Re: [PATCH 14/32] KVM: s390: pci: do initial setup for AEN interpretation

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On 12/9/21 2:54 PM, Christian Borntraeger wrote:
Am 07.12.21 um 21:57 schrieb Matthew Rosato:
Initial setup for Adapter Event Notification Interpretation for zPCI
passthrough devices.  Specifically, allocate a structure for forwarding of
adapter events and pass the address of this structure to firmware.

Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
---
  arch/s390/include/asm/pci_insn.h |  12 ++++
  arch/s390/kvm/interrupt.c        |  17 +++++
  arch/s390/kvm/kvm-s390.c         |   3 +
  arch/s390/kvm/pci.c              | 113 +++++++++++++++++++++++++++++++
  arch/s390/kvm/pci.h              |  42 ++++++++++++
  5 files changed, 187 insertions(+)
  create mode 100644 arch/s390/kvm/pci.h

diff --git a/arch/s390/include/asm/pci_insn.h b/arch/s390/include/asm/pci_insn.h
index 5331082fa516..e5f57cfe1d45 100644
--- a/arch/s390/include/asm/pci_insn.h
+++ b/arch/s390/include/asm/pci_insn.h
@@ -101,6 +101,7 @@ struct zpci_fib {
  /* Set Interruption Controls Operation Controls  */
  #define    SIC_IRQ_MODE_ALL        0
  #define    SIC_IRQ_MODE_SINGLE        1
+#define    SIC_SET_AENI_CONTROLS        2
  #define    SIC_IRQ_MODE_DIRECT        4
  #define    SIC_IRQ_MODE_D_ALL        16
  #define    SIC_IRQ_MODE_D_SINGLE        17
@@ -127,9 +128,20 @@ struct zpci_cdiib {
      u64 : 64;
  } __packed __aligned(8);
+/* adapter interruption parameters block */
+struct zpci_aipb {
+    u64 faisb;
+    u64 gait;
+    u16 : 13;
+    u16 afi : 3;
+    u32 : 32;
+    u16 faal;
+} __packed __aligned(8);
+
  union zpci_sic_iib {
      struct zpci_diib diib;
      struct zpci_cdiib cdiib;
+    struct zpci_aipb aipb;
  };
  DECLARE_STATIC_KEY_FALSE(have_mio);
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index f9b872e358c6..4efe0e95a40f 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -32,6 +32,7 @@
  #include "kvm-s390.h"
  #include "gaccess.h"
  #include "trace-s390.h"
+#include "pci.h"
  #define PFAULT_INIT 0x0600
  #define PFAULT_DONE 0x0680
@@ -3276,8 +3277,16 @@ static struct airq_struct gib_alert_irq = {
  void kvm_s390_gib_destroy(void)
  {
+    struct zpci_aift *aift;
+
      if (!gib)
          return;
+    aift = kvm_s390_pci_get_aift();
+    if (aift) {
+        mutex_lock(&aift->lock)

aift is a static variable and later patches seem to access that directly without the wrapper.
Can we get rid of kvm_s390_pci_get_aift?

kvm/interrupt.c must also access it when handling AEN forwarding (next patch)

;
+        kvm_s390_pci_aen_exit();
+        mutex_unlock(&aift->lock);
+    }
      chsc_sgib(0);
      unregister_adapter_interrupt(&gib_alert_irq);
      free_page((unsigned long)gib);
@@ -3315,6 +3324,14 @@ int kvm_s390_gib_init(u8 nisc)
          goto out_unreg_gal;
      }
+    if (IS_ENABLED(CONFIG_PCI) && sclp.has_aeni) {
+        if (kvm_s390_pci_aen_init(nisc)) {
+            pr_err("Initializing AEN for PCI failed\n");
+            rc = -EIO;
+            goto out_unreg_gal;
+        }
+    }
+
      KVM_EVENT(3, "gib 0x%pK (nisc=%d) initialized", gib, gib->nisc);
      goto out;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 14a18ba5ff2c..9cd3c8eb59e8 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -48,6 +48,7 @@
  #include <asm/fpu/api.h>
  #include "kvm-s390.h"
  #include "gaccess.h"
+#include "pci.h"
  #define CREATE_TRACE_POINTS
  #include "trace.h"
@@ -503,6 +504,8 @@ int kvm_arch_init(void *opaque)
          goto out;
      }
+    kvm_s390_pci_init();
+
      rc = kvm_s390_gib_init(GAL_ISC);
      if (rc)
          goto out;
diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
index ecfc458a5b39..f0e5386ff943 100644
--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -10,6 +10,113 @@
  #include <linux/kvm_host.h>
  #include <linux/pci.h>
  #include <asm/kvm_pci.h>
+#include "pci.h"
+
+static struct zpci_aift aift;

