Re: [RFC v7 5/7] KVM: arm/arm64: enable irqchip routing

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On 18/07/16 14:25, Eric Auger wrote:
> This patch adds compilation and link against irqchip.
> 
> Main motivation behind using irqchip code is to enable MSI
> routing code. In the future irqchip routing may also be useful
> when targeting multiple irqchips.
> 
> Routing standard callbacks now are implemented in vgic-irqfd:
> - kvm_set_routing_entry
> - kvm_set_irq
> - kvm_set_msi
> 
> They only are supported with new_vgic code.
> 
> Both HAVE_KVM_IRQCHIP and HAVE_KVM_IRQ_ROUTING are defined.
> KVM_CAP_IRQ_ROUTING is advertised and KVM_SET_GSI_ROUTING is allowed.
> 
> So from now on IRQCHIP routing is enabled and a routing table entry
> must exist for irqfd injection to succeed for a given SPI. This patch
> builds a default flat irqchip routing table (gsi=irqchip.pin) covering
> all the VGIC SPI indexes. This routing table is overwritten by the
> first first user-space call to KVM_SET_GSI_ROUTING ioctl.
> 
> MSI routing setup is not yet allowed.
> 
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
> 
> ---
> v6 -> v7:
> - re-introduce irq.h
> - use kvm_kernel_irq_routing_entry renamed fields: msi_flags, msi_devid
> - moved kvm_vgic_setup_default_irq_routing declaration in arm_vgic.h and
>   definition in vgic-irqfd.c
> - correct double / in Makefile
> - remove BUG_ON(!vgic_initialized(kvm) in vgic_irqfd_set_irq since
>   in any case we have a lazy_init in update_irq_pending
> - move KVM_IRQCHIP_NUM_PINS in arm_vgic.h
> - use VGIC_MAX_SPI
> 
> v5 -> v6:
> - rebase on top of Andre's v8 + removal of old vgic
> 
> v4 -> v5:
> - vgic_irqfd.c was renamed into vgic-irqfd.c by Andre
> - minor comment changes
> - remove trace_kvm_set_irq since it is called in irqchip
> - remove CONFIG_HAVE_KVM_MSI setting (done in KVM section)
> - despite Christoffer's question, in kvm_set_msi, I kept the copy from
>   the input "struct kvm_kernel_irq_routing_entry *e" imposed by the
>   irqchip callback API into the struct kvm_msi * passed to
>   vits_inject_msi. Since vits_inject_msi is directly called by
>   kvm_send_userspace_msi which takes a struct kvm_msi*, makes sense
>   to me to keep the copy.
> - squash former [PATCH v4 5/7] KVM: arm/arm64: build a default routing
>   table into that patch
> - handle default routing table alloc failure
> 
> v3 -> v4:
> - provide support only for new-vgic
> - code previously in vgic.c now in vgic_irqfd.c
> 
> v2 -> v3:
> - unconditionally set devid and KVM_MSI_VALID_DEVID flag as suggested
>   by Andre (KVM_IRQ_ROUTING_EXTENDED_MSI type not used anymore)
> - vgic_irqfd_set_irq now is static
> - propagate flags
> - add comments
> 
> v1 -> v2:
> - fix bug reported by Andre related to msi.flags and msi.devid setting
>   in kvm_send_userspace_msi
> - avoid injecting reserved IRQ numbers in vgic_irqfd_set_irq
> 
> RFC -> PATCH
> - reword api.txt:
>   x move MSI routing comments in a subsequent patch,
>   x clearly state GSI routing does not apply to KVM_IRQ_LINE
> ---
>  Documentation/virtual/kvm/api.txt |  12 +++--
>  arch/arm/kvm/Kconfig              |   2 +
>  arch/arm/kvm/Makefile             |   1 +
>  arch/arm/kvm/irq.h                |  19 +++++++
>  arch/arm64/kvm/Kconfig            |   2 +
>  arch/arm64/kvm/Makefile           |   1 +
>  arch/arm64/kvm/irq.h              |  19 +++++++
>  include/kvm/arm_vgic.h            |   7 +++
>  virt/kvm/arm/vgic/vgic-init.c     |   4 ++
>  virt/kvm/arm/vgic/vgic-irqfd.c    | 101 +++++++++++++++++++++++++++++++-------
>  virt/kvm/arm/vgic/vgic.c          |   7 ---
>  11 files changed, 146 insertions(+), 29 deletions(-)
>  create mode 100644 arch/arm/kvm/irq.h
>  create mode 100644 arch/arm64/kvm/irq.h
> 
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 0065c8e..3bb60d3 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -1433,13 +1433,16 @@ KVM_ASSIGN_DEV_IRQ. Partial deassignment of host or guest IRQ is allowed.
>  4.52 KVM_SET_GSI_ROUTING
>  
>  Capability: KVM_CAP_IRQ_ROUTING
> -Architectures: x86 s390
> +Architectures: x86 s390 arm arm64
>  Type: vm ioctl
>  Parameters: struct kvm_irq_routing (in)
>  Returns: 0 on success, -1 on error
>  
>  Sets the GSI routing table entries, overwriting any previously set entries.
