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

[Matthew Rosato <mjrosato@linux.ibm.com>]

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@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/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@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 */
>>