On 07.12.20 16:41, Collin Walling wrote:
> The DIAGNOSE 0x0318 instruction, unique to s390x, is a privileged call
> that must be intercepted via SIE, handled in userspace, and the
> information set by the instruction is communicated back to KVM.
>
> To test the instruction interception, an ad-hoc handler is defined which
> simply has a VM execute the instruction and then userspace will extract
> the necessary info. The handler is defined such that the instruction
> invocation occurs only once. It is up to the caller to determine how the
> info returned by this handler should be used.
>
> The diag318 info is communicated from userspace to KVM via a sync_regs
> call. This is tested During a sync_regs test, where the diag318 info is
> requested via the handler, then the info is stored in the appropriate
> register in KVM via a sync registers call.
>
> If KVM does not support diag318, then the tests will print a message
> stating that diag318 was skipped, and the asserts will simply test
> against a value of 0.
>
> Signed-off-by: Collin Walling <walling@xxxxxxxxxxxxx>
Interestingly enough, this testcase actually trigger a bug:
While we gracefully handle this (no crash)
debugfs: Directory 'kvm-200206' with parent 's390dbf' already present!
is certainly not ideal....
> ---
> tools/testing/selftests/kvm/Makefile | 2 +-
> .../kvm/include/s390x/diag318_test_handler.h | 13 +++
> .../kvm/lib/s390x/diag318_test_handler.c | 82 +++++++++++++++++++
> .../selftests/kvm/s390x/sync_regs_test.c | 16 +++-
> 4 files changed, 111 insertions(+), 2 deletions(-)
> create mode 100644 tools/testing/selftests/kvm/include/s390x/diag318_test_handler.h
> create mode 100644 tools/testing/selftests/kvm/lib/s390x/diag318_test_handler.c
>
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 3d14ef77755e..426c78449044 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -36,7 +36,7 @@ endif
> LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.c lib/sparsebit.c lib/test_util.c
> LIBKVM_x86_64 = lib/x86_64/processor.c lib/x86_64/vmx.c lib/x86_64/svm.c lib/x86_64/ucall.c lib/x86_64/handlers.S
> LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c
> -LIBKVM_s390x = lib/s390x/processor.c lib/s390x/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/evmcs_test
> diff --git a/tools/testing/selftests/kvm/include/s390x/diag318_test_handler.h b/tools/testing/selftests/kvm/include/s390x/diag318_test_handler.h
> new file mode 100644
> index 000000000000..b0ed71302722
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/s390x/diag318_test_handler.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later
> + *
> + * Test handler for the s390x DIAGNOSE 0x0318 instruction.
> + *
> + * Copyright (C) 2020, IBM
> + */
> +
> +#ifndef SELFTEST_KVM_DIAG318_TEST_HANDLER
> +#define SELFTEST_KVM_DIAG318_TEST_HANDLER
> +
> +uint64_t get_diag318_info(void);
> +
> +#endif
> diff --git a/tools/testing/selftests/kvm/lib/s390x/diag318_test_handler.c b/tools/testing/selftests/kvm/lib/s390x/diag318_test_handler.c
> new file mode 100644
> index 000000000000..86b9e611ad87
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/lib/s390x/diag318_test_handler.c
> @@ -0,0 +1,82 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Test handler for the s390x DIAGNOSE 0x0318 instruction.
> + *
> + * Copyright (C) 2020, IBM
> + */
> +
> +#include "test_util.h"
> +#include "kvm_util.h"
> +
> +#define VCPU_ID 6
> +
> +#define ICPT_INSTRUCTION 0x04
> +#define IPA0_DIAG 0x8300
> +
> +static void guest_code(void)
> +{
> + uint64_t diag318_info = 0x12345678;
> +
> + asm volatile ("diag %0,0,0x318\n" : : "d" (diag318_info));
> +}
> +
> +/*
> + * The DIAGNOSE 0x0318 instruction call must be handled via userspace. As such,
> + * we create an ad-hoc VM here to handle the instruction then extract the
> + * necessary data. It is up to the caller to decide what to do with that data.
> + */
> +static uint64_t diag318_handler(void)
> +{
> + struct kvm_vm *vm;
> + struct kvm_run *run;
> + uint64_t reg;
> + uint64_t diag318_info;
> +
> + vm = vm_create_default(VCPU_ID, 0, guest_code);
> + vcpu_run(vm, VCPU_ID);
> + run = vcpu_state(vm, VCPU_ID);
> +
> + TEST_ASSERT(run->exit_reason == KVM_EXIT_S390_SIEIC,
> + "DIAGNOSE 0x0318 instruction was not intercepted");
> + TEST_ASSERT(run->s390_sieic.icptcode == ICPT_INSTRUCTION,
> + "Unexpected intercept code: 0x%x", run->s390_sieic.icptcode);
> + TEST_ASSERT((run->s390_sieic.ipa & 0xff00) == IPA0_DIAG,
> + "Unexpected IPA0 code: 0x%x", (run->s390_sieic.ipa & 0xff00));
> +
> + reg = (run->s390_sieic.ipa & 0x00f0) >> 4;
> + diag318_info = run->s.regs.gprs[reg];
> +
> + TEST_ASSERT(diag318_info != 0, "DIAGNOSE 0x0318 info not set");
> +
> + kvm_vm_free(vm);
> +
> + return diag318_info;
> +}
> +
> +uint64_t get_diag318_info(void)
> +{
> + static uint64_t diag318_info;
> + static bool printed_skip;
> +
> + /*
> + * If KVM does not support diag318, then return 0 to
> + * ensure tests do not break.