>  
> +On arm/arm64, GSI routing has the following limitation:
> +- GSI routing does not apply to KVM_IRQ_LINE but only to KVM_IRQFD.
> +
>  struct kvm_irq_routing {
>  	__u32 nr;
>  	__u32 flags;
> @@ -2368,9 +2371,10 @@ Note that closing the resamplefd is not sufficient to disable the
>  irqfd.  The KVM_IRQFD_FLAG_RESAMPLE is only necessary on assignment
>  and need not be specified with KVM_IRQFD_FLAG_DEASSIGN.
>  
> -On ARM/ARM64, the gsi field in the kvm_irqfd struct specifies the Shared
> -Peripheral Interrupt (SPI) index, such that the GIC interrupt ID is
> -given by gsi + 32.
> +On arm/arm64, gsi routing being supported, the following can happen:
> +- in case no routing entry is associated to this gsi, injection fails
> +- in case the gsi is associated to an irqchip routing entry,
> +  irqchip.pin + 32 corresponds to the injected SPI ID.
>  
>  4.76 KVM_PPC_ALLOCATE_HTAB
>  
> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
> index 95a0005..3e1cd04 100644
> --- a/arch/arm/kvm/Kconfig
> +++ b/arch/arm/kvm/Kconfig
> @@ -32,6 +32,8 @@ config KVM
>  	select KVM_VFIO
>  	select HAVE_KVM_EVENTFD
>  	select HAVE_KVM_IRQFD
> +	select HAVE_KVM_IRQCHIP
> +	select HAVE_KVM_IRQ_ROUTING
>  	depends on ARM_VIRT_EXT && ARM_LPAE && ARM_ARCH_TIMER
>  	---help---
>  	  Support hosting virtualized guest machines.
> diff --git a/arch/arm/kvm/Makefile b/arch/arm/kvm/Makefile
> index 5e28df8..10d77a6 100644
> --- a/arch/arm/kvm/Makefile
> +++ b/arch/arm/kvm/Makefile
> @@ -29,4 +29,5 @@ obj-y += $(KVM)/arm/vgic/vgic-v2.o
>  obj-y += $(KVM)/arm/vgic/vgic-mmio.o
>  obj-y += $(KVM)/arm/vgic/vgic-mmio-v2.o
>  obj-y += $(KVM)/arm/vgic/vgic-kvm-device.o
> +obj-y += $(KVM)/irqchip.o
>  obj-y += $(KVM)/arm/arch_timer.o
> diff --git a/arch/arm/kvm/irq.h b/arch/arm/kvm/irq.h
> new file mode 100644
> index 0000000..b74099b
> --- /dev/null
> +++ b/arch/arm/kvm/irq.h
> @@ -0,0 +1,19 @@
> +/*
> + * irq.h: in kernel interrupt controller related definitions
> + * Copyright (c) 2016 Red Hat, Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This header is included by irqchip.c. However, on ARM, interrupt
> + * controller declarations are located in include/kvm/arm_vgic.h since
> + * they are mostly shared between arm and arm64.
> + */
> +
> +#ifndef __IRQ_H
> +#define __IRQ_H
> +
> +#include <kvm/arm_vgic.h>
> +
> +#endif
> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
> index 9d2eff0..9c9edc9 100644
> --- a/arch/arm64/kvm/Kconfig
> +++ b/arch/arm64/kvm/Kconfig
> @@ -37,6 +37,8 @@ config KVM
>  	select KVM_ARM_VGIC_V3
>  	select KVM_ARM_PMU if HW_PERF_EVENTS
>  	select HAVE_KVM_MSI
> +	select HAVE_KVM_IRQCHIP
> +	select HAVE_KVM_IRQ_ROUTING
>  	---help---
>  	  Support hosting virtualized guest machines.
>  	  We don't support KVM with 16K page tables yet, due to the multiple
> diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
> index a5b9664..695eb3c 100644
> --- a/arch/arm64/kvm/Makefile
> +++ b/arch/arm64/kvm/Makefile
> @@ -30,5 +30,6 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-mmio-v2.o
>  kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-mmio-v3.o
>  kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-kvm-device.o
>  kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-its.o
> +kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/irqchip.o
>  kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/arch_timer.o
>  kvm-$(CONFIG_KVM_ARM_PMU) += $(KVM)/arm/pmu.o
> diff --git a/arch/arm64/kvm/irq.h b/arch/arm64/kvm/irq.h
> new file mode 100644
> index 0000000..b74099b
> --- /dev/null
> +++ b/arch/arm64/kvm/irq.h
> @@ -0,0 +1,19 @@
> +/*
> + * irq.h: in kernel interrupt controller related definitions
> + * Copyright (c) 2016 Red Hat, Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This header is included by irqchip.c. However, on ARM, interrupt
> + * controller declarations are located in include/kvm/arm_vgic.h since
> + * they are mostly shared between arm and arm64.
