Re: [PATCH 4/6] KVM: Add KVM_(UN)REGISTER_COALESCED_MMIO2 ioctls

Paul Durrant
2024-07-13T06:19:28Z

On 10/07/2024 10:52, Ilias Stamatis wrote:
> Add 2 new ioctls, KVM_REGISTER_COALESCED_MMIO2 and
> KVM_UNREGISTER_COALESCED_MMIO2. These do the same thing as their v1
> equivalents except an fd returned by KVM_CREATE_COALESCED_MMIO_BUFFER
> needs to be passed as an argument to them.
>
> The fd representing a ring buffer is associated with an MMIO region
> registered for coalescing and all writes to that region are accumulated
> there. This is in contrast to the v1 API where all regions have to share
> the same buffer. Nevertheless, userspace code can still use the same
> ring buffer for multiple zones if it wishes to do so.
>
> Userspace can check for the availability of the new API by checking if
> the KVM_CAP_COALESCED_MMIO2 capability is supported.
>
> Signed-off-by: Ilias Stamatis <ilstam@amazon.com>
> ---
> include/uapi/linux/kvm.h | 16 ++++++++++++++++
> virt/kvm/coalesced_mmio.c | 36 ++++++++++++++++++++++++++++++------
> virt/kvm/coalesced_mmio.h | 7 ++++---
> virt/kvm/kvm_main.c | 36 +++++++++++++++++++++++++++++++++++-
> 4 files changed, 85 insertions(+), 10 deletions(-)
>

Reviewed-by: Paul Durrant <paul@xen.org>