Hi,
On 09/12/16 17:13, Marc Zyngier wrote:
> 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?
As the caller is a void function and the call chain for this originates
in an MMIO access triggered by the guest (update MSI information in the
PCI config space), I guess again die() would be the appropriate action here?
>
>> +}
>> +
>> 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...
Sure, seems to be a leftover from my initial hacking approach. Thanks
for spotting that.
Cheers,
Andre.
>
>> }
>>
>> static void virtio_pci__signal_msi(struct kvm *kvm, struct virtio_pci
>> *vpci, int vec)
>>
>
> Thanks,
>
> M.
>
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