Re: [PATCH v3] self_tests/kvm: sync_regs test for diag318

On 07.12.20 09:16, Janosch Frank wrote:

On 12/3/20 10:52 PM, Collin Walling wrote:

...

The DIAGNOSE 0x0318 instruction, unique to s390x, is a privileged call

s/call/instruction/

...

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@linux.ibm.com

Acked-by: Janosch Frank frankja@linux.ibm.com

Some nits below.

Collin, can you have a look at the nits and resubmit soon? Then I can pick this for 5.11.

...

---

v3 changes: no longer testing the reset code, as it is handled entirely via userspace. The respective reset tests have been removed

---

tools/testing/selftests/kvm/Makefile | 2 +- .../kvm/include/s390x/diag318_test_handler.h | 13 +++ .../kvm/lib/s390x/diag318_test_handler.c | 82 +++++++++++++++++++ tools/testing/selftests/kvm/s390x/resets.c | 1 + .../selftests/kvm/s390x/sync_regs_test.c | 16 +++- 5 files changed, 112 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..1e0b766efeb7 --- /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 5

The sync_regs test has the same ID, will this be a problem?

...

+#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/resets.c b/tools/testing/selftests/kvm/s390x/resets.c index b143db6d8693..b3d7d4ac2d54 100644 --- a/tools/testing/selftests/kvm/s390x/resets.c +++ b/tools/testing/selftests/kvm/s390x/resets.c @@ -110,6 +110,7 @@ static void assert_clear(void) TEST_ASSERT(!memcmp(sync_regs->vrs, regs_null, sizeof(sync_regs->vrs)), "vrs0-15 == 0 (sync_regs)");

Whitespace damage

...

} static void assert_initial_noclear(void) 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, &regs); compare_regs(&regs, &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);