Re: [kvm-unit-tests PATCH v6 1/2] s390x: topology: Check the Perform Topology Function

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On 2/8/23 12:06, Thomas Huth wrote:
On 02/02/2023 10.28, Pierre Morel wrote:
We check that the PTF instruction is working correctly when
the cpu topology facility is available.

For KVM only, we test changing of the polarity between horizontal
and vertical and that a reset set the horizontal polarity.

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
---
  s390x/Makefile      |   1 +
  s390x/topology.c    | 155 ++++++++++++++++++++++++++++++++++++++++++++
  s390x/unittests.cfg |   3 +
  3 files changed, 159 insertions(+)
  create mode 100644 s390x/topology.c

diff --git a/s390x/Makefile b/s390x/Makefile
index 52a9d82..b5fe8a3 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -39,6 +39,7 @@ tests += $(TEST_DIR)/panic-loop-extint.elf
  tests += $(TEST_DIR)/panic-loop-pgm.elf
  tests += $(TEST_DIR)/migration-sck.elf
  tests += $(TEST_DIR)/exittime.elf
+tests += $(TEST_DIR)/topology.elf
  pv-tests += $(TEST_DIR)/pv-diags.elf
diff --git a/s390x/topology.c b/s390x/topology.c
new file mode 100644
index 0000000..20f7ba2
--- /dev/null
+++ b/s390x/topology.c
@@ -0,0 +1,155 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * CPU Topology
+ *
+ * Copyright IBM Corp. 2022
+ *
+ * Authors:
+ *  Pierre Morel <pmorel@xxxxxxxxxxxxx>
+ */
+
+#include <libcflat.h>
+#include <asm/page.h>
+#include <asm/asm-offsets.h>
+#include <asm/interrupt.h>
+#include <asm/facility.h>
+#include <smp.h>
+#include <sclp.h>
+#include <s390x/hardware.h>
+
+#define PTF_REQ_HORIZONTAL    0
+#define PTF_REQ_VERTICAL    1
+#define PTF_REQ_CHECK        2
+
+#define PTF_ERR_NO_REASON    0
+#define PTF_ERR_ALRDY_POLARIZED    1
+#define PTF_ERR_IN_PROGRESS    2
+
+extern int diag308_load_reset(u64);
+
+static int ptf(unsigned long fc, unsigned long *rc)
+{
+    int cc;
+
+    asm volatile(
+        "       .insn   rre,0xb9a20000,%1,0\n"

Why are you specifying the instruction manually? I think both, GCC and Clang should know the "ptf" mnemonic, shouldn't they?

:D right !


+        "       ipm     %0\n"
+        "       srl     %0,28\n"
+        : "=d" (cc), "+d" (fc)
+        :
+        : "cc");
+
+    *rc = fc >> 8;
+    return cc;
+}
+
+static void test_ptf(void)
+{
+    unsigned long rc;
+    int cc;
+
+    /* PTF is a privilege instruction */

s/privilege/privileged/ ?

Yes, thanks


+    report_prefix_push("Privilege");
+    enter_pstate();
+    expect_pgm_int();
+    ptf(PTF_REQ_CHECK, &rc);
+    check_pgm_int_code(PGM_INT_CODE_PRIVILEGED_OPERATION);
+    report_prefix_pop();
+
+    report_prefix_push("Wrong fc");
+    expect_pgm_int();
+    ptf(0xff, &rc);
+    check_pgm_int_code(PGM_INT_CODE_SPECIFICATION);
+    report_prefix_pop();
+
+    report_prefix_push("Reserved bits");
+    expect_pgm_int();
+    ptf(0xffffffffffffff00UL, &rc);
+    check_pgm_int_code(PGM_INT_CODE_SPECIFICATION);
+    report_prefix_pop();

This function is quite big ... I'd maybe group the above checks for error conditions into a separate function instead.

OK


+    report_prefix_push("Topology Report pending");
+    /*
+     * At this moment the topology may already have changed
+     * since the VM has been started.
+     * However, we can test if a second PTF instruction
+     * reports that the topology did not change since the
+     * preceding PFT instruction.
+     */
+    ptf(PTF_REQ_CHECK, &rc);
+    cc = ptf(PTF_REQ_CHECK, &rc);
+    report(cc == 0, "PTF check should clear topology report");
+    report_prefix_pop();
+
+    report_prefix_push("Topology polarisation check");
+    /*
+     * We can not assume the state of the polarization for

s/can not/cannot/ ?

OK


Also, you sometimes write polarization with "z" and sometimes with "s". I'd suggest to standardize on "z" (as in "IBM Z" ;-))

OK


+     * any Virtual Machine but KVM.
+     * Let's skip the polarisation tests for other VMs.
+     */
+    if (!host_is_kvm()) {
+        report_skip("Topology polarisation check is done for KVM only");
+        goto end;
+    }
+
+    /*
+     * Set vertical polarization to verify that RESET sets
+     * horizontal polarization back.
+     */
+    cc = ptf(PTF_REQ_VERTICAL, &rc);
+    report(cc == 0, "Set vertical polarization.");
+
+    report(diag308_load_reset(1), "load normal reset done");
+
+    cc = ptf(PTF_REQ_CHECK, &rc);
+    report(cc == 0, "Reset should clear topology report");
+
+    cc = ptf(PTF_REQ_HORIZONTAL, &rc);
+    report(cc == 2 && rc == PTF_ERR_ALRDY_POLARIZED,
+           "After RESET polarization is horizontal");
+
+    /* Flip between vertical and horizontal polarization */
+    cc = ptf(PTF_REQ_VERTICAL, &rc);
+    report(cc == 0, "Change to vertical polarization.");
+
+    cc = ptf(PTF_REQ_CHECK, &rc);
+    report(cc == 1, "Polarization change should set topology report");
+
+    cc = ptf(PTF_REQ_HORIZONTAL, &rc);
+    report(cc == 0, "Change to horizontal polarization.");
+
+end:
+    report_prefix_pop();
+}

Apart from the nits, the patch looks fine to me.

  Thomas


Thanks,

Regards.
Pierre





--
Pierre Morel
IBM Lab Boeblingen



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