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Re: [Qemu-ppc] [PATCH qemu v16 18/19] vfio/spapr: Create DMA window dyna
From: |
David Gibson |
Subject: |
Re: [Qemu-ppc] [PATCH qemu v16 18/19] vfio/spapr: Create DMA window dynamically (SPAPR IOMMU v2) |
Date: |
Fri, 27 May 2016 14:05:00 +1000 |
User-agent: |
Mutt/1.6.1 (2016-04-27) |
On Fri, May 27, 2016 at 01:49:19PM +1000, Alexey Kardashevskiy wrote:
> On 17/05/16 06:20, Alex Williamson wrote:
> > On Mon, 16 May 2016 14:52:41 +1000
> > Alexey Kardashevskiy <address@hidden> wrote:
> >
> >> On 05/14/2016 08:26 AM, Alex Williamson wrote:
> >>> On Wed, 4 May 2016 16:52:30 +1000
> >>> Alexey Kardashevskiy <address@hidden> wrote:
> >>>
> >>>> New VFIO_SPAPR_TCE_v2_IOMMU type supports dynamic DMA window management.
> >>>> This adds ability to VFIO common code to dynamically allocate/remove
> >>>> DMA windows in the host kernel when new VFIO container is added/removed.
> >>>>
> >>>> This adds VFIO_IOMMU_SPAPR_TCE_CREATE ioctl to vfio_listener_region_add
> >>>> and adds just created IOMMU into the host IOMMU list; the opposite
> >>>> action is taken in vfio_listener_region_del.
> >>>>
> >>>> When creating a new window, this uses heuristic to decide on the TCE
> >>>> table
> >>>> levels number.
> >>>>
> >>>> This should cause no guest visible change in behavior.
> >>>>
> >>>> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> >>>> ---
> >>>> Changes:
> >>>> v16:
> >>>> * used memory_region_iommu_get_page_sizes() in vfio_listener_region_add()
> >>>> * enforced no intersections between windows
> >>>>
> >>>> v14:
> >>>> * new to the series
> >>>> ---
> >>>> hw/vfio/common.c | 133
> >>>> ++++++++++++++++++++++++++++++++++++++++++++++++++-----
> >>>> trace-events | 2 +
> >>>> 2 files changed, 125 insertions(+), 10 deletions(-)
> >>>>
> >>>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> >>>> index 03daf88..bd2dee8 100644
> >>>> --- a/hw/vfio/common.c
> >>>> +++ b/hw/vfio/common.c
> >>>> @@ -240,6 +240,18 @@ static int vfio_dma_map(VFIOContainer *container,
> >>>> hwaddr iova,
> >>>> return -errno;
> >>>> }
> >>>>
> >>>> +static bool range_contains(hwaddr start, hwaddr end, hwaddr addr)
> >>>> +{
> >>>> + return start <= addr && addr <= end;
> >>>> +}
> >>>
> >>> a) If you want a "range_foo" function then put it in range.h
> >>> b) I suspect there are already range.h functions that can do this.
> >>>
> >>>> +
> >>>> +static bool vfio_host_win_intersects(VFIOHostDMAWindow *hostwin,
> >>>> + hwaddr min_iova, hwaddr max_iova)
> >>>> +{
> >>>> + return range_contains(hostwin->min_iova, hostwin->min_iova,
> >>>> min_iova) ||
> >>>> + range_contains(min_iova, max_iova, hostwin->min_iova);
> >>>> +}
> >>>
> >>> How is this different than ranges_overlap()?
> >>>> +
> >>>> static VFIOHostDMAWindow *vfio_host_win_lookup(VFIOContainer *container,
> >>>> hwaddr min_iova, hwaddr
> >>>> max_iova)
> >>>> {
> >>>> @@ -279,6 +291,14 @@ static int vfio_host_win_add(VFIOContainer
> >>>> *container,
> >>>> return 0;
> >>>> }
> >>>>
> >>>> +static void vfio_host_win_del(VFIOContainer *container, hwaddr min_iova)
> >>>> +{
> >>>> + VFIOHostDMAWindow *hostwin = vfio_host_win_lookup(container,
> >>>> min_iova, 1);
> >>>> +
> >>>> + g_assert(hostwin);
> >>>
> >>> Handle the error please.
> >>
> >> Will this be enough?
> >>
> >> if (!hostwin) {
> >> error_report("%s: Cannot delete missing window at %"HWADDR_PRIx,
> >> __func__, min_iova);
> >> return;
> >> }
> >
> > Better. I was really thinking to return error to the caller, but if
> > the caller has no return path, perhaps this is as good as we can do.
> > Expect that I will push back on any assert() calls added to vfio.
> >
> >
> >>>> + QLIST_REMOVE(hostwin, hostwin_next);
> >>>> +}
> >>>> +
> >>>> static bool vfio_listener_skipped_section(MemoryRegionSection *section)
> >>>> {
> >>>> return (!memory_region_is_ram(section->mr) &&
> >>>> @@ -392,6 +412,69 @@ static void vfio_listener_region_add(MemoryListener
> >>>> *listener,
> >>>> }
> >>>> end = int128_get64(int128_sub(llend, int128_one()));
> >>>>
> >>>> + if (container->iommu_type == VFIO_SPAPR_TCE_v2_IOMMU) {
> >>>> + VFIOHostDMAWindow *hostwin;
> >>>> + unsigned pagesizes =
> >>>> memory_region_iommu_get_page_sizes(section->mr);
> >>>> + unsigned pagesize = (hwaddr)1 << ctz64(pagesizes);
> >>>> + unsigned entries, pages;
> >>>> + struct vfio_iommu_spapr_tce_create create = { .argsz =
> >>>> sizeof(create) };
> >>>> +
> >>>> + trace_vfio_listener_region_add_iommu(iova, end);
> >>>> + /*
> >>>> + * FIXME: For VFIO iommu types which have KVM acceleration to
> >>>> + * avoid bouncing all map/unmaps through qemu this way, this
> >>>> + * would be the right place to wire that up (tell the KVM
> >>>> + * device emulation the VFIO iommu handles to use).
