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Re: [Qemu-ppc] [PATCH 3/4] spapr_iommu: Provide a function to switch a T
From: |
Laurent Vivier |
Subject: |
Re: [Qemu-ppc] [PATCH 3/4] spapr_iommu: Provide a function to switch a TCE table to allowing VFIO |
Date: |
Wed, 30 Sep 2015 11:33:41 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
On 30/09/2015 05:48, David Gibson wrote:
> Because of the way non-VFIO guest IOMMU operations are KVM accelerated, not
> all TCE tables (guest IOMMU contexts) can support VFIO devices. Currently,
> this is decided at creation time.
>
> To support hotplug of VFIO devices, we need to allow a TCE table which
> previously didn't allow VFIO devices to be switched so that it can. This
> patch adds an spapr_tce_set_need_vfio() function to do this, by
> reallocating the table in userspace if necessary.
>
> Currently this doesn't allow the KVM acceleration to be re-enabled if all
> the VFIO devices are removed. That's an optimization for another time.
>
> Signed-off-by: David Gibson <address@hidden>
> ---
> hw/ppc/spapr_iommu.c | 32 ++++++++++++++++++++++++++++++++
> include/hw/ppc/spapr.h | 2 ++
> 2 files changed, 34 insertions(+)
>
> diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
> index 5166cde..8d60f8b 100644
> --- a/hw/ppc/spapr_iommu.c
> +++ b/hw/ppc/spapr_iommu.c
> @@ -168,6 +168,38 @@ static int spapr_tce_table_realize(DeviceState *dev)
> return 0;
> }
>
> +void spapr_tce_set_need_vfio(sPAPRTCETable *tcet, bool need_vfio)
> +{
> + size_t table_size = tcet->nb_table * sizeof(uint64_t);
> + void *newtable;
> +
> + if (need_vfio == tcet->need_vfio) {
> + /* Nothing to do */
> + return;
> + }
> +
> + if (!need_vfio) {
> + /* FIXME: We don't support transition back to KVM accelerated
> + * TCEs yet */
Report some warnings ?
> + return;
> + }
> +
> + tcet->need_vfio = true;
> +
> + if (tcet->fd < 0) {
> + /* Table is already in userspace, nothing to be do */
> + return;
> + }
> +
> + newtable = g_malloc0(table_size);
> + memcpy(newtable, tcet->table, table_size);
> +
> + kvmppc_remove_spapr_tce(tcet->table, tcet->fd, tcet->nb_table);
> +
> + tcet->fd = -1;
> + tcet->table = newtable;
> +}
> +
> sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn,
> uint64_t bus_offset,
> uint32_t page_shift,
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 27d65d5..5baa906 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -589,6 +589,8 @@ sPAPRTCETable *spapr_tce_new_table(DeviceState *owner,
> uint32_t liobn,
> uint32_t page_shift,
> uint32_t nb_table,
> bool need_vfio);
> +void spapr_tce_set_need_vfio(sPAPRTCETable *tcet, bool need_vfio);
> +
> MemoryRegion *spapr_tce_get_iommu(sPAPRTCETable *tcet);
> int spapr_dma_dt(void *fdt, int node_off, const char *propname,
> uint32_t liobn, uint64_t window, uint32_t size);
>
Reviewed-by: Laurent Vivier <address@hidden>