On Mon, 2015-07-06 at 12:11 +1000, Alexey Kardashevskiy wrote:
> This makes use of the new "memory registering" feature. The idea is
> to provide the userspace ability to notify the host kernel about pages
> which are going to be used for DMA. Having this information, the host
> kernel can pin them all once per user process, do locked pages
> accounting (once) and not spent time on doing that in real time with
> possible failures which cannot be handled nicely in some cases.
>
> This adds a guest RAM memory listener which notifies a VFIO container
> about memory which needs to be pinned/unpinned. VFIO MMIO regions
> (i.e. "skip dump" regions) are skipped.
>
> The feature is only enabled for SPAPR IOMMU v2. The host kernel changes
> are required. Since v2 does not need/support VFIO_IOMMU_ENABLE, this does
> not call it when v2 is detected and enabled.
>
> This does not change the guest visible interface.
>
> Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
> Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
> ---
> Changes:
> v9:
> * since there is no more SPAPR-specific data in container::iommu_data,
> the memory preregistration fields are common and potentially can be used
> by other architectures
>
> v7:
> * in vfio_spapr_ram_listener_region_del(), do unref() after ioctl()
> * s'ramlistener'register_listener'
>
> v6:
> * fixed commit log (s/guest/userspace/), added note about no guest visible
> change
> * fixed error checking if ram registration failed
> * added alignment check for section->offset_within_region
>
> v5:
> * simplified the patch
> * added trace points
> * added round_up() for the size
> * SPAPR IOMMU v2 used
> ---
> hw/vfio/common.c | 109
> ++++++++++++++++++++++++++++++++++++++----
> include/hw/vfio/vfio-common.h | 3 ++
> trace-events | 1 +
> 3 files changed, 104 insertions(+), 9 deletions(-)
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 8eacfd7..0c7ba8c 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -488,6 +488,76 @@ static void vfio_listener_release(VFIOContainer
> *container)
> memory_listener_unregister(&container->iommu_data.type1.listener);
> }
>
> +static void vfio_ram_do_region(VFIOContainer *container,
> + MemoryRegionSection *section, unsigned long
> req)
> +{
> + int ret;
> + struct vfio_iommu_spapr_register_memory reg = { .argsz = sizeof(reg) };
This function is not as general as the name would imply, it's spapr
specific due to this. How about vfio_spapr_register_memory() with a
bool parameter toggling register vs unregister so we're not passing an
arbitrary ioctl number?
> +
> + if (!memory_region_is_ram(section->mr) ||
> + memory_region_is_skip_dump(section->mr)) {
> + return;
> + }
> +
> + if (unlikely((section->offset_within_region & (getpagesize() - 1)))) {
s/getpagesize()/qemu_real_host_page_size/?
> + error_report("%s received unaligned region", __func__);
> + return;
> + }
> +
> + reg.vaddr = (__u64) memory_region_get_ram_ptr(section->mr) +
> + section->offset_within_region;
> + reg.size = ROUND_UP(int128_get64(section->size), TARGET_PAGE_SIZE);
> +
> + ret = ioctl(container->fd, req, ®);
> + trace_vfio_ram_register(_IOC_NR(req) - VFIO_BASE, reg.vaddr, reg.size,
> + ret ? -errno : 0);
> + if (!ret) {
> + return;
> + }
> +
> + /*
> + * On the initfn path, store the first error in the container so we
> + * can gracefully fail. Runtime, there's not much we can do other
> + * than throw a hardware error.
> + */
> + if (!container->iommu_data.ram_reg_initialized) {
> + if (!container->iommu_data.ram_reg_error) {
> + container->iommu_data.ram_reg_error = -errno;
> + }
> + } else {
> + hw_error("vfio: RAM registering failed, unable to continue");
> + }
I'd rather see:
if (ret) {
if (!container...) {
...
} else {
...
}
}
Exiting early on success and otherwise falling into error handling is a
strange code flow.
> +}
> +
> +static void vfio_ram_listener_region_add(MemoryListener *listener,
> + MemoryRegionSection *section)
> +{
> + VFIOContainer *container = container_of(listener, VFIOContainer,
> + iommu_data.register_listener);
> + memory_region_ref(section->mr);
> + vfio_ram_do_region(container, section, VFIO_IOMMU_SPAPR_REGISTER_MEMORY);
vfio_spapr_register_memory(container, section, true);
> +}
> +
> +static void vfio_ram_listener_region_del(MemoryListener *listener,
> + MemoryRegionSection *section)
> +{
> + VFIOContainer *container = container_of(listener, VFIOContainer,
> + iommu_data.register_listener);
> + vfio_ram_do_region(container, section,
> VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY);
vfio_spapr_register_memory(container, section, false);
> + memory_region_unref(section->mr);
> +}
> +
> +static const MemoryListener vfio_ram_memory_listener = {
> + .region_add = vfio_ram_listener_region_add,
> + .region_del = vfio_ram_listener_region_del,
> +};
These are all spapr specific, please reflect that in the name;
vfio_spapr_v2_memory_listener, vfio_spapr_v2_listener_add/del.
