On 2/2/21 6:25 PM, Thomas Huth wrote:

On 29/01/2021 15.34, Pierre Morel wrote:

quoted

CSS characteristics exposes the features of the Channel SubSystem.
Let's use Store Channel Subsystem Characteristics to retrieve
the features of the CSS.

Signed-off-by: Pierre Morel <redacted>
---
  lib/s390x/css.h     | 57 +++++++++++++++++++++++++++++++++++++++++++++
  lib/s390x/css_lib.c | 50 ++++++++++++++++++++++++++++++++++++++-
  s390x/css.c         | 12 ++++++++++
  3 files changed, 118 insertions(+), 1 deletion(-)

diff --git a/lib/s390x/css.h b/lib/s390x/css.h
index 3e57445..bc0530d 100644
--- a/lib/s390x/css.h
+++ b/lib/s390x/css.h

@@ -288,4 +288,61 @@ int css_residual_count(unsigned int schid);

  void enable_io_isc(uint8_t isc);
  int wait_and_check_io_completion(int schid);
+/*
+ * CHSC definitions
+ */
+struct chsc_header {
+    u16 len;
+    u16 code;
+};
+
+/* Store Channel Subsystem Characteristics */
+struct chsc_scsc {
+    struct chsc_header req;
+    u32 reserved1;
+    u32 reserved2;
+    u32 reserved3;
+    struct chsc_header res;
+    u32 format;
+    u64 general_char[255];
+    u64 chsc_char[254];
+};
+extern struct chsc_scsc *chsc_scsc;
+
+#define CSS_GENERAL_FEAT_BITLEN    (255 * 64)
+#define CSS_CHSC_FEAT_BITLEN    (254 * 64)
+
+int get_chsc_scsc(void);
+
+static inline int _chsc(void *p)
+{
+    int cc;
+
+    asm volatile(
+        "    .insn   rre,0xb25f0000,%2,0\n"
+        "    ipm     %0\n"
+        "    srl     %0,28\n"
+        : "=d" (cc), "=m" (p)
+        : "d" (p), "m" (p)
+        : "cc");
+
+    return cc;
+}
+
+#define CHSC_SCSC    0x0010
+#define CHSC_SCSC_LEN    0x0010
+
+static inline int chsc(void *p, uint16_t code, uint16_t len)
+{
+    struct chsc_header *h = p;
+
+    h->code = code;
+    h->len = len;
+    return _chsc(p);
+}
+
+#include <bitops.h>
+#define css_general_feature(bit) test_bit_inv(bit, 
chsc_scsc->general_char)
+#define css_chsc_feature(bit) test_bit_inv(bit, chsc_scsc->chsc_char)
+
  #endif

diff --git a/lib/s390x/css_lib.c b/lib/s390x/css_lib.c
index 3c24480..fe05021 100644
--- a/lib/s390x/css_lib.c
+++ b/lib/s390x/css_lib.c

@@ -15,11 +15,59 @@

  #include <asm/arch_def.h>
  #include <asm/time.h>
  #include <asm/arch_def.h>
-
+#include <alloc_page.h>
  #include <malloc_io.h>
  #include <css.h>
  static struct schib schib;
+struct chsc_scsc *chsc_scsc;
+
+int get_chsc_scsc(void)
+{
+    int i, n;
+    int ret = 0;
+    char buffer[510];
+    char *p;
+
+    report_prefix_push("Channel Subsystem Call");
+
+    if (chsc_scsc) {
+        report_info("chsc_scsc already initialized");
+        goto end;
+    }
+
+    chsc_scsc = alloc_pages(0);
+    report_info("scsc_scsc at: %016lx", (u64)chsc_scsc);
+    if (!chsc_scsc) {
+        ret = -1;
+        report(0, "could not allocate chsc_scsc page!");
+        goto end;
+    }
+
+    ret = chsc(chsc_scsc, CHSC_SCSC, CHSC_SCSC_LEN);
+    if (ret) {
+        report(0, "chsc: CC %d", ret);
+        goto end;
+    }
+
+    for (i = 0, p = buffer; i < CSS_GENERAL_FEAT_BITLEN; i++)
+        if (css_general_feature(i)) {
+            n = snprintf(p, sizeof(buffer) - ret, "%d,", i);
+            p += n;
+        }
+    report_info("General features: %s", buffer);
+
+    for (i = 0, p = buffer, ret = 0; i < CSS_CHSC_FEAT_BITLEN; i++)
+        if (css_chsc_feature(i)) {
+            n = snprintf(p, sizeof(buffer) - ret, "%d,", i);
+            p += n;
+        }

Please use curly braces for the for-loops here, too. Rationale: Kernel 
coding style:

"Also, use braces when a loop contains more than a single simple statement"

OK, is better to read.

Thanks,
Pierre

  Thanks,
   Thomas

-- 
Pierre Morel
IBM Lab Boeblingen