> >>>> + */
> >>>> + create.window_size = int128_get64(section->size);
> >>>> + create.page_shift = ctz64(pagesize);
> >>>> + /*
> >>>> + * SPAPR host supports multilevel TCE tables, there is some
> >>>> + * heuristic to decide how many levels we want for our table:
> >>>> + * 0..64 = 1; 65..4096 = 2; 4097..262144 = 3; 262145.. = 4
> >>>> + */
> >>>> + entries = create.window_size >> create.page_shift;
> >>>> + pages = MAX((entries * sizeof(uint64_t)) / getpagesize(), 1);
> >>>> + pages = MAX(pow2ceil(pages) - 1, 1); /* Round up */
> >>>> + create.levels = ctz64(pages) / 6 + 1;
> >>>> +
> >>>> + /* For now intersections are not allowed, we may relax this
> >>>> later */
> >>>> + QLIST_FOREACH(hostwin, &container->hostwin_list, hostwin_next) {
> >>>> + if (vfio_host_win_intersects(hostwin,
> >>>> + section->offset_within_address_space,
> >>>> + section->offset_within_address_space +
> >>>> + create.window_size - 1)) {
> >>>> + goto fail;
> >>>> + }
> >>>> + }
> >>>> +
> >>>> + ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_CREATE,
> >>>> &create);
> >>>> + if (ret) {
> >>>> + error_report("Failed to create a window, ret = %d (%m)",
> >>>> ret);
> >>>> + goto fail;
> >>>> + }
> >>>> +
> >>>> + if (create.start_addr != section->offset_within_address_space) {
> >>>> + struct vfio_iommu_spapr_tce_remove remove = {
> >>>> + .argsz = sizeof(remove),
> >>>> + .start_addr = create.start_addr
> >>>> + };
> >>>> + error_report("Host doesn't support DMA window at
> >>>> %"HWADDR_PRIx", must be %"PRIx64,
> >>>> + section->offset_within_address_space,
> >>>> + create.start_addr);
> >>>> + ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_REMOVE, &remove);
> >>>> + ret = -EINVAL;
> >>>> + goto fail;
> >>>> + }
> >>>> + trace_vfio_spapr_create_window(create.page_shift,
> >>>> + create.window_size,
> >>>> + create.start_addr);
> >>>> +
> >>>> + vfio_host_win_add(container, create.start_addr,
> >>>> + create.start_addr + create.window_size - 1,
> >>>> + 1ULL << create.page_shift);
> >>>> + }
> >>>
> >>> This is a function on its own, split it out and why not stop pretending
> >>> prereg is some sort of generic interface and let's just make a spapr
> >>> support file.
> >>
> >>
> >> Yet another new file - spapr.c, or rename prereg.c to spapr.c and add this
> >> stuff there?
> >
> > prereg.c is already spapr specific, so I'd rename it and potentially
> > add this to it.
>
>
> It would help if you two decided what I should do about prereg.c vs.
> spapr.c - merge or keep 2 files. Thanks.
I'm not particularly fussed either way. So I suggest putting the
prereg stuff in spapr.c for now, and we can move it out if/when
another platform starts using the mechanism.
--
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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[Qemu-ppc] [PATCH qemu v16 18/19] vfio/spapr: Create DMA window dynamically (SPAPR IOMMU v2), Alexey Kardashevskiy, 2016/05/04
[Qemu-ppc] [PATCH qemu v16 01/19] vfio: Delay DMA address space listener release, Alexey Kardashevskiy, 2016/05/04
- Re: [Qemu-ppc] [PATCH qemu v16 01/19] vfio: Delay DMA address space listener release, Alex Williamson, 2016/05/05
- Re: [Qemu-ppc] [PATCH qemu v16 01/19] vfio: Delay DMA address space listener release, Alexey Kardashevskiy, 2016/05/13
- Re: [Qemu-ppc] [PATCH qemu v16 01/19] vfio: Delay DMA address space listener release, Alex Williamson, 2016/05/13
- Re: [Qemu-ppc] [PATCH qemu v16 01/19] vfio: Delay DMA address space listener release, David Gibson, 2016/05/25
- Re: [Qemu-ppc] [PATCH qemu v16 01/19] vfio: Delay DMA address space listener release, Alex Williamson, 2016/05/25
- Re: [Qemu-ppc] [PATCH qemu v16 01/19] vfio: Delay DMA address space listener release, David Gibson, 2016/05/25
[Qemu-ppc] [PATCH qemu v16 06/19] spapr_pci: Use correct DMA LIOBN when composing the device tree, Alexey Kardashevskiy, 2016/05/04
[Qemu-ppc] [PATCH qemu v16 15/19] spapr_pci: Add and export DMA resetting helper, Alexey Kardashevskiy, 2016/05/04