On Wed, 4 Oct 2017 15:49:37 +0200
Pierre Morel <pmo...@linux.vnet.ibm.com> wrote:
> Emulate the Adapter Interrupt Suppression in the KVM FLIC interface when
> the kernel does not support AIS.
>
> When the kernel KVM does not support AIS, we can not support VFIO PCI
> devices but we still can support emulated devices if we emulate AIS
> inside QEMU.
> Let's emulate AIS, allowing to use emulated PCI devices without KVM AIS
> support.
>
> Signed-off-by: Pierre Morel <pmo...@linux.vnet.ibm.com>
> ---
> hw/intc/s390_flic.c | 3 +-
> hw/intc/s390_flic_kvm.c | 76
> ++++++++++++++++++++++++++++++++++++++++---------
> 2 files changed, 64 insertions(+), 15 deletions(-)
>
> diff --git a/hw/intc/s390_flic.c b/hw/intc/s390_flic.c
> index 6eaf178..33a7cde 100644
> --- a/hw/intc/s390_flic.c
> +++ b/hw/intc/s390_flic.c
> @@ -185,8 +185,7 @@ static void s390_flic_common_realize(DeviceState *dev,
> Error **errp)
> " (%d > %d)", max_batch, ADAPTER_ROUTES_MAX_GSI);
> return;
> }
> -
> - fs->ais_supported = s390_has_feat(S390_FEAT_ADAPTER_INT_SUPPRESSION);
> + fs->ais_supported = false;
> }
>
> static void s390_flic_class_init(ObjectClass *oc, void *data)
> diff --git a/hw/intc/s390_flic_kvm.c b/hw/intc/s390_flic_kvm.c
> index 7ead17a..fd1aa22 100644
> --- a/hw/intc/s390_flic_kvm.c
> +++ b/hw/intc/s390_flic_kvm.c
> @@ -33,6 +33,8 @@ typedef struct KVMS390FLICState {
>
> uint32_t fd;
> bool clear_io_supported;
> + uint8_t simm;
> + uint8_t nimm;
> } KVMS390FLICState;
Instead of duplicating this, move simm/nimm into the common flic state?
>
> DeviceState *s390_flic_kvm_create(void)
> @@ -164,11 +166,24 @@ static int kvm_s390_modify_ais_mode(S390FLICState *fs,
> uint8_t isc,
> .addr = (uint64_t)&req,
> };
>
> - if (!fs->ais_supported) {
> - return -ENOSYS;
> + if (fs->ais_supported) {
> + return ioctl(flic->fd, KVM_SET_DEVICE_ATTR, &attr) ? -errno : 0;
> }
>
> - return ioctl(flic->fd, KVM_SET_DEVICE_ATTR, &attr) ? -errno : 0;
> + /* Kernel does not support AIS, emulate it here */
> + switch (mode) {
> + case SIC_IRQ_MODE_ALL:
> + flic->simm &= ~AIS_MODE_MASK(isc);
> + flic->nimm &= ~AIS_MODE_MASK(isc);
> + break;
> + case SIC_IRQ_MODE_SINGLE:
> + flic->simm |= AIS_MODE_MASK(isc);
> + flic->nimm &= ~AIS_MODE_MASK(isc);
> + break;
> + default:
> + return -EINVAL;
> + }
That's just the same as for the qemu flic. What about creating a
wrapper (to be called from css.c) in the common flic code that calls a
specific callback (only needed for kvm) and falls back to emulating if
it was not successful?
> + return 0;
> }
>
> static int kvm_s390_inject_airq(S390FLICState *fs, uint8_t type,
> @@ -180,12 +195,23 @@ static int kvm_s390_inject_airq(S390FLICState *fs,
> uint8_t type,
> .group = KVM_DEV_FLIC_AIRQ_INJECT,
> .attr = id,
> };
> + uint32_t io_int_word = (isc << 27) | IO_INT_WORD_AI;
>
> - if (!fs->ais_supported) {
> - return -ENOSYS;
> + if (fs->ais_supported) {
> + return ioctl(flic->fd, KVM_SET_DEVICE_ATTR, &attr) ? -errno : 0;
> }
>
> - return ioctl(flic->fd, KVM_SET_DEVICE_ATTR, &attr) ? -errno : 0;
> + /* Kernel does not support AIS, emulate it here */
> + if (flags && (flic->nimm & AIS_MODE_MASK(isc))) {
> + return 0;
> + }
> +
> + s390_io_interrupt(0, 0, 0, io_int_word);
> +
> + if (flags && (flic->simm & AIS_MODE_MASK(isc))) {
> + flic->nimm |= AIS_MODE_MASK(isc);
> + }
Same here: I think doing this in the generic flic would make sense.
> + return 0;
> }
>
> /**
> @@ -557,6 +583,32 @@ static void kvm_s390_flic_realize(DeviceState *dev,
> Error **errp)
> test_attr.group = KVM_DEV_FLIC_CLEAR_IO_IRQ;
> flic_state->clear_io_supported = !ioctl(flic_state->fd,
> KVM_HAS_DEVICE_ATTR, test_attr);
> + /* To support ais we need all these three FLIC attributes */
> + test_attr.group = KVM_DEV_FLIC_AISM;
> + ret = !ioctl(flic_state->fd, KVM_HAS_DEVICE_ATTR, test_attr);
> + flic_state->parent_obj.ais_supported &= ret;
> +
> + test_attr.group = KVM_DEV_FLIC_AIRQ_INJECT;
> + ret = !ioctl(flic_state->fd, KVM_HAS_DEVICE_ATTR, test_attr);
> + flic_state->parent_obj.ais_supported &= ret;
> +
> + test_attr.group = KVM_DEV_FLIC_AISM_ALL;
> + ret &= !ioctl(flic_state->fd, KVM_HAS_DEVICE_ATTR, test_attr);
> + flic_state->parent_obj.ais_supported &= ret;
> +
> + /* For buggy kernels we need to really test that the attribute is
> supported */
Ugh.
> + {
> + struct kvm_s390_ais_req req = {
> + .mode = SIC_IRQ_MODE_ALL,
> + };
> + struct kvm_device_attr attr = {
> + .group = KVM_DEV_FLIC_AISM,
> + .addr = (uint64_t)&req,
> + };
> + ret = !ioctl(flic_state->fd, KVM_SET_DEVICE_ATTR, &attr);
> + }
> + flic_state->parent_obj.ais_supported &= ret;
> +
> return;
> fail:
> error_propagate(errp, errp_local);
> @@ -578,13 +630,11 @@ static void kvm_s390_flic_reset(DeviceState *dev)
>
> flic_disable_wait_pfault(flic);
>
> - if (fs->ais_supported) {
> - for (isc = 0; isc <= MAX_ISC; isc++) {
> - rc = kvm_s390_modify_ais_mode(fs, isc, SIC_IRQ_MODE_ALL);
> - if (rc) {
> - error_report("Failed to reset ais mode for isc %d: %s",
> - isc, strerror(-rc));
> - }
> + for (isc = 0; isc <= MAX_ISC; isc++) {
> + rc = kvm_s390_modify_ais_mode(fs, isc, SIC_IRQ_MODE_ALL);
> + if (rc) {
> + error_report("Failed to reset ais mode for isc %d: %s",
> + isc, strerror(-rc));
> }
> }
>
