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Re: [Qemu-ppc] [PATCH qemu v17 10/12] vfio/spapr: Create DMA window dyna
From: |
David Gibson |
Subject: |
Re: [Qemu-ppc] [PATCH qemu v17 10/12] vfio/spapr: Create DMA window dynamically (SPAPR IOMMU v2) |
Date: |
Wed, 8 Jun 2016 15:56:02 +1000 |
User-agent: |
Mutt/1.6.1 (2016-04-27) |
On Mon, Jun 06, 2016 at 04:45:50PM +1000, Alexey Kardashevskiy wrote:
> On 03/06/16 17:37, David Gibson wrote:
> > On Wed, Jun 01, 2016 at 06:57:41PM +1000, Alexey Kardashevskiy 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:
> >> v17:
> >> * moved spapr window create/remove helpers to separate file
> >> * added hw_error() if vfio_host_win_del() failed
> >>
> >> 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 | 76
> >> +++++++++++++++++++++++++++++++++++++------
> >> hw/vfio/spapr.c | 70 +++++++++++++++++++++++++++++++++++++++
> >> include/hw/vfio/vfio-common.h | 6 ++++
> >> trace-events | 2 ++
> >> 4 files changed, 144 insertions(+), 10 deletions(-)
> >>
> >> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> >> index 52b08fd..7f55c26 100644
> >> --- a/hw/vfio/common.c
> >> +++ b/hw/vfio/common.c
> >> @@ -275,6 +275,18 @@ static void vfio_host_win_add(VFIOContainer
> >> *container,
> >> QLIST_INSERT_HEAD(&container->hostwin_list, hostwin, hostwin_next);
> >> }
> >>
> >> +static int vfio_host_win_del(VFIOContainer *container, hwaddr min_iova)
> >> +{
> >> + VFIOHostDMAWindow *hostwin = vfio_host_win_lookup(container,
> >> min_iova, 1);
> >
> > Hrm.. and for this case I think you want exact match, rather than
> > looking for range inclusion.
>
> I suppose so, I'll change this.
>
>
> >> +
> >> + if (!hostwin) {
> >> + return -1;
> >> + }
> >> + QLIST_REMOVE(hostwin, hostwin_next);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> static bool vfio_listener_skipped_section(MemoryRegionSection *section)
> >> {
> >> return (!memory_region_is_ram(section->mr) &&
> >> @@ -388,6 +400,30 @@ 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;
> >> + hwaddr pgsize = 0;
> >> +
> >> + /* For now intersections are not allowed, we may relax this later
> >> */
> >> + QLIST_FOREACH(hostwin, &container->hostwin_list, hostwin_next) {
> >> + if (ranges_overlap(hostwin->min_iova,
> >> + hostwin->max_iova - hostwin->min_iova + 1,
> >> + section->offset_within_address_space,
> >> + int128_get64(section->size))) {
> >> + goto fail;
> >> + }
> >> + }
> >> +
> >> + ret = vfio_spapr_create_window(container, section, &pgsize);
> >> + if (ret) {
> >> + goto fail;
> >> + }
> >> +
> >> + vfio_host_win_add(container, section->offset_within_address_space,
> >> + section->offset_within_address_space +
> >> + int128_get64(section->size) - 1, pgsize);
> >> + }
> >> +
> >> if (!vfio_host_win_lookup(container, iova, end)) {
> >> error_report("vfio: IOMMU container %p can't map guest IOVA
> >> region"
> >> " 0x%"HWADDR_PRIx"..0x%"HWADDR_PRIx,
> >> @@ -523,6 +559,18 @@ static void vfio_listener_region_del(MemoryListener
> >> *listener,
> >> "0x%"HWADDR_PRIx") = %d (%m)",
> >> container, iova, int128_get64(llsize), ret);
> >> }
> >> +
> >> + if (container->iommu_type == VFIO_SPAPR_TCE_v2_IOMMU) {
> >> + vfio_spapr_remove_window(container,
> >> + section->offset_within_address_space);
> >
> > Should check for error here.
>
>
> And do what here? vfio_spapr_remove_window() calls error_report() already
> and I still want to remove the host window here.
Hmm.. yes, I guess so. Probably best to have a comment here saying
why it's safe to ignore an error you should usually test for.
> >
> >> + if (vfio_host_win_del(container,
> >> + section->offset_within_address_space) < 0) {
> >> + hw_error("%s: Cannot delete missing window at %"HWADDR_PRIx,
> >> + __func__, section->offset_within_address_space);
> >
> > Personally I think assert() would be better here, but Alex doesn't
> > like them so I'm ok with this.
> >
> >> + }
> >> +
> >> +
> >> trace_vfio_spapr_remove_window(section->offset_within_address_space);
> >> + }
> >> }
> >>
> >> static const MemoryListener vfio_memory_listener = {
> >> @@ -960,11 +1008,6 @@ static int vfio_connect_container(VFIOGroup *group,
> >> AddressSpace *as)
> >> }
> >> }
> >>
> >> - /*
> >> - * This only considers the host IOMMU's 32-bit window. At
> >> - * some point we need to add support for the optional 64-bit
> >> - * window and dynamic windows
> >> - */
> >> info.argsz = sizeof(info);
> >> ret = ioctl(fd, VFIO_IOMMU_SPAPR_TCE_GET_INFO, &info);
> >> if (ret) {
> >> @@ -973,11 +1016,24 @@ static int vfio_connect_container(VFIOGroup *group,
> >> AddressSpace *as)
> >> goto listener_release_exit;
> >> }
> >>
> >> - /* The default table uses 4K pages */
> >> - vfio_host_win_add(container, info.dma32_window_start,
> >> - info.dma32_window_start +
> >> - info.dma32_window_size - 1,
> >> - 0x1000);
> >> + if (v2) {
> >> + /*
> >> + * There is a default window in just created container.
