/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c
> new file mode 100644
> index 000000000000..12c558fc8074
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c
> @@ -0,0 +1,166 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Test that KVM_SET_BOOT_CPU_ID works as intended
> + *
> + * Copyright (C) 2020, Red Hat, Inc.
> + */
> +#define _GNU_SOURCE /* for program_invocation_name */
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/ioctl.h>
> +
> +#include "test_util.h"
> +#include "kvm_util.h"
> +#include "processor.h"
> +
> +#define N_VCPU 2
> +#define VCPU_ID0 0
> +#define VCPU_ID1 1
> +
> +static uint32_t get_bsp_flag(void)
> +{
> + return rdmsr(MSR_IA32_APICBASE) & MSR_IA32_APICBASE_BSP;
> +}
> +
> +static void guest_bsp_vcpu(void *arg)
> +{
> + GUEST_SYNC(1);
> +
> + GUEST_ASSERT(get_bsp_flag() != 0);
> +
> + GUEST_DONE();
> +}
> +
> +static void guest_not_bsp_vcpu(void *arg)
> +{
> + GUEST_SYNC(1);
> +
> + GUEST_ASSERT(get_bsp_flag() == 0);
> +
> + GUEST_DONE();
> +}
> +
> +static void test_set_boot_busy(struct kvm_vm *vm)
> +{
> + int res;
> +
> + res = _vm_ioctl(vm, KVM_SET_BOOT_CPU_ID, (void *) VCPU_ID0);
> + TEST_ASSERT(res == -1 && errno == EBUSY,
> + "KVM_SET_BOOT_CPU_ID set while running vm");
> +}
> +
> +static void run_vcpu(struct kvm_vm *vm, uint32_t vcpuid)
> +{
> + struct ucall uc;
> + int stage;
> +
> + for (stage = 0; stage < 2; stage++) {
> +
> + vcpu_run(vm, vcpuid);
> +
> + switch (get_ucall(vm, vcpuid, &uc)) {
> + case UCALL_SYNC:
> + TEST_ASSERT(!strcmp((const char *)uc.args[0], "hello") &&
> + uc.args[1] == stage + 1,
> + "Stage %d: Unexpected register values vmexit, got %lx",
> + stage + 1, (ulong)uc.args[1]);
> + test_set_boot_busy(vm);
> + break;
> + case UCALL_DONE:
> + TEST_ASSERT(stage == 1,
> + "Expected GUEST_DONE in stage 2, got stage %d",
> + stage);
> + break;
> + case UCALL_ABORT:
> + TEST_ASSERT(false, "%s at %s:%ld\n\tvalues: %#lx, %#lx",
> + (const char *)uc.args[0], __FILE__,
> + uc.args[1], uc.args[2], uc.args[3]);
> + default:
> + TEST_ASSERT(false, "Unexpected exit: %s",
> + exit_reason_str(vcpu_state(vm, vcpuid)->exit_reason));
> + }
> + }
> +}
> +
> +static struct kvm_vm *create_vm(void)
> +{
> + struct kvm_vm *vm;
> + uint64_t vcpu_pages = (DEFAULT_STACK_PGS) * 2;
^ should be N_VCPU
> + uint64_t extra_pg_pages = vcpu_pages / PTES_PER_MIN_PAGE * N_VCPU;
^
should be 2
> + uint64_t pages = DEFAULT_GUEST_PHY_PAGES + vcpu_pages + extra_pg_pages;
> +
> + pages = vm_adjust_num_guest_pages(VM_MODE_DEFAULT, pages);
> + vm = vm_create(VM_MODE_DEFAULT, pages, O_RDWR);
> +
> + kvm_vm_elf_load(vm, program_invocation_name, 0, 0);
> + vm_create_irqchip(vm);
> +
> + return vm;
> +}
> +
> +static void add_x86_vcpu(struct kvm_vm *vm, uint32_t vcpuid, bool bsp_code)
> +{
> + if (bsp_code)
> + vm_vcpu_add_default(vm, vcpuid, guest_bsp_vcpu);
> + else
> + vm_vcpu_add_default(vm, vcpuid, guest_not_bsp_vcpu);
> +
> + vcpu_set_cpuid(vm, vcpuid, kvm_get_supported_cpuid());
> +}
> +
> +static void run_vm_bsp(uint32_t bsp_vcpu)
I think the 'bsp' suffixes and prefixes make the purpose of this function
and its argument more confusing. Just
static void run_vm(uint32_t vcpu)
would be more clear to me.
> +{
> + struct kvm_vm *vm;
> + bool is_bsp_vcpu1 = bsp_vcpu == VCPU_ID1;
Could add another define
#define BSP_VCPU VCPU_ID1
And then instead of creating the above bool, just do
if (vcpu == BSP_VCPU)
> +
> + vm = create_vm();
> +
> + if (is_bsp_vcpu1)
> + vm_ioctl(vm, KVM_SET_BOOT_CPU_ID, (void *) VCPU_ID1);
Does this ioctl need to be called before creating the vcpus? The
documentation in Documentation/virt/kvm/api.rst doesn't say that.
If it can be called after creating the vcpus, then
vm_create_default_with_vcpus() can be used and there's no need
for the create_vm() and add_x86_vcpu() functions. Just use the
same guest code for both, but pass the cpu index to the guest
code function allowing something like
if (cpu == BSP_VCPU)
GUEST_ASSERT(get_bsp_flag() != 0);
else
GUEST_ASSERT(get_bsp_flag() == 0);
> +
> + add_x86_vcpu(vm, VCPU_ID0, !is_bsp_vcpu1);
> + add_x86_vcpu(vm, VCPU_ID1, is_bsp_vcpu1);
> +
> + run_vcpu(vm, VCPU_ID0);
> + run_vcpu(vm, VCPU_ID1);
> +
> + kvm_vm_free(vm);
> +}
> +
> +static void check_set_bsp_busy(void)
> +{
> + struct kvm_vm *vm;
> + int res;
> +
> + vm = create_vm();
> +
> + add_x86_vcpu(vm, VCPU_ID0, true);
> + add_x86_vcpu(vm, VCPU_ID1, false);
> +
> + res = _vm_ioctl(vm, KVM_SET_BOOT_CPU_ID, (void *) VCPU_ID1);
> + TEST_ASSERT(res == -1 && errno == EBUSY, "KVM_SET_BOOT_CPU_ID set after adding vcpu");
> +
> + run_vcpu(vm, VCPU_ID0);
> + run_vcpu(vm, VCPU_ID1);
> +
> + res = _vm_ioctl(vm, KVM_SET_BOOT_CPU_ID, (void *) VCPU_ID1);
> + TEST_ASSERT(res == -1 && errno == EBUSY, "KVM_SET_BOOT_CPU_ID set to a terminated vcpu");
> +
> + kvm_vm_free(vm);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + if (!kvm_check_cap(KVM_CAP_SET_BOOT_CPU_ID)) {
> + print_skip("set_boot_cpu_id not available");
> + return 0;
Should be exit(KSFT_SKIP);
> + }
> +
> + run_vm_bsp(VCPU_ID0);
> + run_vm_bsp(VCPU_ID1);
> + run_vm_bsp(VCPU_ID0);
> +
> + check_set_bsp_busy();
Don't you get a compiler warning here saying there's no return from a
function that returns int?
> +}
> --
> 2.29.2
>
Thanks,
drew
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