On Thu, 06 Feb 2025 16:41:19 +0000,
Ganapatrao Kulkarni <gankulkarni@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> This patch adds the required changes to init vcpu in vEL2 context.
> Also adds a KVM selftest to execute guest code as a guest hypervisor(L1).
>
> Signed-off-by: Ganapatrao Kulkarni <gankulkarni@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> tools/testing/selftests/kvm/Makefile.kvm | 1 +
> .../selftests/kvm/arm64/nv_guest_hypervisor.c | 83 +++++++++++++++++++
> .../kvm/include/arm64/kvm_util_arch.h | 3 +
> .../selftests/kvm/include/arm64/nv_util.h | 28 +++++++
> .../testing/selftests/kvm/include/kvm_util.h | 1 +
> .../selftests/kvm/lib/arm64/processor.c | 59 +++++++++----
> 6 files changed, 161 insertions(+), 14 deletions(-)
> create mode 100644 tools/testing/selftests/kvm/arm64/nv_guest_hypervisor.c
> create mode 100644 tools/testing/selftests/kvm/include/arm64/nv_util.h
>
> diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
> index 4277b983cace..a85d3bec9fb1 100644
> --- a/tools/testing/selftests/kvm/Makefile.kvm
> +++ b/tools/testing/selftests/kvm/Makefile.kvm
> @@ -154,6 +154,7 @@ TEST_GEN_PROGS_arm64 += arm64/vgic_irq
> TEST_GEN_PROGS_arm64 += arm64/vgic_lpi_stress
> TEST_GEN_PROGS_arm64 += arm64/vpmu_counter_access
> TEST_GEN_PROGS_arm64 += arm64/no-vgic-v3
> +TEST_GEN_PROGS_arm64 += arm64/nv_guest_hypervisor
> TEST_GEN_PROGS_arm64 += access_tracking_perf_test
> TEST_GEN_PROGS_arm64 += arch_timer
> TEST_GEN_PROGS_arm64 += coalesced_io_test
> diff --git a/tools/testing/selftests/kvm/arm64/nv_guest_hypervisor.c b/tools/testing/selftests/kvm/arm64/nv_guest_hypervisor.c
> new file mode 100644
> index 000000000000..5aeefe43aff7
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/arm64/nv_guest_hypervisor.c
> @@ -0,0 +1,83 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2025 Ampere Computing LLC
> + */
> +#include <kvm_util.h>
> +#include <nv_util.h>
> +#include <processor.h>
> +#include <vgic.h>
> +
> +static void guest_code(void)
> +{
> + if (read_sysreg(CurrentEL) == CurrentEL_EL2)
> + GUEST_PRINTF("Executing guest code in vEL2\n");
> + else
> + GUEST_FAIL("Fail to run in vEL2\n");
> +
> + GUEST_DONE();
> +}
> +
> +static void guest_undef_handler(struct ex_regs *regs)
> +{
> + GUEST_FAIL("Unexpected exception far_el1 = 0x%lx", read_sysreg(far_el1));
> +}
> +
> +static void test_run_vcpu(struct kvm_vcpu *vcpu)
> +{
> + struct ucall uc;
> +
> + do {
> + vcpu_run(vcpu);
> +
> + switch (get_ucall(vcpu, &uc)) {
> + case UCALL_ABORT:
> + REPORT_GUEST_ASSERT(uc);
> + break;
> + case UCALL_PRINTF:
> + printf("%s", uc.buffer);
> + break;
> + case UCALL_DONE:
> + printf("Test PASS\n");
> + break;
> + default:
> + TEST_FAIL("Unknown ucall %lu", uc.cmd);
> + }
> + } while (uc.cmd != UCALL_DONE);
> +}
> +
> +static void test_nv_guest_hypervisor(void)
> +{
> + struct kvm_vcpu *vcpu;
> + struct kvm_vm *vm;
> + struct kvm_vcpu_init init;
> + int gic_fd;
> +
> + vm = vm_create(1);
> + vm_ioctl(vm, KVM_ARM_PREFERRED_TARGET, &init);
> +
> + init.features[0] = 0;
> + init_vcpu_nested(&init);
> + vcpu = aarch64_vcpu_add(vm, 0, &init, guest_code);
> +
> + __TEST_REQUIRE(is_vcpu_nested(vcpu), "Failed to Enable NV");
> +
> + vm_init_descriptor_tables(vm);
> + vcpu_init_descriptor_tables(vcpu);
> + gic_fd = vgic_v3_setup(vm, 1, 64);
> + __TEST_REQUIRE(gic_fd >= 0, "Failed to create vgic-v3");
> +
> + vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,
> + ESR_ELx_EC_UNKNOWN, guest_undef_handler);
> +
> + test_run_vcpu(vcpu);
> + kvm_vm_free(vm);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + TEST_REQUIRE(kvm_has_cap(KVM_CAP_ARM_EL2));
> +
