Re: [PATCH v5 14/21] KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding

Niklas Schnelle
2022-04-05T22:24:23Z

On Mon, 2022-04-04 at 13:43 -0400, Matthew Rosato wrote:
> These routines will be wired into a kvm ioctl in order to respond to
> requests to enable / disable a device for Adapter Event Notifications /
> Adapter Interuption Forwarding.
>
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
> arch/s390/kvm/pci.c | 247 +++++++++++++++++++++++++++++++++++++++
> arch/s390/kvm/pci.h | 1 +
> arch/s390/pci/pci_insn.c | 1 +
> 3 files changed, 249 insertions(+)
>
> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
> index 01bd8a2f503b..f0fd68569a9d 100644
> --- a/arch/s390/kvm/pci.c
> +++ b/arch/s390/kvm/pci.c
> @@ -11,6 +11,7 @@
> #include <linux/pci.h>
> #include <asm/pci.h>
> #include <asm/pci_insn.h>
> +#include <asm/pci_io.h>
> #include "pci.h"
>
> struct zpci_aift *aift;
> @@ -152,6 +153,252 @@ int kvm_s390_pci_aen_init(u8 nisc)
> return rc;
> }
>
> +/* Modify PCI: Register floating adapter interruption forwarding */
> +static int kvm_zpci_set_airq(struct zpci_dev *zdev)
> +{
> + u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_REG_INT);
> + struct zpci_fib fib = {};

Hmm this one uses '{}' as initializer while all current callers of
zpci_mod_fc() use '{0}'. As far as I know the empty braces are a GNU
extension so should work for the kernel but for consistency I'd go with
'{0}' or possibly '{.foo = bar, ...}' where that is more readable.
There too uninitialized fields will be set to 0. Unless of course there
is a conflicting KVM convention that I don't know about.

> + u8 status;
> +
> + fib.fmt0.isc = zdev->kzdev->fib.fmt0.isc;
> + fib.fmt0.sum = 1; /* enable summary notifications */
> + fib.fmt0.noi = airq_iv_end(zdev->aibv);
> + fib.fmt0.aibv = virt_to_phys(zdev->aibv->vector);
> + fib.fmt0.aibvo = 0;
> + fib.fmt0.aisb = virt_to_phys(aift->sbv->vector + (zdev->aisb / 64) * 8);
> + fib.fmt0.aisbo = zdev->aisb & 63;
> + fib.gd = zdev->gisa;
> +
> + return zpci_mod_fc(req, &fib, &status) ? -EIO : 0;
> +}
> +
> +/* Modify PCI: Unregister floating adapter interruption forwarding */
> +static int kvm_zpci_clear_airq(struct zpci_dev *zdev)
> +{
> + u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_DEREG_INT);
> + struct zpci_fib fib = {};

Same here

> + u8 cc, status;
> +
> + fib.gd = zdev->gisa;
> +
> + cc = zpci_mod_fc(req, &fib, &status);
> + if (cc == 3 || (cc == 1 && status == 24))
> + /* Function already gone or IRQs already deregistered. */
> + cc = 0;
> +
> + return cc ? -EIO : 0;
> +}
> +
>
---8<---
> int kvm_s390_pci_dev_open(struct zpci_dev *zdev)
> {
> struct kvm_zdev *kzdev;
> diff --git a/arch/s390/kvm/pci.h b/arch/s390/kvm/pci.h
> index d4997e2236ef..b4bf3d1d4b66 100644
> --- a/arch/s390/kvm/pci.h
> +++ b/arch/s390/kvm/pci.h
> @@ -20,6 +20,7 @@
> struct kvm_zdev {
> struct zpci_dev *zdev;
> struct kvm *kvm;
> + struct zpci_fib fib;
> };
>
> struct zpci_gaite {
> diff --git a/arch/s390/pci/pci_insn.c b/arch/s390/pci/pci_insn.c
> index 4c6967b73932..cd9fb186a6be 100644
> --- a/arch/s390/pci/pci_insn.c
> +++ b/arch/s390/pci/pci_insn.c
> @@ -60,6 +60,7 @@ u8 zpci_mod_fc(u64 req, struct zpci_fib *fib, u8 *status)
>
> return cc;
> }
> +EXPORT_SYMBOL_GPL(zpci_mod_fc);
>
> /* Refresh PCI Translations */
> static inline u8 __rpcit(u64 fn, u64 addr, u64 range, u8 *status)

Acked-by: Niklas Schnelle <schnelle@linux.ibm.com>