On Fri, Feb 09, 2018 at 06:55:02PM +1100, Alexey Kardashevskiy wrote: > At the moment we unconditionally avoid mapping MSIX data of a BAR and > emulate MSIX table in QEMU. However it is 1) not always necessary as > a platform may prodive a paravirt interface for MSIX configuration; > 2) can affect the speed of MMIO access by emulating them in QEMU when > frequently accessed registers share same system page with MSIX data, > this is particularly a problem for systems with the page size bigger > than 4KB. > > A new capability - VFIO_REGION_INFO_CAP_MSIX_MAPPABLE - has been added > to the kernel [1] which tells the userspace that mapping of the MSIX data > is possible now. This makes use of it so from now on QEMU tries mapping > the entire BAR as a whole and emulate MSIX on top of that. > > [1] > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a32295c612c57990d17fb0f41e7134394b2f35f6 > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
> ---
> Changes:
> v7:
> * test iova/llsize against pgmask in vfio_listener_region_add/del
> * s/vfio_is_cap_present/vfio_has_region_cap/
> * added comments here and there
> * s/vdev->msix->table_bar/region-nr/
> ---
> include/hw/vfio/vfio-common.h | 1 +
> hw/vfio/common.c | 15 +++++++++++++++
> hw/vfio/pci.c | 9 +++++++++
> 3 files changed, 25 insertions(+)
>
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index f3a2ac9..42dd2b0 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -171,6 +171,7 @@ int vfio_get_region_info(VFIODevice *vbasedev, int index,
> struct vfio_region_info **info);
> int vfio_get_dev_region_info(VFIODevice *vbasedev, uint32_t type,
> uint32_t subtype, struct vfio_region_info
> **info);
> +bool vfio_has_region_cap(VFIODevice *vbasedev, int region, uint16_t
> cap_type);
> #endif
> extern const MemoryListener vfio_prereg_listener;
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 736f271..b99ae77 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -1464,6 +1464,21 @@ int vfio_get_dev_region_info(VFIODevice *vbasedev,
> uint32_t type,
> return -ENODEV;
> }
>
> +bool vfio_has_region_cap(VFIODevice *vbasedev, int region, uint16_t cap_type)
> +{
> + struct vfio_region_info *info = NULL;
> + bool ret = false;
> +
> + if (!vfio_get_region_info(vbasedev, region, &info)) {
> + if (vfio_get_region_info_cap(info, cap_type)) {
> + ret = true;
> + }
> + g_free(info);
> + }
> +
> + return ret;
> +}
> +
> /*
> * Interfaces for IBM EEH (Enhanced Error Handling)
> */
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 879510c..ae9098d 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -1294,6 +1294,15 @@ static void vfio_pci_fixup_msix_region(VFIOPCIDevice
> *vdev)
> VFIORegion *region = &vdev->bars[vdev->msix->table_bar].region;
>
> /*
> + * If the host driver allows mapping of a MSIX data, we are going to
> + * do map the entire BAR and emulate MSIX table on top of that.
> + */
> + if (vfio_has_region_cap(&vdev->vbasedev, region->nr,
> + VFIO_REGION_INFO_CAP_MSIX_MAPPABLE)) {
> + return;
> + }
> +
> + /*
> * We expect to find a single mmap covering the whole BAR, anything else
> * means it's either unsupported or already setup.
> */
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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