Messages in this thread | | | Subject | Re: [PATCH v6 8/9] selftests: KVM: aarch64: Introduce hypercall ABI test | From | Gavin Shan <> | Date | Wed, 27 Apr 2022 10:09:36 +0800 |
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Hi Raghavendra,
On 4/27/22 12:59 AM, Raghavendra Rao Ananta wrote: > On Tue, Apr 26, 2022 at 12:50 AM Gavin Shan <gshan@redhat.com> wrote: >> On 4/23/22 8:03 AM, Raghavendra Rao Ananta wrote: >>> Introduce a KVM selftest to check the hypercall interface >>> for arm64 platforms. The test validates the user-space' >>> [GET|SET]_ONE_REG interface to read/write the psuedo-firmware >>> registers as well as its effects on the guest upon certain >>> configurations. >>> >>> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com> >>> --- >>> tools/testing/selftests/kvm/.gitignore | 1 + >>> tools/testing/selftests/kvm/Makefile | 1 + >>> .../selftests/kvm/aarch64/hypercalls.c | 335 ++++++++++++++++++ >>> 3 files changed, 337 insertions(+) >>> create mode 100644 tools/testing/selftests/kvm/aarch64/hypercalls.c >>> >> >> There are comments about @false_hvc_info[] and some nits, as below. >> Please evaluate and improve if it makes sense to you. Otherwise, it >> looks good to me: >> >> Reviewed-by: Gavin Shan <gshan@redhat.com> >> >>> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore >>> index 1bb575dfc42e..b17e464ec661 100644 >>> --- a/tools/testing/selftests/kvm/.gitignore >>> +++ b/tools/testing/selftests/kvm/.gitignore >>> @@ -2,6 +2,7 @@ >>> /aarch64/arch_timer >>> /aarch64/debug-exceptions >>> /aarch64/get-reg-list >>> +/aarch64/hypercalls >>> /aarch64/psci_test >>> /aarch64/vcpu_width_config >>> /aarch64/vgic_init >>> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile >>> index c2cf4d318296..97eef0c03d3b 100644 >>> --- a/tools/testing/selftests/kvm/Makefile >>> +++ b/tools/testing/selftests/kvm/Makefile >>> @@ -105,6 +105,7 @@ TEST_GEN_PROGS_x86_64 += system_counter_offset_test >>> TEST_GEN_PROGS_aarch64 += aarch64/arch_timer >>> TEST_GEN_PROGS_aarch64 += aarch64/debug-exceptions >>> TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list >>> +TEST_GEN_PROGS_aarch64 += aarch64/hypercalls >>> TEST_GEN_PROGS_aarch64 += aarch64/psci_test >>> TEST_GEN_PROGS_aarch64 += aarch64/vcpu_width_config >>> TEST_GEN_PROGS_aarch64 += aarch64/vgic_init >>> diff --git a/tools/testing/selftests/kvm/aarch64/hypercalls.c b/tools/testing/selftests/kvm/aarch64/hypercalls.c >>> new file mode 100644 >>> index 000000000000..f404343a0ae3 >>> --- /dev/null >>> +++ b/tools/testing/selftests/kvm/aarch64/hypercalls.c >>> @@ -0,0 +1,335 @@ >>> +// SPDX-License-Identifier: GPL-2.0-only >>> + >>> +/* hypercalls: Check the ARM64's psuedo-firmware bitmap register interface. >>> + * >>> + * The test validates the basic hypercall functionalities that are exposed >>> + * via the psuedo-firmware bitmap register. This includes the registers' >>> + * read/write behavior before and after the VM has started, and if the >>> + * hypercalls are properly masked or unmasked to the guest when disabled or >>> + * enabled from the KVM userspace, respectively. >>> + */ >>> + >>> +#include <errno.h> >>> +#include <linux/arm-smccc.h> >>> +#include <asm/kvm.h> >>> +#include <kvm_util.h> >>> + >>> +#include "processor.h" >>> + >>> +#define FW_REG_ULIMIT_VAL(max_feat_bit) (GENMASK(max_feat_bit, 0)) >>> + >>> +/* Last valid bits