On Wed, 23 Nov 2022 12:08:05 +0000 Marc Zyngier <maz@xxxxxxxxxx> wrote: > On Wed, 23 Nov 2022 01:42:36 +0000, > chenxiang <chenxiang66@xxxxxxxxxxxxx> wrote: > > > > From: Xiang Chen <chenxiang66@xxxxxxxxxxxxx> > > > > Currently the number of MSI vectors comes from register PCI_MSI_FLAGS > > which should be power-of-2 in qemu, in some scenaries it is not the same as > > the number that driver requires in guest, for example, a PCI driver wants > > to allocate 6 MSI vecotrs in guest, but as the limitation, it will allocate > > 8 MSI vectors. So it requires 8 MSI vectors in qemu while the driver in > > guest only wants to allocate 6 MSI vectors. > > > > When GICv4.1 is enabled, it iterates over all possible MSIs and enable the > > forwarding while the guest has only created some of mappings in the virtual > > ITS, so some calls fail. The exception print is as following: > > vfio-pci 0000:3a:00.1: irq bypass producer (token 000000008f08224d) registration > > fails:66311 > > > > To avoid the issue, verify each MSI vector, skip some operations such as > > request_irq() and irq_bypass_register_producer() for those invalid MSI vectors. > > > > Signed-off-by: Xiang Chen <chenxiang66@xxxxxxxxxxxxx> > > --- > > I reported the issue at the link: > > https://lkml.kernel.org/lkml/87cze9lcut.wl-maz@xxxxxxxxxx/T/ > > > > Change Log: > > v1 -> v2: > > Verify each MSI vector in kernel instead of adding systemcall according to > > Mar's suggestion > > --- > > arch/arm64/kvm/vgic/vgic-irqfd.c | 13 +++++++++++++ > > arch/arm64/kvm/vgic/vgic-its.c | 36 ++++++++++++++++++++++++++++++++++++ > > arch/arm64/kvm/vgic/vgic.h | 1 + > > drivers/vfio/pci/vfio_pci_intrs.c | 33 +++++++++++++++++++++++++++++++++ > > include/linux/kvm_host.h | 2 ++ > > 5 files changed, 85 insertions(+) > > > > diff --git a/arch/arm64/kvm/vgic/vgic-irqfd.c b/arch/arm64/kvm/vgic/vgic-irqfd.c > > index 475059b..71f6af57 100644 > > --- a/arch/arm64/kvm/vgic/vgic-irqfd.c > > +++ b/arch/arm64/kvm/vgic/vgic-irqfd.c > > @@ -98,6 +98,19 @@ int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e, > > return vgic_its_inject_msi(kvm, &msi); > > } > > > > +int kvm_verify_msi(struct kvm *kvm, > > + struct kvm_kernel_irq_routing_entry *irq_entry) > > +{ > > + struct kvm_msi msi; > > + > > + if (!vgic_has_its(kvm)) > > + return -ENODEV; > > + > > + kvm_populate_msi(irq_entry, &msi); > > + > > + return vgic_its_verify_msi(kvm, &msi); > > +} > > + > > /** > > * kvm_arch_set_irq_inatomic: fast-path for irqfd injection > > */ > > diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c > > index 94a666d..8312a4a 100644 > > --- a/arch/arm64/kvm/vgic/vgic-its.c > > +++ b/arch/arm64/kvm/vgic/vgic-its.c > > @@ -767,6 +767,42 @@ int vgic_its_inject_cached_translation(struct kvm *kvm, struct kvm_msi *msi) > > return 0; > > } > > > > +int vgic_its_verify_msi(struct kvm *kvm, struct kvm_msi *msi) > > +{ > > + struct vgic_its *its; > > + struct its_ite *ite; > > + struct kvm_vcpu *vcpu; > > + int ret = 0; > > + > > + if (!irqchip_in_kernel(kvm) || (msi->flags & ~KVM_MSI_VALID_DEVID)) > > + return -EINVAL; > > + > > + if (!vgic_has_its(kvm)) > > + return -ENODEV; > > + > > + its = vgic_msi_to_its(kvm, msi); > > + if (IS_ERR(its)) > > + return PTR_ERR(its); > > + > > + mutex_lock(&its->its_lock); > > + if (!its->enabled) { > > + ret = -EBUSY; > > + goto