see below.
+
+static inline int __set_irq_noiib(u16 ctl, u8 isc)
+{
+    union zpci_sic_iib iib = {{0}};
+
+    return zpci_set_irq_ctrl(ctl, isc, &iib);
+}
+
+struct zpci_aift *kvm_s390_pci_get_aift(void)
+{
+    return &aift;
+}
+
+/* Caller must hold the aift lock before calling this function */
+void kvm_s390_pci_aen_exit(void)
+{
+    struct zpci_gaite *gait;
+    unsigned long flags;
+    struct airq_iv *sbv;
+    struct kvm_zdev **gait_kzdev;
+    int size;
+
+    /* Clear the GAIT and forwarding summary vector */
+    __set_irq_noiib(SIC_SET_AENI_CONTROLS, 0);
+
+    spin_lock_irqsave(&aift.gait_lock, flags);
+    gait = aift.gait;
+    sbv = aift.sbv;
+    gait_kzdev = aift.kzdev;
+    aift.gait = 0;
+    aift.sbv = 0;
+    aift.kzdev = 0;
+    spin_unlock_irqrestore(&aift.gait_lock, flags);
+
+    if (sbv)
+        airq_iv_release(sbv);
+    size = get_order(PAGE_ALIGN(ZPCI_NR_DEVICES *
+                    sizeof(struct zpci_gaite)));
+    free_pages((unsigned long)gait, size);
+    kfree(gait_kzdev);
+}
+
+int kvm_s390_pci_aen_init(u8 nisc)
+{
+    union zpci_sic_iib iib = {{0}};
+    struct page *page;
+    int rc = 0, size;
+
+    /* If already enabled for AEN, bail out now */
+    if (aift.gait || aift.sbv)
+        return -EPERM;
+
+    mutex_lock(&aift.lock);
+    aift.kzdev = kcalloc(ZPCI_NR_DEVICES, sizeof(struct kvm_zdev),
+                 GFP_KERNEL);
+    if (!aift.kzdev) {
+        rc = -ENOMEM;
+        goto unlock;
+    }
+    aift.sbv = airq_iv_create(ZPCI_NR_DEVICES, AIRQ_IV_ALLOC, 0);
+    if (!aift.sbv) {
+        rc = -ENOMEM;
+        goto free_zdev;
+    }
+    size = get_order(PAGE_ALIGN(ZPCI_NR_DEVICES *
+                    sizeof(struct zpci_gaite)));
+    page = alloc_pages(GFP_KERNEL | __GFP_ZERO, size);
+    if (!page) {
+        rc = -ENOMEM;
+        goto free_sbv;
+    }
+    aift.gait = (struct zpci_gaite *)page_to_phys(page);
+
+    iib.aipb.faisb = (u64)aift.sbv->vector;
+    iib.aipb.gait = (u64)aift.gait;
+    iib.aipb.afi = nisc;
+    iib.aipb.faal = ZPCI_NR_DEVICES;
+
+    /* Setup Adapter Event Notification Interpretation */
+    if (zpci_set_irq_ctrl(SIC_SET_AENI_CONTROLS, 0, &iib)) {
+        rc = -EIO;
+        goto free_gait;
+    }
+
+    /* Enable floating IRQs */
+    if (__set_irq_noiib(SIC_IRQ_MODE_SINGLE, nisc)) {
+        rc = -EIO;
+        kvm_s390_pci_aen_exit();
+    }
+
+    goto unlock;
+
+free_gait:
+    size = get_order(PAGE_ALIGN(ZPCI_NR_DEVICES *
+                    sizeof(struct zpci_gaite)));
+    free_pages((unsigned long)aift.gait, size);
+free_sbv:
+    airq_iv_release(aift.sbv);
+free_zdev:
+    kfree(aift.kzdev);
+unlock:
+    mutex_unlock(&aift.lock);
+    return rc;
+}
  int kvm_s390_pci_dev_open(struct zpci_dev *zdev)
  {
@@ -55,3 +162,9 @@ int kvm_s390_pci_attach_kvm(struct zpci_dev *zdev, struct kvm *kvm)
      return 0;
  }
  EXPORT_SYMBOL_GPL(kvm_s390_pci_attach_kvm);
+
+void kvm_s390_pci_init(void)
+{
+    spin_lock_init(&aift.gait_lock);
+    mutex_init(&aift.lock);
+}

Can we maybe use designated initializer for the static definition of aift, e.g. something
like
static struct zpci_aift aift = {
     .gait_lock = __SPIN_LOCK_UNLOCKED(aift.gait_lock),
     .lock    = __MUTEX_INITIALIZER(aift.lock),
}
and get rid of the init function? >

Maybe -- I can certainly do the above, but I do add a call to zpci_get_mdd() in the init function (patch 23), so if I want to in patch 23 instead add .mdd = zpci_get_mdd() to this designated initializer I'd have to re-work zpci_get_mdd (patch 12) to return the mdd rather than the CLP LIST PCI return code. We want at least a warning if we're setting a 0 for mdd because the CLP failed for some bizarre reason.

I guess one option would be to move the WARN_ON into the zpci_get_mdd() function itself and then now we can do

u32 zpci_get_mdd(void);

Niklas, what do you think?


diff --git a/arch/s390/kvm/pci.h b/arch/s390/kvm/pci.h
new file mode 100644
index 000000000000..74b06d39be3b
--- /dev/null
+++ b/arch/s390/kvm/pci.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * s390 kvm PCI passthrough support
+ *
+ * Copyright IBM Corp. 2021
+ *
+ *    Author(s): Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
+ */
+
+#ifndef __KVM_S390_PCI_H
+#define __KVM_S390_PCI_H
+
+#include <linux/pci.h>
+#include <linux/mutex.h>
+#include <asm/airq.h>
+#include <asm/kvm_pci.h>
+
+struct zpci_gaite {
+    unsigned int gisa;

since we use u8 below, what about u32
+    u8 gisc;
+    u8 count;
+    u8 reserved;
+    u8 aisbo;
+    unsigned long aisb;

and u64 ?
+};
+
+struct zpci_aift {
+    struct zpci_gaite *gait;
+    struct airq_iv *sbv;
+    struct kvm_zdev **kzdev;
+    spinlock_t gait_lock; /* Protects the gait, used during AEN forward */
+    struct mutex lock; /* Protects the other structures in aift */
+};
+
+struct zpci_aift *kvm_s390_pci_get_aift(void);
+
+int kvm_s390_pci_aen_init(u8 nisc);
+void kvm_s390_pci_aen_exit(void);
+
+void kvm_s390_pci_init(void);
+
+#endif /* __KVM_S390_PCI_H */





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