of the bitmapped firmware registers */ >>> +#define KVM_REG_ARM_STD_BMAP_BIT_MAX 0 >>> +#define KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX 0 >>> +#define KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_MAX 1 >>> + >>> +struct kvm_fw_reg_info { >>> + uint64_t reg; /* Register definition */ >>> + uint64_t max_feat_bit; /* Bit that represents the upper limit of the feature-map */ >>> +}; >>> + >>> +#define FW_REG_INFO(r) \ >>> + { \ >>> + .reg = r, \ >>> + .max_feat_bit = r##_BIT_MAX, \ >>> + } >>> + >>> +static const struct kvm_fw_reg_info fw_reg_info[] = { >>> + FW_REG_INFO(KVM_REG_ARM_STD_BMAP), >>> + FW_REG_INFO(KVM_REG_ARM_STD_HYP_BMAP), >>> + FW_REG_INFO(KVM_REG_ARM_VENDOR_HYP_BMAP), >>> +}; >>> + >>> +enum test_stage { >>> + TEST_STAGE_REG_IFACE, >>> + TEST_STAGE_HVC_IFACE_FEAT_DISABLED, >>> + TEST_STAGE_HVC_IFACE_FEAT_ENABLED, >>> + TEST_STAGE_HVC_IFACE_FALSE_INFO, >>> + TEST_STAGE_END, >>> +}; >>> + >>> +static int stage = TEST_STAGE_REG_IFACE; >>> + >>> +struct test_hvc_info { >>> + uint32_t func_id; >>> + uint64_t arg1; >>> +}; >>> + >>> +#define TEST_HVC_INFO(f, a1) \ >>> + { \ >>> + .func_id = f, \ >>> + .arg1 = a1, \ >>> + } >>> + >>> +static const struct test_hvc_info hvc_info[] = { >>> + /* KVM_REG_ARM_STD_BMAP */ >>> + TEST_HVC_INFO(ARM_SMCCC_TRNG_VERSION, 0), >>> + TEST_HVC_INFO(ARM_SMCCC_TRNG_FEATURES, ARM_SMCCC_TRNG_RND64), >>> + TEST_HVC_INFO(ARM_SMCCC_TRNG_GET_UUID, 0), >>> + TEST_HVC_INFO(ARM_SMCCC_TRNG_RND32, 0), >>> + TEST_HVC_INFO(ARM_SMCCC_TRNG_RND64, 0), >>> + >>> + /* KVM_REG_ARM_STD_HYP_BMAP */ >>> + TEST_HVC_INFO(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, ARM_SMCCC_HV_PV_TIME_FEATURES), >>> + TEST_HVC_INFO(ARM_SMCCC_HV_PV_TIME_FEATURES, ARM_SMCCC_HV_PV_TIME_ST), >>> + TEST_HVC_INFO(ARM_SMCCC_HV_PV_TIME_ST, 0), >>> + >>> + /* KVM_REG_ARM_VENDOR_HYP_BMAP */ >>> + TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID, >>> + ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID), >>> + TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, 0), >>> + TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, KVM_PTP_VIRT_COUNTER), >>> +}; >>> + >>> +/* Feed false hypercall info to test the KVM behavior */ >>> +static const struct test_hvc_info false_hvc_info[] = { >>> + /* Feature support check against a different family of hypercalls */ >>> + TEST_HVC_INFO(ARM_SMCCC_TRNG_FEATURES, ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID), >>> + TEST_HVC_INFO(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, ARM_SMCCC_TRNG_RND64), >>> + TEST_HVC_INFO(ARM_SMCCC_HV_PV_TIME_FEATURES, ARM_SMCCC_TRNG_RND64), >>> +}; >>> + >> >> I don't see too much benefits of @false_hvc_info[] because >> NOT_SUPPORTED is always returned from its test case. I think >> it and its test case can be removed if you agree. I'm not >> sure if it was suggested by somebody else. >> > While this is not exactly testing the bitmap firmware registers, the > idea behind introducing false_hvc_info[] was to introduce some > negative tests and see if KVM handles it well. Especially with > *_FEATURES func_ids, we can accidentally introduce functional bugs in > KVM, and these would act as our safety net. I was planning to also > test with some reserved hypercall numbers, just to test if the kernel > doesn't panic for some reason. >
Ok, thanks for the explanation. It makes sense to me.