unlock; > > + } > > + ite = find_ite(its, msi->devid, msi->data); > > + if (!ite || !its_is_collection_mapped(ite->collection)) { > > + ret = E_ITS_INT_UNMAPPED_INTERRUPT; > > + goto unlock; > > + } > > + > > + vcpu = kvm_get_vcpu(kvm, ite->collection->target_addr); > > + if (!vcpu) > > + ret = E_ITS_INT_UNMAPPED_INTERRUPT; > > I'm sorry, but what does this mean to the caller? This should never > leak outside of the ITS code. > > > +unlock: > > + mutex_unlock(&its->its_lock); > > + return ret; > > +} > > + > > /* > > * Queries the KVM IO bus framework to get the ITS pointer from the given > > * doorbell address. > > diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h > > index 0c8da72..d452150 100644 > > --- a/arch/arm64/kvm/vgic/vgic.h > > +++ b/arch/arm64/kvm/vgic/vgic.h > > @@ -240,6 +240,7 @@ int kvm_vgic_register_its_device(void); > > void vgic_enable_lpis(struct kvm_vcpu *vcpu); > > void vgic_flush_pending_lpis(struct kvm_vcpu *vcpu); > > int vgic_its_inject_msi(struct kvm *kvm, struct kvm_msi *msi); > > +int vgic_its_verify_msi(struct kvm *kvm, struct kvm_msi *msi); > > int vgic_v3_has_attr_regs(struct kvm_device *dev, struct kvm_device_attr *attr); > > int vgic_v3_dist_uaccess(struct kvm_vcpu *vcpu, bool is_write, > > int offset, u32 *val); > > diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c > > index 40c3d7c..3027805 100644 > > --- a/drivers/vfio/pci/vfio_pci_intrs.c > > +++ b/drivers/vfio/pci/vfio_pci_intrs.c > > @@ -19,6 +19,7 @@ > > #include <linux/vfio.h> > > #include <linux/wait.h> > > #include <linux/slab.h> > > +#include <linux/kvm_irqfd.h> > > > > #include "vfio_pci_priv.h" > > > > @@ -315,6 +316,28 @@ static int vfio_msi_enable(struct vfio_pci_core_device *vdev, int nvec, bool msi > > return 0; > > } > > > > +static int vfio_pci_verify_msi_entry(struct vfio_pci_core_device *vdev, > > + struct eventfd_ctx *trigger) > > +{ > > + struct kvm *kvm = vdev->vdev.kvm; > > + struct kvm_kernel_irqfd *tmp; > > + struct kvm_kernel_irq_routing_entry irq_entry; > > + int ret = -ENODEV; > > + > > + spin_lock_irq(&kvm->irqfds.lock); > > + list_for_each_entry(tmp, &kvm->irqfds.items, list) { > > + if (trigger == tmp->eventfd) { > > + ret = 0; > > + break; > > + } > > + } > > + spin_unlock_irq(&kvm->irqfds.lock); > > + if (ret) > > + return ret; > > + irq_entry = tmp->irq_entry; > > + return kvm_verify_msi(kvm, &irq_entry); > > How does this work on !arm64? Why do we need an on-stack version of > tmp->irq_entry? Not only on !arm64, but in any scenario that doesn't involve KVM. There cannot be a hard dependency between vfio and kvm. Thanks, Alex PS - What driver/device actually cares about more than 1 MSI vector and doesn't implement MSI-X? > > > +} > > + > > static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev, > > int vector, int fd, bool msix) > > { > > @@ -355,6 +378,16 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev, > > return PTR_ERR(trigger); > > } > > > > + if (!msix) { > > + ret = vfio_pci_verify_msi_entry(vdev, trigger); > > + if (ret) { > > + kfree(vdev->ctx[vector].name); > > + eventfd_ctx_put(trigger); > > + if (ret > 0) > > + ret = 0; > > + return ret; > > + } > > + } > > Honestly, the whole things seems really complicated to avoid something > that is only a harmless warning . How about just toning down the > message instead? > > M. >
