linux-kernel - Re: [PATCH v2 14/30] KVM: s390: pci: add basic kvm

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Date:   Tue, 18 Jan 2022 18:32:02 +0100
From:   Pierre Morel <pmorel@...ux.ibm.com>
To:     Matthew Rosato <mjrosato@...ux.ibm.com>, linux-s390@...r.kernel.org
Cc:     alex.williamson@...hat.com, cohuck@...hat.com,
        schnelle@...ux.ibm.com, farman@...ux.ibm.com,
        borntraeger@...ux.ibm.com, hca@...ux.ibm.com, gor@...ux.ibm.com,
        gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
        frankja@...ux.ibm.com, david@...hat.com, imbrenda@...ux.ibm.com,
        vneethv@...ux.ibm.com, oberpar@...ux.ibm.com, freude@...ux.ibm.com,
        thuth@...hat.com, pasic@...ux.ibm.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 14/30] KVM: s390: pci: add basic kvm_zdev structure



On 1/17/22 17:25, Pierre Morel wrote:
> 
> 
> On 1/14/22 21:31, Matthew Rosato wrote:
>> This structure will be used to carry kvm passthrough information 
>> related to
>> zPCI devices.
>>
>> Signed-off-by: Matthew Rosato <mjrosato@...ux.ibm.com>
>> ---
>>   arch/s390/include/asm/kvm_pci.h | 29 +++++++++++++++++++++
>>   arch/s390/include/asm/pci.h     |  3 +++
>>   arch/s390/kvm/Makefile          |  2 +-
>>   arch/s390/kvm/pci.c             | 46 +++++++++++++++++++++++++++++++++
>>   4 files changed, 79 insertions(+), 1 deletion(-)
>>   create mode 100644 arch/s390/include/asm/kvm_pci.h
>>   create mode 100644 arch/s390/kvm/pci.c
>>
>> diff --git a/arch/s390/include/asm/kvm_pci.h 
>> b/arch/s390/include/asm/kvm_pci.h
>> new file mode 100644
>> index 000000000000..aafee2976929
>> --- /dev/null
>> +++ b/arch/s390/include/asm/kvm_pci.h
>> @@ -0,0 +1,29 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * KVM PCI Passthrough for virtual machines on s390
>> + *
>> + * Copyright IBM Corp. 2021
>> + *
>> + *    Author(s): Matthew Rosato <mjrosato@...ux.ibm.com>
>> + */
>> +
>> +
> 
> One blank line too much.
> 
> Otherwise, look good to me.
> 
> Reviewed-by: Pierre Morel <pmorel@...ux.ibm.com>
> 
>> +#ifndef ASM_KVM_PCI_H
>> +#define ASM_KVM_PCI_H
>> +
>> +#include <linux/types.h>
>> +#include <linux/kvm_types.h>
>> +#include <linux/kvm_host.h>
>> +#include <linux/kvm.h>
>> +#include <linux/pci.h>
>> +
>> +struct kvm_zdev {
>> +    struct zpci_dev *zdev;
>> +    struct kvm *kvm;
>> +};
>> +
>> +int kvm_s390_pci_dev_open(struct zpci_dev *zdev);
>> +void kvm_s390_pci_dev_release(struct zpci_dev *zdev);
>> +void kvm_s390_pci_attach_kvm(struct zpci_dev *zdev, struct kvm *kvm);
>> +
>> +#endif /* ASM_KVM_PCI_H */
>> diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
>> index f3cd2da8128c..9b6c657d8d31 100644
>> --- a/arch/s390/include/asm/pci.h
>> +++ b/arch/s390/include/asm/pci.h
>> @@ -97,6 +97,7 @@ struct zpci_bar_struct {
>>   };
>>   struct s390_domain;
>> +struct kvm_zdev;
>>   #define ZPCI_FUNCTIONS_PER_BUS 256
>>   struct zpci_bus {
>> @@ -190,6 +191,8 @@ struct zpci_dev {
>>       struct dentry    *debugfs_dev;
>>       struct s390_domain *s390_domain; /* s390 IOMMU domain data */
>> +
>> +    struct kvm_zdev *kzdev; /* passthrough data */
>>   };
>>   static inline bool zdev_enabled(struct zpci_dev *zdev)
>> diff --git a/arch/s390/kvm/Makefile b/arch/s390/kvm/Makefile
>> index b3aaadc60ead..a26f4fe7b680 100644
>> --- a/arch/s390/kvm/Makefile
>> +++ b/arch/s390/kvm/Makefile
>> @@ -11,5 +11,5 @@ ccflags-y := -Ivirt/kvm -Iarch/s390/kvm
>>   kvm-objs := $(common-objs) kvm-s390.o intercept.o interrupt.o priv.o 
>> sigp.o
>>   kvm-objs += diag.o gaccess.o guestdbg.o vsie.o pv.o
>> -
>> +kvm-$(CONFIG_PCI) += pci.o
>>   obj-$(CONFIG_KVM) += kvm.o
>> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
>> new file mode 100644
>> index 000000000000..1c33bc7bf2bd
>> --- /dev/null
>> +++ b/arch/s390/kvm/pci.c
>> @@ -0,0 +1,46 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * s390 kvm PCI passthrough support
>> + *
>> + * Copyright IBM Corp. 2021
>> + *
>> + *    Author(s): Matthew Rosato <mjrosato@...ux.ibm.com>
>> + */
>> +
>> +#include <linux/kvm_host.h>
>> +#include <linux/pci.h>
>> +#include <asm/kvm_pci.h>
>> +
>> +int kvm_s390_pci_dev_open(struct zpci_dev *zdev)
>> +{
>> +    struct kvm_zdev *kzdev;
>> +
>> +    kzdev = kzalloc(sizeof(struct kvm_zdev), GFP_KERNEL);
>> +    if (!kzdev)
>> +        return -ENOMEM;
>> +
>> +    kzdev->zdev = zdev;
>> +    zdev->kzdev = kzdev;
>> +
>> +    return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(kvm_s390_pci_dev_open);
>> +
>> +void kvm_s390_pci_dev_release(struct zpci_dev *zdev)
>> +{
>> +    struct kvm_zdev *kzdev;
>> +
>> +    kzdev = zdev->kzdev;
>> +    WARN_ON(kzdev->zdev != zdev);
>> +    zdev->kzdev = 0;
>> +    kfree(kzdev);
>> +}
>> +EXPORT_SYMBOL_GPL(kvm_s390_pci_dev_release);
>> +
>> +void kvm_s390_pci_attach_kvm(struct zpci_dev *zdev, struct kvm *kvm)
>> +{
>> +    struct kvm_zdev *kzdev = zdev->kzdev;
>> +
>> +    kzdev->kvm = kvm;
>> +}
>> +EXPORT_SYMBOL_GPL(kvm_s390_pci_attach_kvm);
>>
> 

Working now on patch 24, I am not sure that this function is necessary.
the only purpose seems to set kzdev->kvm = kvm while we already know 
kzdev in the caller.



-- 
Pierre Morel
IBM Lab Boeblingen