>>> +static void guest_test_hvc(const struct test_hvc_info *hc_info) >>> +{ >>> + unsigned int i; >>> + struct arm_smccc_res res; >>> + unsigned int hvc_info_arr_sz; >>> + >>> + hvc_info_arr_sz = >>> + hc_info == hvc_info ? ARRAY_SIZE(hvc_info) : ARRAY_SIZE(false_hvc_info); >>> + >>> + for (i = 0; i < hvc_info_arr_sz; i++, hc_info++) { >>> + memset(&res, 0, sizeof(res)); >>> + smccc_hvc(hc_info->func_id, hc_info->arg1, 0, 0, 0, 0, 0, 0, &res); >>> + >>> + switch (stage) { >>> + case TEST_STAGE_HVC_IFACE_FEAT_DISABLED: >>> + case TEST_STAGE_HVC_IFACE_FALSE_INFO: >>> + GUEST_ASSERT_3(res.a0 == SMCCC_RET_NOT_SUPPORTED, >>> + res.a0, hc_info->func_id, hc_info->arg1); >>> + break; >>> + case TEST_STAGE_HVC_IFACE_FEAT_ENABLED: >>> + GUEST_ASSERT_3(res.a0 != SMCCC_RET_NOT_SUPPORTED, >>> + res.a0, hc_info->func_id, hc_info->arg1); >>> + break; >>> + default: >>> + GUEST_ASSERT_1(0, stage); >>> + } >>> + } >>> +} >>> + >>> +static void guest_code(void) >>> +{ >>> + while (stage != TEST_STAGE_END) { >>> + switch (stage) { >>> + case TEST_STAGE_REG_IFACE: >>> + break; >>> + case TEST_STAGE_HVC_IFACE_FEAT_DISABLED: >>> + case TEST_STAGE_HVC_IFACE_FEAT_ENABLED: >>> + guest_test_hvc(hvc_info); >>> + break; >>> + case TEST_STAGE_HVC_IFACE_FALSE_INFO: >>> + guest_test_hvc(false_hvc_info); >>> + break; >>> + default: >>> + GUEST_ASSERT_1(0, stage); >>> + } >>> + >>> + GUEST_SYNC(stage); >>> + } >>> + >>> + GUEST_DONE(); >>> +} >>> + >>> +static int set_fw_reg(struct kvm_vm *vm, uint64_t id, uint64_t val) >>> +{ >>> + struct kvm_one_reg reg = { >>> + .id = id, >>> + .addr = (uint64_t)&val, >>> + }; >>> + >>> + return _vcpu_ioctl(vm, 0, KVM_SET_ONE_REG, ®); >>> +} >>> + >>> +static void get_fw_reg(struct kvm_vm *vm, uint64_t id, uint64_t *addr) >>> +{ >>> + struct kvm_one_reg reg = { >>> + .id = id, >>> + .addr = (uint64_t)addr, >>> + }; >>> + >>> + vcpu_ioctl(vm, 0, KVM_GET_ONE_REG, ®); >>> +} >>> + >>> +struct st_time { >>> + uint32_t rev; >>> + uint32_t attr; >>> + uint64_t st_time; >>> +}; >>> + >>> +#define STEAL_TIME_SIZE ((sizeof(struct st_time) + 63) & ~63) >>> +#define ST_GPA_BASE (1 << 30) >>> + >>> +static void steal_time_init(struct kvm_vm *vm) >>> +{ >>> + uint64_t st_ipa = (ulong)ST_GPA_BASE; >>> + unsigned int gpages; >>> + struct kvm_device_attr dev = { >>> + .group = KVM_ARM_VCPU_PVTIME_CTRL, >>> + .attr = KVM_ARM_VCPU_PVTIME_IPA, >>> + .addr = (uint64_t)&st_ipa, >>> + }; >>> + >>> + gpages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, STEAL_TIME_SIZE); >>> + vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, gpages, 0); >>> + >>> + vcpu_ioctl(vm, 0, KVM_SET_DEVICE_ATTR, &dev); >>> +} >>> + >>> +static void test_fw_regs_before_vm_start(struct kvm_vm *vm) >>> +{ >>> + uint64_t val; >>> + unsigned int i; >>> + int ret; >>> + >>> + for (i = 0; i < ARRAY_SIZE(fw_reg_info); i++) { >>> + const struct kvm_fw_reg_info *reg_info = &fw_reg_info[i]; >>> + >>> + /* First 'read' should be an upper limit of the features supported */ >>> + get_fw_reg(vm, reg_info->reg, &val); >>> + TEST_ASSERT(val == FW_REG_ULIMIT_VAL(reg_info->max_feat_bit), >>> + "Expected all the features to be set for reg: 0x%lx; expected: 0x%lx; read: 0x%lx\n", >>> + reg_info->reg, FW_REG_ULIMIT_VAL(reg_info->max_feat_bit), val); >>> + >>> + /* Test a 'write' by disabling all the features of the register map */ >>> + ret = set_fw_reg(vm, reg_info->reg, 0); >>> + TEST_ASSERT(ret == 0, >>> + "Failed to clear all the features of reg: 0x%lx; ret: %d\n", >>> + reg_info->reg, errno); >>> + >>> + get_fw_reg(vm, reg_info->reg, &val); >>> + TEST_ASSERT(val == 0, >>> + "Expected all the features to be cleared for reg: 0x%lx\n", reg_info->reg); >>> + >>> + /* >>> + * Test enabling a feature that's not supported. >>> + * Avoid this check if all the bits are occupied. >>> + */ >>> + if (reg_info->max_feat_bit < 63) { >>> + ret = set_fw_reg(vm, reg_info->reg, BIT(reg_info->max_feat_bit + 1)); >>> + TEST_ASSERT(ret != 0 && errno == EINVAL, >>> + "Unexpected behavior or return value (%d) while setting an unsupported feature for reg: 0x%lx\n", >>> + errno, reg_info->reg); >>> + } >>> + } >>> +} >> >> Just in case :) >> >> ret = set_fw_reg(vm, reg_info->reg, GENMASK(63, reg_info->max_feat_bit + 1)); >> > It may be better to cover the entire range, but to test only the > (max_feat_bit + 1) gives us the advantage of checking if there's any > discrepancy between the kernel and the test, now that *_BIT_MAX are > not a part of UAPI headers. > > Probably also include your test along with the existing one?