> + test_nv_guest_hypervisor();
> +
> + return 0;
> +}
> diff --git a/tools/testing/selftests/kvm/include/arm64/kvm_util_arch.h b/tools/testing/selftests/kvm/include/arm64/kvm_util_arch.h
> index e43a57d99b56..ab5279c24413 100644
> --- a/tools/testing/selftests/kvm/include/arm64/kvm_util_arch.h
> +++ b/tools/testing/selftests/kvm/include/arm64/kvm_util_arch.h
> @@ -2,6 +2,9 @@
> #ifndef SELFTEST_KVM_UTIL_ARCH_H
> #define SELFTEST_KVM_UTIL_ARCH_H
>
> +#define CurrentEL_EL1 (1 << 2)
> +#define CurrentEL_EL2 (2 << 2)
> +
> struct kvm_vm_arch {};
>
> #endif // SELFTEST_KVM_UTIL_ARCH_H
> diff --git a/tools/testing/selftests/kvm/include/arm64/nv_util.h b/tools/testing/selftests/kvm/include/arm64/nv_util.h
> new file mode 100644
> index 000000000000..4fecf1f18554
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/arm64/nv_util.h
> @@ -0,0 +1,28 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) 2025 Ampere Computing
> + */
> +#ifndef SELFTEST_NV_UTIL_H
> +#define SELFTEST_NV_UTIL_H
> +
> +#include <linux/bitmap.h>
> +
> +/* NV helpers */
> +static inline void init_vcpu_nested(struct kvm_vcpu_init *init)
> +{
> + init->features[0] |= (1 << KVM_ARM_VCPU_HAS_EL2);
> +}
> +
> +static inline bool kvm_arm_vcpu_has_el2(struct kvm_vcpu_init *init)
> +{
> + unsigned long features = init->features[0];
> +
> + return test_bit(KVM_ARM_VCPU_HAS_EL2, &features);
> +}
> +
> +static inline bool is_vcpu_nested(struct kvm_vcpu *vcpu)
> +{
> + return vcpu->nested;
> +}
> +
> +#endif /* SELFTEST_NV_UTIL_H */
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 4c4e5a847f67..8c53dbc17f8f 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -58,6 +58,7 @@ struct kvm_vcpu {
> struct kvm_dirty_gfn *dirty_gfns;
> uint32_t fetch_index;
> uint32_t dirty_gfns_count;
> + bool nested;
> };
>
> struct userspace_mem_regions {
> diff --git a/tools/testing/selftests/kvm/lib/arm64/processor.c b/tools/testing/selftests/kvm/lib/arm64/processor.c
> index 7ba3aa3755f3..35ba2ace61a2 100644
> --- a/tools/testing/selftests/kvm/lib/arm64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/arm64/processor.c
> @@ -10,6 +10,7 @@
>
> #include "guest_modes.h"
> #include "kvm_util.h"
> +#include "nv_util.h"
> #include "processor.h"
> #include "ucall_common.h"
>
> @@ -258,14 +259,47 @@ void virt_arch_dump(FILE *stream, struct kvm_vm *vm, uint8_t indent)
> }
> }
>
> +static void aarch64_vcpu_set_reg(struct kvm_vcpu *vcpu, uint64_t sctlr_el1,
> + uint64_t tcr_el1, uint64_t ttbr0_el1)
> +{
> + uint64_t fpen;
> +
> + /*
> + * Enable FP/ASIMD to avoid trapping when accessing Q0-Q15
> + * registers, which the variable argument list macros do.
> + */
> + fpen = 3 << 20;
> +
> + if (is_vcpu_nested(vcpu)) {
> + vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_CPTR_EL2), fpen);
> + vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_SCTLR_EL2), sctlr_el1);
> + vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_TCR_EL2), tcr_el1);
> + vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_MAIR_EL2), DEFAULT_MAIR_EL1);
> + vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_TTBR0_EL2), ttbr0_el1);
> + vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_TPIDR_EL2), vcpu->id);
How about some of the basics such as HCR_EL2, MDCR_EL2? A bunch of
things there do have an impact on how the guest behaves, and relying
on defaults feels like a bad idea.
This also assumes VHE, without trying to enforce it.
Finally, how to you plan to make all the existing tests run as EL2
guests if TPIDR_EL1 isn't populated with the expected value? Surely
you need to change the read side...
M.
--
Without deviation from the norm, progress is not possible.