Actually, can't we determine what type of IOMMU we have and make the
existing MemoryListener handle either type1 or spapr or spapr-v2?
> +
> +static void vfio_spapr_listener_release_v2(VFIOContainer *container)
> +{
> + memory_listener_unregister(&container->iommu_data.register_listener);
> + vfio_listener_release(container);
> +}
> +
> int vfio_mmap_region(Object *obj, VFIORegion *region,
> MemoryRegion *mem, MemoryRegion *submem,
> void **map, size_t size, off_t offset,
> @@ -698,14 +768,18 @@ static int vfio_connect_container(VFIOGroup *group,
> AddressSpace *as)
>
> container->iommu_data.type1.initialized = true;
>
> - } else if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_IOMMU)) {
> + } else if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_IOMMU) ||
> + ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_v2_IOMMU)) {
> + bool v2 = !!ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_v2_IOMMU);
> +
> ret = ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &fd);
> if (ret) {
> error_report("vfio: failed to set group container: %m");
> ret = -errno;
> goto free_container_exit;
> }
> - ret = ioctl(fd, VFIO_SET_IOMMU, VFIO_SPAPR_TCE_IOMMU);
> + ret = ioctl(fd, VFIO_SET_IOMMU,
> + v2 ? VFIO_SPAPR_TCE_v2_IOMMU : VFIO_SPAPR_TCE_IOMMU);
> if (ret) {
> error_report("vfio: failed to set iommu for container: %m");
> ret = -errno;
> @@ -717,19 +791,36 @@ static int vfio_connect_container(VFIOGroup *group,
> AddressSpace *as)
> * when container fd is closed so we do not call it explicitly
> * in this file.
> */
> - ret = ioctl(fd, VFIO_IOMMU_ENABLE);
> - if (ret) {
> - error_report("vfio: failed to enable container: %m");
> - ret = -errno;
> - goto free_container_exit;
> + if (!v2) {
> + ret = ioctl(fd, VFIO_IOMMU_ENABLE);
> + if (ret) {
> + error_report("vfio: failed to enable container: %m");
> + ret = -errno;
> + goto free_container_exit;
> + }
> }
>
> container->iommu_data.type1.listener = vfio_memory_listener;
> - container->iommu_data.release = vfio_listener_release;
> -
> memory_listener_register(&container->iommu_data.type1.listener,
> container->space->as);
>
> + if (!v2) {
> + container->iommu_data.release = vfio_listener_release;
> + } else {
> + container->iommu_data.release = vfio_spapr_listener_release_v2;
> + container->iommu_data.register_listener =
> + vfio_ram_memory_listener;
> +
> memory_listener_register(&container->iommu_data.register_listener,
> + &address_space_memory);
> +
> + if (container->iommu_data.ram_reg_error) {
> + error_report("vfio: RAM memory listener initialization
> failed for container");
> + goto listener_release_exit;
> + }
> +
> + container->iommu_data.ram_reg_initialized = true;
> + }
> +
> } else {
> error_report("vfio: No available IOMMU models");
> ret = -EINVAL;
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index 59a321d..b132248 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -79,6 +79,9 @@ typedef struct VFIOContainer {
> VFIOType1 type1;
> };
> void (*release)(struct VFIOContainer *);
> + MemoryListener register_listener;
> + int ram_reg_error;
> + bool ram_reg_initialized;
Isn't this exactly what the union above is for?
> } iommu_data;
> QLIST_HEAD(, VFIOGuestIOMMU) giommu_list;
> QLIST_HEAD(, VFIOGroup) group_list;
> diff --git a/trace-events b/trace-events
> index a994019..b300e94 100644
> --- a/trace-events
> +++ b/trace-events
> @@ -1584,6 +1584,7 @@ vfio_disconnect_container(int fd) "close
> container->fd=%d"
> vfio_put_group(int fd) "close group->fd=%d"
> vfio_get_device(const char * name, unsigned int flags, unsigned int
> num_regions, unsigned int num_irqs) "Device %s flags: %u, regions: %u, irqs:
> %u"
> vfio_put_base_device(int fd) "close vdev->fd=%d"
> +vfio_ram_register(int req, uint64_t va, uint64_t size, int ret) "req=%d
> va=%"PRIx64" size=%"PRIx64" ret=%d"
>
> # hw/vfio/platform.c
> vfio_platform_populate_regions(int region_index, unsigned long flag,
> unsigned long size, int fd, unsigned long offset) "- region %d flags = 0x%lx,
> size = 0x%lx, fd= %d, offset = 0x%lx"
