linux-kernel - Re: [PATCH 13/32] KVM: s390: pci: add basic kvm

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Date:   Mon, 13 Dec 2021 16:19:45 +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 13/32] KVM: s390: pci: add basic kvm_zdev structure



On 12/7/21 21:57, 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             | 57 +++++++++++++++++++++++++++++++++
>   4 files changed, 90 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..3e491a39704c
> --- /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>
> + */
> +
> +
> +#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;
> +};
> +
> +extern int kvm_s390_pci_dev_open(struct zpci_dev *zdev);
> +extern void kvm_s390_pci_dev_release(struct zpci_dev *zdev);
> +extern int 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 86f43644756d..32810e1ed308 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..95ea865e5d29 100644
> --- a/arch/s390/kvm/Makefile
> +++ b/arch/s390/kvm/Makefile
> @@ -10,6 +10,6 @@ common-objs = $(KVM)/kvm_main.o $(KVM)/eventfd.o  $(KVM)/async_pf.o \
>   ccflags-y := -Ivirt/kvm -Iarch/s390/kvm
>   
>   kvm-objs := $(common-objs) kvm-s390.o intercept.o interrupt.o priv.o sigp.o
> -kvm-objs += diag.o gaccess.o guestdbg.o vsie.o pv.o
> +kvm-objs += diag.o gaccess.o guestdbg.o vsie.o pv.o pci.o
>   
>   obj-$(CONFIG_KVM) += kvm.o
> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
> new file mode 100644
> index 000000000000..ecfc458a5b39
> --- /dev/null
> +++ b/arch/s390/kvm/pci.c
> @@ -0,0 +1,57 @@
> +// 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;
> +
> +	if (zdev == NULL)
> +		return -ENODEV;

This check is not needed, why should this function be called with a NULL 
argument and the only caller at the moment already check it.

> +
> +	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;
> +
> +	if (!zdev || !zdev->kzdev)
> +		return;

same here

> +
> +	kzdev = zdev->kzdev;
> +	WARN_ON(kzdev->zdev != zdev);
> +	zdev->kzdev = 0;
> +	kfree(kzdev);
> +
> +}
> +EXPORT_SYMBOL_GPL(kvm_s390_pci_dev_release);
> +
> +int kvm_s390_pci_attach_kvm(struct zpci_dev *zdev, struct kvm *kvm)
> +{
> +	struct kvm_zdev *kzdev = zdev->kzdev;
> +
> +	if (!kzdev)
> +		return -ENODEV;

and here

> +
> +	kzdev->kvm = kvm;
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(kvm_s390_pci_attach_kvm);
> 

-- 
Pierre Morel
IBM Lab Boeblingen