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

[Christian Borntraeger <borntraeger@linux.ibm.com>]

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@linux.ibm.com>
> ---
>   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_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?


> 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@linux.ibm.com>
> + */
> +
> +#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 */
>