Re: [PATCH v2 14/30] KVM: s390: pci: add basic kvm_zdev structure

[Matthew Rosato]

On 1/18/22 12:32 PM, Pierre Morel wrote:
> 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@xxxxxxxxxxxxx>
> > > ---
> > >   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@xxxxxxxxxxxxx>
> > > + */
> > > +
> > > +
> >
> > One blank line too much.
> >
> > Otherwise, look good to me.
> >
> > Reviewed-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
> >
> > > +#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

As discussed in other threads, I will look at changing this to
kvm-$(CONFIG_VFIO_PCI_ZDEV) += pci.o
Along with other IS_ENABLE(CONFIG_PCI) -> 
IS_ENABLED(CONFIG_VFIO_PCI_ZDDEV) changes

> > >   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@xxxxxxxxxxxxx>
> > > + */
> > > +
> > > +#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.

Yep, as mentioned in the patch 24 thread I will drop this function and 
set kzdev->kvm = kvm directly in patch 24.