Re: [PATCH v4 0/9] KVM: arm64: Initial host support for the Apple M1

Hi Marc,

On 6/1/21 11:39 AM, Marc Zyngier wrote:

This is a new version of the series previously posted at [3], reworking
the vGIC and timer code to cope with the M1 braindead^Wamusing nature.

Hardly any change this time around, mostly rebased on top of upstream
now that the dependencies have made it in.

Tested with multiple concurrent VMs running from an initramfs.

Until someone shouts loudly now, I'll take this into 5.14 (and in
-next from tomorrow).

I am not familiar with irqdomains or with the irqchip infrastructure, so I can't
really comment on patch #8.

I tried testing this with a GICv3 by modifying the driver to set
no_hw_deactivation and no_maint_irq_mask:

diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index 340c51d87677..d0c6f808d7f4 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c

@@ -565,8 +565,10 @@ int kvm_vgic_hyp_init(void)

        if (ret)
                return ret;
 
+       /*
        if (!has_mask)
                return 0;
+               */
 
        ret = request_percpu_irq(kvm_vgic_global_state.maint_irq,
                                 vgic_maintenance_handler,

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 453fc425eede..9ce4dee20655 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c

@@ -1850,6 +1850,12 @@ static void __init gic_of_setup_kvm_info(struct device_node

*node)
        if (!ret)
                gic_v3_kvm_info.vcpu = r;
 
+       gic_v3_kvm_info.no_hw_deactivation = true;
+       gic_v3_kvm_info.no_maint_irq_mask = true;
+
+       vgic_set_kvm_info(&gic_v3_kvm_info);
+       return;
+
        gic_v3_kvm_info.has_v4 = gic_data.rdists.has_vlpis;
        gic_v3_kvm_info.has_v4_1 = gic_data.rdists.has_rvpeid;
        vgic_set_kvm_info(&gic_v3_kvm_info);

Kept the maintenance irq ID so the IRQ gets enabled at the Redistributor level. I
don't know if I managed to break something with those changes, but when testing on
the model and on a rockpro64 (with the patches cherry-picked on top of v5.13-rc7)
I kept seeing rcu stalls. I assume I did something wrong.

Thanks,

Alex

* From v3 [3]:
  - Rebased on 5.13-rc4 to match the kvmarm/next base
  - Moved stuff from patch #7 to its logical spot in patch #8
  - Changed the include/linux/irqchip/arm-vgic-info.h guard
  - Collected RBs from Alex, with thanks

* From v2 [2]:
  - Rebased on 5.13-rc1
  - Fixed a couple of nits in the GIC registration code

* From v1 [1]:
  - Rebased on Hector's v4 posting[0]
  - Dropped a couple of patches that have been merged in the above series
  - Fixed irq_ack callback on the timer path

[0] https://lore.kernel.org/r/20210402090542.131194-1-marcan@marcan.st (local)
[1] https://lore.kernel.org/r/20210316174617.173033-1-maz@kernel.org (local)
[2] https://lore.kernel.org/r/20210403112931.1043452-1-maz@kernel.org (local)
[3] https://lore.kernel.org/r/20210510134824.1910399-1-maz@kernel.org (local)

Marc Zyngier (9):
  irqchip/gic: Split vGIC probing information from the GIC code
  KVM: arm64: Handle physical FIQ as an IRQ while running a guest
  KVM: arm64: vgic: Be tolerant to the lack of maintenance interrupt
    masking
  KVM: arm64: vgic: Let an interrupt controller advertise lack of HW
    deactivation
  KVM: arm64: vgic: move irq->get_input_level into an ops structure
  KVM: arm64: vgic: Implement SW-driven deactivation
  KVM: arm64: timer: Refactor IRQ configuration
  KVM: arm64: timer: Add support for SW-based deactivation
  irqchip/apple-aic: Advertise some level of vGICv3 compatibility

 arch/arm64/kvm/arch_timer.c            | 162 +++++++++++++++++++++----
 arch/arm64/kvm/hyp/hyp-entry.S         |   6 +-
 arch/arm64/kvm/vgic/vgic-init.c        |  36 +++++-
 arch/arm64/kvm/vgic/vgic-v2.c          |  19 ++-
 arch/arm64/kvm/vgic/vgic-v3.c          |  19 ++-
 arch/arm64/kvm/vgic/vgic.c             |  14 +--
 drivers/irqchip/irq-apple-aic.c        |   9 ++
 drivers/irqchip/irq-gic-common.c       |  13 --
 drivers/irqchip/irq-gic-common.h       |   2 -
 drivers/irqchip/irq-gic-v3.c           |   6 +-
 drivers/irqchip/irq-gic.c              |   6 +-
 include/kvm/arm_vgic.h                 |  41 +++++--
 include/linux/irqchip/arm-gic-common.h |  25 +---
 include/linux/irqchip/arm-vgic-info.h  |  45 +++++++
 14 files changed, 299 insertions(+), 104 deletions(-)
 create mode 100644 include/linux/irqchip/arm-vgic-info.h

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