Re: [PATCH v2 2/2] KVM: LoongArch: selftests: Add FPU test case

From: Huacai Chen

Date: Tue Jun 09 2026 - 04:56:39 EST

Hi, Bibo,

On Tue, Jun 9, 2026 at 3:27 PM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
>
> Add FPU test case and verify FPU register get and set APIs, the
> FPU width supports 64/128/256 bits.
>
> Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> ---
> tools/testing/selftests/kvm/Makefile.kvm | 1 +
> .../kvm/include/loongarch/processor.h | 8 +
> .../selftests/kvm/loongarch/fpu_test.c | 145 ++++++++++++++++++
> 3 files changed, 154 insertions(+)
> create mode 100644 tools/testing/selftests/kvm/loongarch/fpu_test.c
>
> diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
> index 9118a5a51b89..7d11592b3759 100644
> --- a/tools/testing/selftests/kvm/Makefile.kvm
> +++ b/tools/testing/selftests/kvm/Makefile.kvm
> @@ -224,6 +224,7 @@ TEST_GEN_PROGS_riscv += rseq_test
> TEST_GEN_PROGS_riscv += steal_time
>
> TEST_GEN_PROGS_loongarch = loongarch/pmu_test
> +TEST_GEN_PROGS_loongarch += loongarch/fpu_test
> TEST_GEN_PROGS_loongarch += arch_timer
> TEST_GEN_PROGS_loongarch += coalesced_io_test
> TEST_GEN_PROGS_loongarch += demand_paging_test
> diff --git a/tools/testing/selftests/kvm/include/loongarch/processor.h b/tools/testing/selftests/kvm/include/loongarch/processor.h
> index 2324e311180f..981ae7078354 100644
> --- a/tools/testing/selftests/kvm/include/loongarch/processor.h
> +++ b/tools/testing/selftests/kvm/include/loongarch/processor.h
> @@ -82,6 +82,14 @@
> #define PLV_MASK 0x3
> #define LOONGARCH_CSR_PRMD 0x1
> #define LOONGARCH_CSR_EUEN 0x2
> +#define CSR_EUEN_LBTEN_SHIFT 3
> +#define CSR_EUEN_LBTEN BIT_ULL(CSR_EUEN_LBTEN_SHIFT)
> +#define CSR_EUEN_LASXEN_SHIFT 2
> +#define CSR_EUEN_LASXEN BIT_ULL(CSR_EUEN_LASXEN_SHIFT)
> +#define CSR_EUEN_LSXEN_SHIFT 1
> +#define CSR_EUEN_LSXEN BIT_ULL(CSR_EUEN_LSXEN_SHIFT)
> +#define CSR_EUEN_FPEN_SHIFT 0
> +#define CSR_EUEN_FPEN BIT_ULL(CSR_EUEN_FPEN_SHIFT)
> #define LOONGARCH_CSR_ECFG 0x4
> #define ECFGB_PMU 10
> #define ECFGF_PMU (BIT_ULL(ECFGB_PMU))
> diff --git a/tools/testing/selftests/kvm/loongarch/fpu_test.c b/tools/testing/selftests/kvm/loongarch/fpu_test.c
> new file mode 100644
> index 000000000000..5bccce9db5d0
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/loongarch/fpu_test.c
> @@ -0,0 +1,145 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <stdio.h>
> +#include <string.h>
> +#include "kvm_util.h"
> +#include "processor.h"
> +#include "loongarch/processor.h"
> +
> +struct kvm_fpureg __aligned(64) vector = {{1, 2, 3, 4 }};
> +
> +static void guest_code(void)
> +{
> + unsigned long val;
> + struct kvm_fpureg *fp = &vector;
> +
> + val = csr_read(LOONGARCH_CSR_EUEN);
> + val |= CSR_EUEN_FPEN | CSR_EUEN_LSXEN | CSR_EUEN_LASXEN;
> + csr_write(val, LOONGARCH_CSR_EUEN);
> +
> + __asm__ __volatile__("fld.d $f0, %0, 0\n" : : "r"(fp) : "$f0");
> + GUEST_SYNC(0);
> +
> + __asm__ __volatile__("vld $vr0, %0, 0\n" : : "r"(fp) : "$vr0");
> + GUEST_SYNC(1);
> +
> + __asm__ __volatile__("xvld $xr0, %0, 0\n" : : "r"(fp) : "$xr0");
> + GUEST_SYNC(2);
> +
> + __asm__ __volatile__("fst.d $f0, %0, 0\n" : : "r"(fp) : "memory");
> + GUEST_SYNC(3);
> +
> + __asm__ __volatile__("vst $vr0, %0, 0\n" : : "r"(fp) : "memory");
> + GUEST_SYNC(4);
> +
> + __asm__ __volatile__("xvst $xr0, %0, 0\n" : : "r"(fp) : "memory");
> + GUEST_SYNC(5);
> +
> + GUEST_DONE();
> +}
> +
> +static void run_vcpu(struct kvm_vcpu *vcpu)
> +{
> + struct ucall uc;
> + int cont;
> +
> + cont = 1;
> + while (cont) {
> + vcpu_run(vcpu);
> +
> + switch (get_ucall(vcpu, &uc)) {
> + case UCALL_PRINTF:
> + printf("%s", (const char *)uc.buffer);
> + break;
> + case UCALL_DONE:
> + printf("FPU test PASSED\n");
> + fallthrough;
> + case UCALL_SYNC:
> + cont = 0;
> + break;
> + case UCALL_ABORT:
> + REPORT_GUEST_ASSERT(uc);
> + default:
> + TEST_ASSERT(false, "Unexpected exit: %s",
> + exit_reason_str(vcpu->run->exit_reason));
> + }
> + }
> +}
> +
> +static bool __vm_has_feature(struct kvm_vm *vm, int feature)
> +{
> + int ret;
> +
> + ret = __kvm_has_device_attr(vm->fd, KVM_LOONGARCH_VM_FEAT_CTRL, feature);
> + return !ret;
> +}
> +
> +
> +int main(void)
> +{
> + struct kvm_vcpu *vcpu;
> + struct kvm_vm *vm;
> + struct kvm_fpu fpu;
> + struct kvm_fpureg *fp = &vector;
> +
> + vm = vm_create_with_one_vcpu(&vcpu, guest_code);
> + __TEST_REQUIRE(__vm_has_feature(vm, KVM_LOONGARCH_VM_FEAT_LSX),
> + "LSX not available, skipping test\n");
> + __TEST_REQUIRE(__vm_has_feature(vm, KVM_LOONGARCH_VM_FEAT_LASX),
> + "LASX not available, skipping test\n");
Directly use __kvm_has_device_attr() as the first patch, or use
__vm_has_feature() in the first patch?