> + */
> + if (!kvm_check_cap(KVM_CAP_S390_DIAG318)) {
> + if (!printed_skip) {
> + fprintf(stdout, "KVM_CAP_S390_DIAG318 not supported. "
> + "Skipping diag318 test.\n");
> + printed_skip = true;
> + }
> + return 0;
> + }
> +
> + /*
> + * If a test has previously requested the diag318 info,
> + * then don't bother spinning up a temporary VM again.
> + */
> + if (!diag318_info)
> + diag318_info = diag318_handler();
> +
> + return diag318_info;
> +}
> diff --git a/tools/testing/selftests/kvm/s390x/sync_regs_test.c b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
> index 5731ccf34917..caf7b8859a94 100644
> --- a/tools/testing/selftests/kvm/s390x/sync_regs_test.c
> +++ b/tools/testing/selftests/kvm/s390x/sync_regs_test.c
> @@ -20,6 +20,7 @@
>
> #include "test_util.h"
> #include "kvm_util.h"
> +#include "diag318_test_handler.h"
>
> #define VCPU_ID 5
>
> @@ -70,7 +71,7 @@ static void compare_sregs(struct kvm_sregs *left, struct kvm_sync_regs *right)
>
> #undef REG_COMPARE
>
> -#define TEST_SYNC_FIELDS (KVM_SYNC_GPRS|KVM_SYNC_ACRS|KVM_SYNC_CRS)
> +#define TEST_SYNC_FIELDS (KVM_SYNC_GPRS|KVM_SYNC_ACRS|KVM_SYNC_CRS|KVM_SYNC_DIAG318)
> #define INVALID_SYNC_FIELD 0x80000000
>
> int main(int argc, char *argv[])
> @@ -152,6 +153,12 @@ int main(int argc, char *argv[])
>
> run->kvm_valid_regs = TEST_SYNC_FIELDS;
> run->kvm_dirty_regs = KVM_SYNC_GPRS | KVM_SYNC_ACRS;
> +
> + if (get_diag318_info() > 0) {
> + run->s.regs.diag318 = get_diag318_info();
> + run->kvm_dirty_regs |= KVM_SYNC_DIAG318;
> + }
> +
> rv = _vcpu_run(vm, VCPU_ID);
> TEST_ASSERT(rv == 0, "vcpu_run failed: %d\n", rv);
> TEST_ASSERT(run->exit_reason == KVM_EXIT_S390_SIEIC,
> @@ -164,6 +171,9 @@ int main(int argc, char *argv[])
> TEST_ASSERT(run->s.regs.acrs[0] == 1 << 11,
> "acr0 sync regs value incorrect 0x%x.",
> run->s.regs.acrs[0]);
> + TEST_ASSERT(run->s.regs.diag318 == get_diag318_info(),
> + "diag318 sync regs value incorrect 0x%llx.",
> + run->s.regs.diag318);
>
> vcpu_regs_get(vm, VCPU_ID, ®s);
> compare_regs(®s, &run->s.regs);
> @@ -177,6 +187,7 @@ int main(int argc, char *argv[])
> run->kvm_valid_regs = TEST_SYNC_FIELDS;
> run->kvm_dirty_regs = 0;
> run->s.regs.gprs[11] = 0xDEADBEEF;
> + run->s.regs.diag318 = 0x4B1D;
> rv = _vcpu_run(vm, VCPU_ID);
> TEST_ASSERT(rv == 0, "vcpu_run failed: %d\n", rv);
> TEST_ASSERT(run->exit_reason == KVM_EXIT_S390_SIEIC,
> @@ -186,6 +197,9 @@ int main(int argc, char *argv[])
> TEST_ASSERT(run->s.regs.gprs[11] != 0xDEADBEEF,
> "r11 sync regs value incorrect 0x%llx.",
> run->s.regs.gprs[11]);
> + TEST_ASSERT(run->s.regs.diag318 != 0x4B1D,
> + "diag318 sync regs value incorrect 0x%llx.",
> + run->s.regs.diag318);
>
> kvm_vm_free(vm);
>
