Re: [kvm-unit-tests PATCH v4 1/7] lib: s390x: Add ap library

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I made a few comments and suggestions. I am not very well-versed in the inline assembly code, so I'll leave that up to someone who is more knowledgeable. I copied @Harald since I believe it was him who wrote it.

On 2/2/24 9:59 AM, Janosch Frank wrote:
Add functions and definitions needed to test the Adjunct
Processor (AP) crypto interface.

Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
---
  lib/s390x/ap.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++
  lib/s390x/ap.h | 88 +++++++++++++++++++++++++++++++++++++++++++++
  s390x/Makefile |  1 +
  3 files changed, 186 insertions(+)
  create mode 100644 lib/s390x/ap.c
  create mode 100644 lib/s390x/ap.h

diff --git a/lib/s390x/ap.c b/lib/s390x/ap.c
new file mode 100644
index 00000000..9560ff64
--- /dev/null
+++ b/lib/s390x/ap.c
@@ -0,0 +1,97 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * AP crypto functions
+ *
+ * Some parts taken from the Linux AP driver.
+ *
+ * Copyright IBM Corp. 2024
+ * Author: Janosch Frank <frankja@xxxxxxxxxxxxx>
+ *	   Tony Krowiak <akrowia@xxxxxxxxxxxxx>
+ *	   Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
+ *	   Harald Freudenberger <freude@xxxxxxxxxx>
+ */
+
+#include <libcflat.h>
+#include <interrupt.h>
+#include <ap.h>
+#include <asm/time.h>
+#include <asm/facility.h>
+
+int ap_pqap_tapq(uint8_t ap, uint8_t qn, struct ap_queue_status *apqsw,
+		 struct pqap_r2 *r2)
+{
+	struct pqap_r0 r0 = {
+		.ap = ap,
+		.qn = qn,
+		.fc = PQAP_TEST_APQ
+	};
+	uint64_t bogus_cc = 2;
+	int cc;
+
+	/*
+	 * Test AP Queue
+	 *
+	 * Writes AP configuration information to the memory pointed
+	 * at by GR2.
+	 *
+	 * Inputs: GR0
+	 * Outputs: GR1 (APQSW), GR2 (tapq data)
+	 * Synchronous
+	 */
+	asm volatile(
+		"       tmll	%[bogus_cc],3\n"
+		"	lgr	0,%[r0]\n"
+		"	.insn	rre,0xb2af0000,0,0\n" /* PQAP */
+		"	stg	1,%[apqsw]\n"
+		"	stg	2,%[r2]\n"
+		"	ipm	%[cc]\n"
+		"	srl	%[cc],28\n"
+		: [apqsw] "=&T" (*apqsw), [r2] "=&T" (*r2), [cc] "=&d" (cc)
+		: [r0] "d" (r0), [bogus_cc] "d" (bogus_cc));
+
+	return cc;
+}
+
+int ap_pqap_qci(struct ap_config_info *info)
+{
+	struct pqap_r0 r0 = { .fc = PQAP_QUERY_AP_CONF_INFO };
+	uint64_t bogus_cc = 2;
+	int cc;
+
+	/*
+	 * Query AP Configuration Information
+	 *
+	 * Writes AP configuration information to the memory pointed
+	 * at by GR2.
+	 *
+	 * Inputs: GR0, GR2 (QCI block address)
+	 * Outputs: memory at GR2 address
+	 * Synchronous
+	 */
+	asm volatile(
+		"       tmll	%[bogus_cc],3\n"
+		"	lgr	0,%[r0]\n"
+		"	lgr	2,%[info]\n"
+		"	.insn	rre,0xb2af0000,0,0\n" /* PQAP */
+		"	ipm	%[cc]\n"
+		"	srl	%[cc],28\n"
+		: [cc] "=&d" (cc)
+		: [r0] "d" (r0), [info] "d" (info), [bogus_cc] "d" (bogus_cc)
+		: "cc", "memory", "0", "2");
+
+	return cc;
+}
+
+/* Will later be extended to a proper setup function */
+bool ap_setup(void)
+{
+	/*
+	 * Base AP support has no STFLE or SCLP feature bit but the
+	 * PQAP QCI support is indicated via stfle bit 12. As this
+	 * library relies on QCI we bail out if it's not available.
+	 */
+	if (!test_facility(12))
+		return false;


The STFLE.12 can be turned off when starting the guest, so this may not be a valid test.

We use the ap_instructions_available function (in ap.h) which executes the TAPQ command to verify whether the AP instructions are installed or not. Maybe you can do something similar here:


static inline bool ap_instructions_available(void)