> >> + * To make region_add/del simpler, we better remove this
> >> + * window now and let those iommu_listener callbacks
> >> + * create/remove them when needed.
> >> + */
> >> + ret = vfio_spapr_remove_window(container,
> >> info.dma32_window_start);
> >> + if (ret) {
> >> + goto free_container_exit;
> >> + }
> >> + } else {
> >> + /* The default table uses 4K pages */
> >> + vfio_host_win_add(container, info.dma32_window_start,
> >> + info.dma32_window_start +
> >> + info.dma32_window_size - 1,
> >> + 0x1000);
> >> + }
> >> } else {
> >> error_report("vfio: No available IOMMU models");
> >> ret = -EINVAL;
> >> diff --git a/hw/vfio/spapr.c b/hw/vfio/spapr.c
> >> index f339472..0c784c4 100644
> >> --- a/hw/vfio/spapr.c
> >> +++ b/hw/vfio/spapr.c
> >> @@ -135,3 +135,73 @@ const MemoryListener vfio_prereg_listener = {
> >> .region_add = vfio_prereg_listener_region_add,
> >> .region_del = vfio_prereg_listener_region_del,
> >> };
> >> +
> >> +int vfio_spapr_create_window(VFIOContainer *container,
> >> + MemoryRegionSection *section,
> >> + hwaddr *pgsize)
> >> +{
> >> + int ret;
> >> + 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)
> >> };
> >> +
> >> + /*
> >> + * 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);
> >
> > Doing a ctz on a value which is defined as 1 << n seems a bit
> > perverse.
>
> Well, this way it felt more obvious that pagesize is a single page size,
> not a mask. Not sure if memory_region_iommu_get_page_sizes() returning a
> mask (rather than a page size) is a good idea after all...
>
> I'll make it:
>
> create.page_shift = ctz64(pagesizes);
>
> and (below):
>
> *pgsize = 1ULL << create.page_shift;
Yes, I think that's better.
> and remove 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;
> >> +
> >> + ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_CREATE, &create);
> >> + if (ret) {
> >> + error_report("Failed to create a window, ret = %d (%m)", ret);
> >> + return -errno;
> >> + }
> >> +
> >> + if (create.start_addr != section->offset_within_address_space) {
> >> + vfio_spapr_remove_window(container, 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);
> >> + return -EINVAL;
> >> + }
> >> + trace_vfio_spapr_create_window(create.page_shift,
> >> + create.window_size,
> >> + create.start_addr);
> >> + *pgsize = pagesize;
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +int vfio_spapr_remove_window(VFIOContainer *container,
> >> + hwaddr offset_within_address_space)
> >> +{
> >> + struct vfio_iommu_spapr_tce_remove remove = {
> >> + .argsz = sizeof(remove),
> >> + .start_addr = offset_within_address_space,
> >> + };
> >> + int ret;
> >> +
> >> + ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_REMOVE, &remove);
> >> + if (ret) {
> >> + error_report("Failed to remove window at %"PRIx64,
> >> + remove.start_addr);
> >> + return -errno;
> >> + }
> >> +
> >> + return 0;
> >> +}
> >> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> >> index c76ddc4..7e80382 100644
> >> --- a/include/hw/vfio/vfio-common.h
> >> +++ b/include/hw/vfio/vfio-common.h
> >> @@ -167,4 +167,10 @@ int vfio_get_dev_region_info(VFIODevice *vbasedev,
> >> uint32_t type,
> >> #endif
> >> extern const MemoryListener vfio_prereg_listener;
> >>
> >> +int vfio_spapr_create_window(VFIOContainer *container,
> >> + MemoryRegionSection *section,
> >> + hwaddr *pgsize);
> >> +int vfio_spapr_remove_window(VFIOContainer *container,
> >> + hwaddr offset_within_address_space);
> >> +
> >> #endif /* !HW_VFIO_VFIO_COMMON_H */
> >> diff --git a/trace-events b/trace-events
> >> index ddb8676..ec32c20 100644
> >> --- a/trace-events
> >> +++ b/trace-events
> >> @@ -1768,6 +1768,8 @@ vfio_region_sparse_mmap_entry(int i, unsigned long
> >> start, unsigned long end) "sp
> >> vfio_get_dev_region(const char *name, int index, uint32_t type, uint32_t
> >> subtype) "%s index %d, %08x/%0x8"
> >> vfio_ram_register(uint64_t va, uint64_t size, int ret) "va=%"PRIx64"
> >> size=%"PRIx64" ret=%d"
> >> vfio_ram_unregister(uint64_t va, uint64_t size, int ret) "va=%"PRIx64"
> >> size=%"PRIx64" ret=%d"
> >> +vfio_spapr_create_window(int ps, uint64_t ws, uint64_t off)
> >> "pageshift=0x%x winsize=0x%"PRIx64" offset=0x%"PRIx64
> >> +vfio_spapr_remove_window(uint64_t off) "offset=%"PRIx64
> >>
> >> # hw/vfio/platform.c
> >> vfio_platform_base_device_init(char *name, int groupid) "%s belongs to
> >> group #%d"
> >
>
>
--
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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