> + */
> +
> +#ifndef __IRQ_H
> +#define __IRQ_H
> +
> +#include <kvm/arm_vgic.h>
> +
> +#endif
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index 4e63a07..260c8e9 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -34,6 +34,7 @@
>  #define VGIC_MAX_SPI		1019
>  #define VGIC_MAX_RESERVED	1023
>  #define VGIC_MIN_LPI		8192
> +#define KVM_IRQCHIP_NUM_PINS	(1020 - 32)
>  
>  enum vgic_type {
>  	VGIC_V2,		/* Good ol' GICv2 */
> @@ -313,4 +314,10 @@ static inline int kvm_vgic_get_max_vcpus(void)
>  
>  int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi);
>  
> +/**
> + * kvm_vgic_setup_default_irq_routing:
> + * Setup a default flat gsi routing table mapping all SPIs
> + */
> +int kvm_vgic_setup_default_irq_routing(struct kvm *kvm);
> +
>  #endif /* __KVM_ARM_VGIC_H */
> diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
> index 01a60dc..1aba785 100644
> --- a/virt/kvm/arm/vgic/vgic-init.c
> +++ b/virt/kvm/arm/vgic/vgic-init.c
> @@ -264,6 +264,10 @@ int vgic_init(struct kvm *kvm)
>  	kvm_for_each_vcpu(i, vcpu, kvm)
>  		kvm_vgic_vcpu_init(vcpu);
>  
> +	ret = kvm_vgic_setup_default_irq_routing(kvm);
> +	if (ret)
> +		goto out;
> +
>  	dist->initialized = true;
>  out:
>  	return ret;
> diff --git a/virt/kvm/arm/vgic/vgic-irqfd.c b/virt/kvm/arm/vgic/vgic-irqfd.c
> index c675513..c4750b7 100644
> --- a/virt/kvm/arm/vgic/vgic-irqfd.c
> +++ b/virt/kvm/arm/vgic/vgic-irqfd.c
> @@ -17,36 +17,101 @@
>  #include <linux/kvm.h>
>  #include <linux/kvm_host.h>
>  #include <trace/events/kvm.h>
> +#include <kvm/arm_vgic.h>
> +#include "vgic.h"
>  
> -int kvm_irq_map_gsi(struct kvm *kvm,
> -		    struct kvm_kernel_irq_routing_entry *entries,
> -		    int gsi)
> +/**
> + * vgic_irqfd_set_irq: inject the IRQ corresponding to the
> + * irqchip routing entry
> + *
> + * This is the entry point for irqfd IRQ injection
> + */
> +static int vgic_irqfd_set_irq(struct kvm_kernel_irq_routing_entry *e,
> +			struct kvm *kvm, int irq_source_id,
> +			int level, bool line_status)
>  {
> -	return 0;
> +	unsigned int spi_id = e->irqchip.pin + VGIC_NR_PRIVATE_IRQS;
> +	struct vgic_dist *dist = &kvm->arch.vgic;
> +
> +	if (spi_id > min(dist->nr_spis, VGIC_MAX_SPI))
> +		return -EINVAL;
> +	return kvm_vgic_inject_irq(kvm, 0, spi_id, level);
>  }
>  
> -int kvm_irq_map_chip_pin(struct kvm *kvm, unsigned int irqchip,
> -			 unsigned int pin)
> +/**
> + * kvm_set_routing_entry: populate a kvm routing entry
> + * from a user routing entry
> + *
> + * @e: kvm kernel routing entry handle
> + * @ue: user api routing entry handle
> + * return 0 on success, -EINVAL on errors.
> + */
> +int kvm_set_routing_entry(struct kvm_kernel_irq_routing_entry *e,
> +			  const struct kvm_irq_routing_entry *ue)

For the record, this fails to build with next, and I'm carrying the
following fix:

diff --git a/virt/kvm/arm/vgic/vgic-irqfd.c b/virt/kvm/arm/vgic/vgic-irqfd.c
index 28c96ad..1cacdcf 100644
--- a/virt/kvm/arm/vgic/vgic-irqfd.c
+++ b/virt/kvm/arm/vgic/vgic-irqfd.c
@@ -42,11 +42,13 @@ static int vgic_irqfd_set_irq(struct kvm_kernel_irq_routing_entry *e,
  * kvm_set_routing_entry: populate a kvm routing entry
  * from a user routing entry
  *
+ * @kvm: the associated VM struct
  * @e: kvm kernel routing entry handle
  * @ue: user api routing entry handle
  * return 0 on success, -EINVAL on errors.
  */
-int kvm_set_routing_entry(struct kvm_kernel_irq_routing_entry *e,
+int kvm_set_routing_entry(struct kvm *kvm,
+			  struct kvm_kernel_irq_routing_entry *e,
 			  const struct kvm_irq_routing_entry *ue)
 {
 	int r = -EINVAL;


Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...
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