Re: [v4 13/16] KVM: x86: kvm-vfio: VT-d posted-interrupts setup

Alex Williamson
2015-06-11T17:16:11Z

On Thu, 2015-06-11 at 18:51 +0800, Feng Wu wrote:
> This patch defines macro __KVM_HAVE_ARCH_KVM_VFIO_POST and
> implement kvm_arch_vfio_update_pi_irte for x86 architecture.
>

What's vfio specific in any of this? It's obviously called from the
kvm-vfio device interface, but nothing below is vfio related. This is
simply the posted interrupt interface to kvm. Thanks,

Alex

> Signed-off-by: Feng Wu <feng.wu@intel.com>
> ---
> arch/x86/include/asm/kvm_host.h | 2 +
> arch/x86/kvm/Makefile | 3 +-
> arch/x86/kvm/kvm_vfio_x86.c | 85 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 89 insertions(+), 1 deletion(-)
> create mode 100644 arch/x86/kvm/kvm_vfio_x86.c
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 31a495f..1605bf8 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -81,6 +81,8 @@ static inline gfn_t gfn_to_index(gfn_t gfn, gfn_t base_gfn, int level)
> (base_gfn >> KVM_HPAGE_GFN_SHIFT(level));
> }
>
> +#define __KVM_HAVE_ARCH_KVM_VFIO_POST
> +
> #define KVM_PERMILLE_MMU_PAGES 20
> #define KVM_MIN_ALLOC_MMU_PAGES 64
> #define KVM_MMU_HASH_SHIFT 10
> diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
> index 16e8f96..6bafc89 100644
> --- a/arch/x86/kvm/Makefile
> +++ b/arch/x86/kvm/Makefile
> @@ -12,7 +12,8 @@ kvm-y += $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o \
> kvm-$(CONFIG_KVM_ASYNC_PF) += $(KVM)/async_pf.o
>
> kvm-y += x86.o mmu.o emulate.o i8259.o irq.o lapic.o \
> - i8254.o ioapic.o irq_comm.o cpuid.o pmu.o
> + i8254.o ioapic.o irq_comm.o cpuid.o pmu.o \
> + kvm_vfio_x86.o
> kvm-$(CONFIG_KVM_DEVICE_ASSIGNMENT) += assigned-dev.o iommu.o
> kvm-intel-y += vmx.o
> kvm-amd-y += svm.o
> diff --git a/arch/x86/kvm/kvm_vfio_x86.c b/arch/x86/kvm/kvm_vfio_x86.c
> new file mode 100644
> index 0000000..a2d74f9
> --- /dev/null
> +++ b/arch/x86/kvm/kvm_vfio_x86.c
> @@ -0,0 +1,85 @@
> +/*
> + * Copyright (C) 2014 Intel Corporation.
> + * Authors: Feng Wu <feng.wu@intel.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License, version 2, as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/kvm_host.h>
> +#include <asm/irq_remapping.h>
> +
> +/*
> + * kvm_arch_vfio_update_pi_irte - set IRTE for Posted-Interrupts
> + *
> + * @kvm: kvm
> + * @host_irq: host irq of the interrupt
> + * @guest_irq: gsi of the interrupt
> + * @set: set or unset PI
> + * returns 0 on success, < 0 on failure
> + */
> +int kvm_arch_vfio_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
> + uint32_t guest_irq, bool set)
> +{
> + struct kvm_kernel_irq_routing_entry *e;
> + struct kvm_irq_routing_table *irq_rt;
> + struct kvm_lapic_irq irq;
> + struct kvm_vcpu *vcpu;
> + struct vcpu_data vcpu_info;
> + int idx, ret = -EINVAL;
> +
> + idx = srcu_read_lock(&kvm->irq_srcu);
> + irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
> + BUG_ON(guest_irq >= irq_rt->nr_rt_entries);
> +
> + hlist_for_each_entry(e, &irq_rt->map[guest_irq], link) {
> + if (e->type != KVM_IRQ_ROUTING_MSI)
> + continue;
> + /*
> + * VT-d PI cannot support posting multicast/broadcast
> + * interrupts to a VCPU, we still use interrupt remapping
> + * for these kind of interrupts.
> + *
> + * For lowest-priority interrupts, we only support
> + * those with single CPU as the destination, e.g. user
> + * configures the interrupts via /proc/irq or uses
> + * irqbalance to make the interrupts single-CPU.
> + *
> + * We will support full lowest-priority interrupt later.
> + *
> + */
> +
> + kvm_set_msi_irq(e, &irq);
> + if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu))
> + continue;
> +
> + vcpu_info.pi_desc_addr = kvm_x86_ops->get_pi_desc_addr(vcpu);
> + vcpu_info.vector = irq.vector;
> +
> + if (set)
> + ret = irq_set_vcpu_affinity(host_irq, &vcpu_info);
> + else {
> + /* suppress notification event before unposting */
> + kvm_x86_ops->pi_set_sn(vcpu);
> + ret = irq_set_vcpu_affinity(host_irq, NULL);
> + kvm_x86_ops->pi_clear_sn(vcpu);
> + }
> +
> + if (ret < 0) {
> + printk(KERN_INFO "%s: failed to update PI IRTE\n",
> + __func__);
> + goto out;
> + }
> + }
> +
> + ret = 0;
> +out:
> + srcu_read_unlock(&kvm->irq_srcu, idx);
> + return ret;
> +}