Re: [PATCH v2 18/30] KVM: s390: pci: provide routines for enabling/disabling interpretation

[Matthew Rosato]

On 1/24/22 9:36 AM, Pierre Morel wrote:
> On 1/14/22 21:31, Matthew Rosato wrote:
> > These routines will be wired into the vfio_pci_zdev ioctl handlers to
> > respond to requests to enable / disable a device for zPCI Load/Store
> > interpretation.
> >
> > The first time such a request is received, enable the necessary 
> > facilities
> > for the guest.
> >
> > Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
> > ---
> >   arch/s390/include/asm/kvm_pci.h |  4 ++
> >   arch/s390/kvm/pci.c             | 99 +++++++++++++++++++++++++++++++++
> >   arch/s390/pci/pci.c             |  3 +
> >   3 files changed, 106 insertions(+)
> >
> > diff --git a/arch/s390/include/asm/kvm_pci.h 
> > b/arch/s390/include/asm/kvm_pci.h
> > index aafee2976929..072401aa7922 100644
> > --- a/arch/s390/include/asm/kvm_pci.h
> > +++ b/arch/s390/include/asm/kvm_pci.h
> > @@ -26,4 +26,8 @@ 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);
> > +int kvm_s390_pci_interp_probe(struct zpci_dev *zdev);
> > +int kvm_s390_pci_interp_enable(struct zpci_dev *zdev);
> > +int kvm_s390_pci_interp_disable(struct zpci_dev *zdev);
> > +
> >   #endif /* ASM_KVM_PCI_H */
> > diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
> > index dae853da6df1..122d0992b521 100644
> > --- a/arch/s390/kvm/pci.c
> > +++ b/arch/s390/kvm/pci.c
> > @@ -12,7 +12,9 @@
> >   #include <asm/kvm_pci.h>
> >   #include <asm/pci.h>
> >   #include <asm/pci_insn.h>
> > +#include <asm/sclp.h>
> >   #include "pci.h"
> > +#include "kvm-s390.h"
> >   struct zpci_aift *aift;
> > @@ -143,6 +145,103 @@ int kvm_s390_pci_aen_init(u8 nisc)
> >       return rc;
> >   }
> > +int kvm_s390_pci_interp_probe(struct zpci_dev *zdev)
> > +{
> > +    /* Must have appropriate hardware facilities */
> > +    if (!(sclp.has_zpci_lsi && test_facility(69)))
>
> Should'nt we also test the other facilities we need for the 
> interpretation like ARNI, AISII, ASI and GISA ?
>
> Or are we sure they are always there when ZPCI load/store interpretation 
> is available?

I think some of these are implicit based on others but I think you're 
right that we should be testing for more than this to be safe.  I think 
additionally test for AENI, AISII, AISI -- basically we should match 
what we test for in patch 17.

> > +        return -EINVAL;
> > +
> > +    /* Must have a KVM association registered */
> > +    if (!zdev->kzdev || !zdev->kzdev->kvm)
> > +        return -EINVAL;
> > +
> > +    return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(kvm_s390_pci_interp_probe);
> > +
> > +int kvm_s390_pci_interp_enable(struct zpci_dev *zdev)
> > +{
> > +    u32 gd;
> > +    int rc;
> > +
> > +    if (!zdev->kzdev || !zdev->kzdev->kvm)
> > +        return -EINVAL;
> > +
> > +    /*
> > +     * If this is the first request to use an interpreted device, 
> > make the
> > +     * necessary vcpu changes
> > +     */
> > +    if (!zdev->kzdev->kvm->arch.use_zpci_interp)
> > +        kvm_s390_vcpu_pci_enable_interp(zdev->kzdev->kvm);
> > +
> > +    /*
> > +     * In the event of a system reset in userspace, the GISA designation
> > +     * may still be assigned because the device is still enabled.
> > +     * Verify it's the same guest before proceeding.
> > +     */
> > +    gd = (u32)(u64)&zdev->kzdev->kvm->arch.sie_page2->gisa;
>
> should use the virt_to_phys transformation ?

Yes