BTW, I don't think the __ prefix is necessary.

Huacai

> +
> + run_vcpu(vcpu);
> + vcpu_fpu_get(vcpu, &fpu);
> + TEST_ASSERT(!memcmp(fpu.fpr, fp, 8), "Wanted 0x%llx from f0, got 0x%llx",
> + fp->val64[0], fpu.fpr[0].val64[0]);
> +
> + run_vcpu(vcpu);
> + vcpu_fpu_get(vcpu, &fpu);
> + TEST_ASSERT(!memcmp(fpu.fpr, fp, 16), "Wanted 0x%llx %llx from vr0, got 0x%llx %llx",
> + fp->val64[0], fp->val64[1],
> + fpu.fpr[0].val64[0], fpu.fpr[0].val64[1]);
> +
> + run_vcpu(vcpu);
> + vcpu_fpu_get(vcpu, &fpu);
> + TEST_ASSERT(!memcmp(fpu.fpr, fp, 32),
> + "Wanted 0x%llx %llx %llx %llx from xr0, got 0x%llx %llx %llx %llx",
> + fp->val64[0], fp->val64[1], fp->val64[2], fp->val64[3],
> + fpu.fpr[0].val64[0], fpu.fpr[0].val64[1],
> + fpu.fpr[0].val64[2], fpu.fpr[0].val64[3]);
> +
> + fpu.fpr[0].val64[0] += random();
> + vcpu_fpu_set(vcpu, &fpu);
> + run_vcpu(vcpu);
> + vcpu_fpu_get(vcpu, &fpu);
> + sync_global_from_guest(vm, *fp);
> + TEST_ASSERT(!memcmp(fpu.fpr, fp, 8), "Wanted 0x%llx from f0, got 0x%llx",
> + fp->val64[0], fpu.fpr[0].val64[0]);
> +
> + fpu.fpr[0].val64[0] += random();
> + fpu.fpr[0].val64[1] += random();
> + vcpu_fpu_set(vcpu, &fpu);
> + run_vcpu(vcpu);
> + vcpu_fpu_get(vcpu, &fpu);
> + sync_global_from_guest(vm, *fp);
> + TEST_ASSERT(!memcmp(fpu.fpr, fp, 16), "Wanted 0x%llx %llx from vr0, got 0x%llx %llx",
> + fp->val64[0], fp->val64[1],
> + fpu.fpr[0].val64[0], fpu.fpr[0].val64[1]);
> +
> + fpu.fpr[0].val64[0] += random();
> + fpu.fpr[0].val64[1] += random();
> + fpu.fpr[0].val64[2] += random();
> + fpu.fpr[0].val64[3] += random();
> + vcpu_fpu_set(vcpu, &fpu);
> + run_vcpu(vcpu);
> + vcpu_fpu_get(vcpu, &fpu);
> + sync_global_from_guest(vm, *fp);
> + TEST_ASSERT(!memcmp(fpu.fpr, fp, 32),
> + "Wanted 0x%llx %llx %llx %llx from xr0, got 0x%llx %llx %llx %llx",
> + fp->val64[0], fp->val64[1], fp->val64[2], fp->val64[3],
> + fpu.fpr[0].val64[0], fpu.fpr[0].val64[1],
> + fpu.fpr[0].val64[2], fpu.fpr[0].val64[3]);
> +
> + run_vcpu(vcpu);
> + kvm_vm_free(vm);
> + return 0;
> +}
> --
> 2.39.3
>