Thanks for your explanation again. Lets keep it as it is then.
>> >>> + >>> +static void test_fw_regs_after_vm_start(struct kvm_vm *vm) >>> +{ >>> + uint64_t val; >>> + unsigned int i; >>> + int ret; >>> + >>> + for (i = 0; i < ARRAY_SIZE(fw_reg_info); i++) { >>> + const struct kvm_fw_reg_info *reg_info = &fw_reg_info[i]; >>> + >>> + /* >>> + * Before starting the VM, the test clears all the bits. >>> + * Check if that's still the case. >>> + */ >>> + get_fw_reg(vm, reg_info->reg, &val); >>> + TEST_ASSERT(val == 0, >>> + "Expected all the features to be cleared for reg: 0x%lx\n", >>> + reg_info->reg); >>> + >>> + /* >>> + * Set all the features for this register again. KVM shouldn't >>> + * allow this as the VM is running. >>> + */ >>> + ret = set_fw_reg(vm, reg_info->reg, FW_REG_ULIMIT_VAL(reg_info->max_feat_bit)); >>> + TEST_ASSERT(ret != 0 && errno == EBUSY, >>> + "Unexpected behavior or return value (%d) while setting a feature while VM is running for reg: 0x%lx\n", >>> + errno, reg_info->reg); >>> + } >>> +} >>> + >> >> I guess you want to check -EBUSY is returned. In that case, >> the comments here could be clearer, something like below >> to emphasize '-EBUSY'. >> >> /* >> * After VM runs for once, -EBUSY should be returned on attempt >> * to set features. Check if the correct errno is returned. >> */ >> > Sounds good. > >>> +static struct kvm_vm *test_vm_create(void) >>> +{ >>> + struct kvm_vm *vm; >>> + >>> + vm = vm_create_default(0, 0, guest_code); >>> + >>> + ucall_init(vm, NULL); >>> + steal_time_init(vm); >>> + >>> + return vm; >>> +} >>> + >>> +static struct kvm_vm *test_guest_stage(struct kvm_vm *vm) >>> +{ >>> + struct kvm_vm *ret_vm = vm; >>> + >>> + pr_debug("Stage: %d\n", stage); >>> + >>> + switch (stage) { >>> + case TEST_STAGE_REG_IFACE: >>> + test_fw_regs_after_vm_start(vm); >>> + break; >>> + case TEST_STAGE_HVC_IFACE_FEAT_DISABLED: >>> + /* Start a new VM so that all the features are now enabled by default */ >>> + kvm_vm_free(vm); >>> + ret_vm = test_vm_create(); >>> + break; >>> + case TEST_STAGE_HVC_IFACE_FEAT_ENABLED: >>> + case TEST_STAGE_HVC_IFACE_FALSE_INFO: >>> + break; >>> + default: >>> + TEST_FAIL("Unknown test stage: %d\n", stage); >>> + } >>> + >>> + stage++; >>> + sync_global_to_guest(vm, stage); >>> + >>> + return ret_vm; >>> +} >>> + >>> +static void test_run(void) >>> +{ >>> + struct kvm_vm *vm; >>> + struct ucall uc; >>> + bool guest_done = false; >>> + >>> + vm = test_vm_create(); >>> + >>> + test_fw_regs_before_vm_start(vm); >>> + >>> + while (!guest_done) { >>> + vcpu_run(vm, 0); >>> + >>> + switch (get_ucall(vm, 0, &uc)) { >>> + case UCALL_SYNC: >>> + vm = test_guest_stage(vm); >>> + break; >>> + case UCALL_DONE: >>> + guest_done = true; >>> + break; >>> + case UCALL_ABORT: >>> + TEST_FAIL("%s at %s:%ld\n\tvalues: 0x%lx, 0x%lx; 0x%lx, stage: %u", >>> + (const char *)uc.args[0], __FILE__, uc.args[1], >>> + uc.args[2], uc.args[3], uc.args[4], stage); >>> + break; >>> + default: >>> + TEST_FAIL("Unexpected guest exit\n"); >>> + } >>> + } >>> + >>> + kvm_vm_free(vm); >>> +} >>> + >>> +int main(void) >>> +{ >>> + setbuf(stdout, NULL); >>> + >>> + test_run(); >>> + return 0; >>> +} >>>
[...]
Thanks, Gavin
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