{
    unsigned long reg0 = 0x0000;
    unsigned long reg1 = 0;

    asm volatile(
        "    lgr    0,%[reg0]\n"        /* qid into gr0 */
        "    lghi    1,0\n"            /* 0 into gr1 */
        "    lghi    2,0\n"            /* 0 into gr2 */
        "    .insn    rre,0xb2af0000,0,0\n"    /* PQAP(TAPQ) */
        "0:    la    %[reg1],1\n"        /* 1 into reg1 */
        "1:\n"
        EX_TABLE(0b, 1b)
        : [reg1] "+&d" (reg1)
        : [reg0] "d" (reg0)
        : "cc", "0", "1", "2");
    return reg1 != 0;
}
+
+	return true;
+}
diff --git a/lib/s390x/ap.h b/lib/s390x/ap.h
new file mode 100644
index 00000000..b806513f
--- /dev/null
+++ b/lib/s390x/ap.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * AP definitions
+ *
+ * Some parts taken from the Linux AP driver.
+ *
+ * Copyright IBM Corp. 2024
+ * Author: Janosch Frank <frankja@xxxxxxxxxxxxx>
+ *	   Tony Krowiak <akrowia@xxxxxxxxxxxxx>
+ *	   Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
+ *	   Harald Freudenberger <freude@xxxxxxxxxx>
+ */
+
+#ifndef _S390X_AP_H_
+#define _S390X_AP_H_
+
+enum PQAP_FC {
+	PQAP_TEST_APQ,
+	PQAP_RESET_APQ,
+	PQAP_ZEROIZE_APQ,
+	PQAP_QUEUE_INT_CONTRL,
+	PQAP_QUERY_AP_CONF_INFO,
+	PQAP_QUERY_AP_COMP_TYPE,
+	PQAP_BEST_AP,


Maybe use abbreviations like your function names above?

	PQAP_TAPQ,
	PQAP_RAPQ,
	PQAP_ZAPQ,
	PQAP_AQIC,
	PQAP_QCI,
	PQAP_QACT,
	PQAP_QBAP


+};
+
+struct ap_queue_status {
+	uint32_t pad0;			/* Ignored padding for zArch  */


Bit 0 is the E (queue empty) bit.


+	uint32_t empty		: 1;
+	uint32_t replies_waiting: 1;
+	uint32_t full		: 1;
+	uint32_t pad1		: 4;
+	uint32_t irq_enabled	: 1;
+	uint32_t rc		: 8;
+	uint32_t pad2		: 16;
+} __attribute__((packed))  __attribute__((aligned(8)));
+_Static_assert(sizeof(struct ap_queue_status) == sizeof(uint64_t), "APQSW size");
+
+struct ap_config_info {
+	uint8_t apsc	 : 1;	/* S bit */
+	uint8_t apxa	 : 1;	/* N bit */
+	uint8_t qact	 : 1;	/* C bit */
+	uint8_t rc8a	 : 1;	/* R bit */
+	uint8_t l	 : 1;	/* L bit */
+	uint8_t lext	 : 3;	/* Lext bits */
+	uint8_t reserved2[3];
+	uint8_t Na;		/* max # of APs - 1 */
+	uint8_t Nd;		/* max # of Domains - 1 */
+	uint8_t reserved6[10];
+	uint32_t apm[8];	/* AP ID mask */
+	uint32_t aqm[8];	/* AP (usage) queue mask */
+	uint32_t adm[8];	/* AP (control) domain mask */
+	uint8_t _reserved4[16];
+} __attribute__((aligned(8))) __attribute__ ((__packed__));
+_Static_assert(sizeof(struct ap_config_info) == 128, "PQAP QCI size");
+
+struct pqap_r0 {
+	uint32_t pad0;
+	uint8_t fc;
+	uint8_t t : 1;		/* Test facilities (TAPQ)*/
+	uint8_t pad1 : 7;
+	uint8_t ap;


This is the APID part of an APQN, so how about renaming to 'apid'


+	uint8_t qn;


This is the APQI  part of an APQN, so how about renaming to 'apqi'


+} __attribute__((packed))  __attribute__((aligned(8)));
+
+struct pqap_r2 {
+	uint8_t s : 1;		/* Special Command facility */
+	uint8_t m : 1;		/* AP4KM */
+	uint8_t c : 1;		/* AP4KC */
+	uint8_t cop : 1;	/* AP is in coprocessor mode */
+	uint8_t acc : 1;	/* AP is in accelerator mode */
+	uint8_t xcp : 1;	/* AP is in XCP-mode */
+	uint8_t n : 1;		/* AP extended addressing facility */
+	uint8_t pad_0 : 1;
+	uint8_t pad_1[3];


Is there a reason why the 'Classification'  field is left out?


+	uint8_t at;
+	uint8_t nd;
+	uint8_t pad_6;
+	uint8_t pad_7 : 4;
+	uint8_t qd : 4;
+} __attribute__((packed))  __attribute__((aligned(8)));
+_Static_assert(sizeof(struct pqap_r2) == sizeof(uint64_t), "pqap_r2 size");
+
+bool ap_setup(void);
+int ap_pqap_tapq(uint8_t ap, uint8_t qn, struct ap_queue_status *apqsw,
+		 struct pqap_r2 *r2);
+int ap_pqap_qci(struct ap_config_info *info);
+#endif
diff --git a/s390x/Makefile b/s390x/Makefile
index 7fce9f9d..4f6c627d 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -110,6 +110,7 @@ cflatobjs += lib/s390x/malloc_io.o
  cflatobjs += lib/s390x/uv.o
  cflatobjs += lib/s390x/sie.o
  cflatobjs += lib/s390x/fault.o
+cflatobjs += lib/s390x/ap.o
OBJDIRS += lib/s390x




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