Re: [PATCH v2 15/30] KVM: s390: pci: do initial setup for AEN interpretation

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On 1/14/22 21:31, Matthew Rosato wrote:
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.h      |   4 +
  arch/s390/include/asm/pci_insn.h |  12 +++
  arch/s390/kvm/interrupt.c        |  14 +++
  arch/s390/kvm/kvm-s390.c         |   9 ++
  arch/s390/kvm/pci.c              | 144 +++++++++++++++++++++++++++++++
  arch/s390/kvm/pci.h              |  42 +++++++++
  arch/s390/pci/pci.c              |   6 ++
  7 files changed, 231 insertions(+)
  create mode 100644 arch/s390/kvm/pci.h

diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
index 9b6c657d8d31..9ff8dc19975e 100644
--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -9,6 +9,7 @@
  #include <asm-generic/pci.h>
  #include <asm/pci_clp.h>
  #include <asm/pci_debug.h>
+#include <asm/pci_insn.h>
  #include <asm/sclp.h>
#define PCIBIOS_MIN_IO 0x1000
@@ -204,6 +205,9 @@ extern const struct attribute_group *zpci_attr_groups[];
  extern unsigned int s390_pci_force_floating __initdata;
  extern unsigned int s390_pci_no_rid;
+extern union zpci_sic_iib *zpci_aipb;
+extern struct airq_iv *zpci_aif_sbv;
+
  /* -----------------------------------------------------------------------------
    Prototypes
  ----------------------------------------------------------------------------- */
diff --git a/arch/s390/include/asm/pci_insn.h b/arch/s390/include/asm/pci_insn.h
index 32759c407b8f..ad9000295c82 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..a591b8cd662f 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
@@ -3278,6 +3279,11 @@ void kvm_s390_gib_destroy(void)
  {
  	if (!gib)
  		return;
+	if (IS_ENABLED(CONFIG_PCI) && sclp.has_aeni && aift) {
+		mutex_lock(&aift->lock);
+		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 +3321,14 @@ 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..01dc3f6883d0 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 +504,14 @@ int kvm_arch_init(void *opaque)
  		goto out;
  	}
+ if (IS_ENABLED(CONFIG_PCI)) {
+		rc = kvm_s390_pci_init();
+		if (rc) {
+			pr_err("Unable to allocate AIFT for PCI\n");
+			goto out;
+		}
+	}
+
  	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 1c33bc7bf2bd..dae853da6df1 100644
--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -10,6 +10,138 @@
  #include <linux/kvm_host.h>
  #include <linux/pci.h>
  #include <asm/kvm_pci.h>
+#include <asm/pci.h>
+#include <asm/pci_insn.h>
+#include "pci.h"
+
+struct zpci_aift *aift;
+
+static inline int __set_irq_noiib(u16 ctl, u8 isc)
+{
+	union zpci_sic_iib iib = {{0}};
+
+	return zpci_set_irq_ctrl(ctl, isc, &iib);
+}
+
+/* Caller must hold the aift lock before calling this function */
+void kvm_s390_pci_aen_exit(void)
+{
+	unsigned long flags;
+	struct kvm_zdev **gait_kzdev;
+
+	/*
+	 * Contents of the aipb remain registered for the life of the host
+	 * kernel, the information preserved in zpci_aipb and zpci_aif_sbv
+	 * in case we insert the KVM module again later.  Clear the AIFT
+	 * information and free anything not registered with underlying
+	 * firmware.
+	 */
+	spin_lock_irqsave(&aift->gait_lock, flags);
+	gait_kzdev = aift->kzdev;
+	aift->gait = 0;
+	aift->sbv = 0;
+	aift->kzdev = 0;
+	spin_unlock_irqrestore(&aift->gait_lock, flags);
+
+	kfree(gait_kzdev);
+}
+
+int kvm_s390_pci_aen_init(u8 nisc)
+{
+	struct page *page;
+	int rc = 0, size;
+	bool first = false;
+
+	/* 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;
+	}
+
+	if (!zpci_aipb) {

I think you should externalize all this allocation and setup of aipb
in a dedicated function zpci_setup_aipb()
from here ----->

+		zpci_aipb = kzalloc(sizeof(union zpci_sic_iib), GFP_KERNEL);
+		if (!zpci_aipb) {
+			rc = -ENOMEM;
+			goto free_zdev;
+		}
+		first = true;
+		aift->sbv = airq_iv_create(ZPCI_NR_DEVICES, AIRQ_IV_ALLOC, 0);
+		if (!aift->sbv) {
+			rc = -ENOMEM;
+			goto free_aipb;
+		}
+		zpci_aif_sbv = aift->sbv;
+		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);
+
+		zpci_aipb->aipb.faisb = virt_to_phys(aift->sbv->vector);
+		zpci_aipb->aipb.gait = virt_to_phys(aift->gait);
+		zpci_aipb->aipb.afi = nisc;
+		zpci_aipb->aipb.faal = ZPCI_NR_DEVICES;
+
+		/* Setup Adapter Event Notification Interpretation */
+		if (zpci_set_irq_ctrl(SIC_SET_AENI_CONTROLS, 0, zpci_aipb)) {
+			rc = -EIO;
+			goto free_gait;

to here---->

+		}
+	} else {
+		/*
+		 * AEN registration can only happen once per system boot.  If
+		 * an aipb already exists then AEN was already registered and
+		 * we can re-use the aipb contents.  This can only happen if
+		 * the KVM module was removed and re-inserted.
+		 */
+		if (zpci_aipb->aipb.afi != nisc ||
+		    zpci_aipb->aipb.faal != ZPCI_NR_DEVICES) {
+			rc = -EINVAL;
+			goto free_zdev;
+		}
+		aift->sbv = zpci_aif_sbv;
+		aift->gait = (struct zpci_gaite *)zpci_aipb->aipb.gait;
+	}
+
+	/* Enable floating IRQs */
+	if (__set_irq_noiib(SIC_IRQ_MODE_SINGLE, nisc)) {
+		rc = -EIO;
+		kvm_s390_pci_aen_exit();
+	}
+
+	goto unlock;

and the according errors

here ---->
+
+free_gait:
+	size = get_order(PAGE_ALIGN(ZPCI_NR_DEVICES *
+				    sizeof(struct zpci_gaite)));
+	free_pages((unsigned long)aift->gait, size);
+free_sbv:
+	if (first) {
+		/* If AEN setup failed, only free a newly-allocated sbv */
+		airq_iv_release(aift->sbv);
+		zpci_aif_sbv = 0;
+	}
+free_aipb:
+	if (first) {
+		/* If AEN setup failed, only free a newly-allocated aipb */
+		kfree(zpci_aipb);
+		zpci_aipb = 0;
+	}

to here ---->

To simplify the understanding.

+free_zdev:
+	kfree(aift->kzdev);
+unlock:
+	mutex_unlock(&aift->lock);
+	return rc;
+}

... snip...

The second part of the if(aipb) else
could also be externalise in zpci_reset_aipb()

which leads to

   if(!aipb)
	ret = zpci_setup_aipb()
   else
	ret = zpci_reset_aipb()

   if (ret)
	goto cleanup;

    enable_irq()
	goto unlock;

I think that if we can do that it would be much clearer.
what do you think?

--
Pierre Morel
IBM Lab Boeblingen



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