On 04/11/16 17:31, Andre Przywara wrote:
> When we set up GSI routing to map MSIs to KVM's GSI numbers, we
> write the current device's MSI setup into the kernel routing table.
> However the device driver in the guest can use PCI configuration space
> accesses to change the MSI configuration (address and/or payload data).
> Whenever this happens after we have setup the routing table already,
> we must amend the previously sent data.
> So when MSI-X PCI config space accesses write address or payload,
> find the associated GSI number and the matching routing table entry
> and update the kernel routing table (only if the data has changed).
>
> This fixes vhost-net, where the queue's IRQFD was setup before the
> MSI vectors.
>
> Signed-off-by: Andre Przywara <[email protected]>
> ---
> include/kvm/irq.h | 1 +
> irq.c | 31 +++++++++++++++++++++++++++++++
> virtio/pci.c | 36 +++++++++++++++++++++++++++++++++---
> 3 files changed, 65 insertions(+), 3 deletions(-)
>
> diff --git a/include/kvm/irq.h b/include/kvm/irq.h
> index bb71521..f35eb7e 100644
> --- a/include/kvm/irq.h
> +++ b/include/kvm/irq.h
> @@ -21,5 +21,6 @@ int irq__exit(struct kvm *kvm);
>
> int irq__allocate_routing_entry(void);
> int irq__add_msix_route(struct kvm *kvm, struct msi_msg *msg);
> +void irq__update_msix_route(struct kvm *kvm, u32 gsi, struct msi_msg *msg);
>
> #endif
> diff --git a/irq.c b/irq.c
> index a742aa2..895e5eb 100644
> --- a/irq.c
> +++ b/irq.c
> @@ -93,6 +93,37 @@ int irq__add_msix_route(struct kvm *kvm, struct msi_msg
> *msg)
> return next_gsi++;
> }
>
> +static bool update_data(u32 *ptr, u32 newdata)
> +{
> + if (*ptr == newdata)
> + return false;
> +
> + *ptr = newdata;
> + return true;
> +}
> +
> +void irq__update_msix_route(struct kvm *kvm, u32 gsi, struct msi_msg *msg)
> +{
> + struct kvm_irq_routing_msi *entry;
> + unsigned int i;
> + bool changed;
> +
> + for (i = 0; i < irq_routing->nr; i++)
> + if (gsi == irq_routing->entries[i].gsi)
> + break;
> + if (i == irq_routing->nr)
> + return;
> +
> + entry = &irq_routing->entries[i].u.msi;
> +
> + changed = update_data(&entry->address_hi, msg->address_hi);
> + changed |= update_data(&entry->address_lo, msg->address_lo);
> + changed |= update_data(&entry->data, msg->data);
> +
> + if (changed)
> + ioctl(kvm->vm_fd, KVM_SET_GSI_ROUTING, irq_routing);
Check the return value and let the caller know if something has failed?
> +}
> +
> int __attribute__((weak)) irq__exit(struct kvm *kvm)
> {
> free(irq_routing);
> diff --git a/virtio/pci.c b/virtio/pci.c
> index 072e5b7..b3b4aac 100644
> --- a/virtio/pci.c
> +++ b/virtio/pci.c
> @@ -152,6 +152,30 @@ static bool virtio_pci__io_in(struct ioport *ioport,
> struct kvm_cpu *vcpu, u16 p
> return ret;
> }
>
> +static void update_msix_map(struct virtio_pci *vpci,
> + struct msix_table *msix_entry, u32 vecnum)
> +{
> + u32 gsi, i;
> +
> + /* Find the GSI number used for that vector */
> + if (vecnum == vpci->config_vector) {
> + gsi = vpci->config_gsi;
> + } else {
> + for (i = 0; i < VIRTIO_PCI_MAX_VQ; i++)
> + if (vpci->vq_vector[i] == vecnum)
> + break;
> + if (i == VIRTIO_PCI_MAX_VQ)
> + return;
> + gsi = vpci->gsis[i];
> + }
> +
> + if (gsi == 0)
> + return;
> +
> + msix_entry = &msix_entry[vecnum];
> + irq__update_msix_route(vpci->kvm, gsi, &msix_entry->msg);
> +}
> +
> static bool virtio_pci__specific_io_out(struct kvm *kvm, struct
> virtio_device *vdev, u16 port,
> void *data, int size, int offset)
> {
> @@ -270,10 +294,16 @@ static void virtio_pci__msix_mmio_callback(struct
> kvm_cpu *vcpu,
> offset = vpci->msix_io_block;
> }
>
> - if (is_write)
> - memcpy(table + addr - offset, data, len);
> - else
> + if (!is_write) {
> memcpy(data, table + addr - offset, len);
> + return;
> + }
> +
> + memcpy(table + addr - offset, data, len);
> +
> + /* Did we just update the address or payload? */
> + if (addr % 0x10 < 0xc)
> + update_msix_map(vpci, table, (addr - offset) / 16);
Where are these constants coming from? Please stick to either decimal or
hex...
> }
>
> static void virtio_pci__signal_msi(struct kvm *kvm, struct virtio_pci *vpci,
> int vec)
>
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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