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

[Wu, Feng]

> -----Original Message-----
> From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx]
> Sent: Friday, June 12, 2015 1:16 AM
> To: Wu, Feng
> Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; pbonzini@xxxxxxxxxx;
> mtosatti@xxxxxxxxxx; eric.auger@xxxxxxxxxx
> Subject: Re: [v4 13/16] KVM: x86: kvm-vfio: VT-d posted-interrupts setup
> 
> 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
> 

Oh, yes, maybe I need to move this part to vmx.c.

Thanks,
Feng

> 
> > Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
> > ---
> >  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@xxxxxxxxx>
> > + *
> > + * 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;
> > +}
> 
>