From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43375) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b1LWp-0008Os-Ej for qemu-devel@nongnu.org; Fri, 13 May 2016 18:25:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b1LWk-0004Ye-Ap for qemu-devel@nongnu.org; Fri, 13 May 2016 18:25:51 -0400 Date: Fri, 13 May 2016 16:25:44 -0600 From: Alex Williamson Message-ID: <20160513162544.27e4f053@t450s.home> In-Reply-To: <1462344751-28281-15-git-send-email-aik@ozlabs.ru> References: <1462344751-28281-1-git-send-email-aik@ozlabs.ru> <1462344751-28281-15-git-send-email-aik@ozlabs.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH qemu v16 14/19] vfio: spapr: Add DMA memory preregistering (SPAPR IOMMU v2) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexey Kardashevskiy Cc: qemu-devel@nongnu.org, qemu-ppc@nongnu.org, Alexander Graf , David Gibson , Paolo Bonzini On Wed, 4 May 2016 16:52:26 +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 prereg memory listener which listens on address_space_memory > and notifies a VFIO container about memory which needs to be > pinned/unpinned. VFIO MMIO regions (i.e. "skip dump" regions) are skipped. > > As there is no per-IOMMU-type release() callback anymore, this stores > the IOMMU type in the container so vfio_listener_release() can determine > if it needs to unregister @prereg_listener. > > 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 enforces guest RAM blocks to be host page size aligned; however > this is not new as KVM already requires memory slots to be host page > size aligned. > > Signed-off-by: Alexey Kardashevskiy > --- > Changes: > v16: > * switched to 64bit math everywhere as there is no chance to see > region_add on RAM blocks even remotely close to 1<<64bytes. > > v15: > * banned unaligned sections > * added an vfio_prereg_gpa_to_ua() helper > > v14: > * s/free_container_exit/listener_release_exit/g > * added "if memory_region_is_iommu()" to vfio_prereg_listener_skipped_section > --- > hw/vfio/Makefile.objs | 1 + > hw/vfio/common.c | 38 +++++++++--- > hw/vfio/prereg.c | 137 ++++++++++++++++++++++++++++++++++++++++++ > include/hw/vfio/vfio-common.h | 4 ++ > trace-events | 2 + > 5 files changed, 172 insertions(+), 10 deletions(-) > create mode 100644 hw/vfio/prereg.c > > diff --git a/hw/vfio/Makefile.objs b/hw/vfio/Makefile.objs > index ceddbb8..5800e0e 100644 > --- a/hw/vfio/Makefile.objs > +++ b/hw/vfio/Makefile.objs > @@ -4,4 +4,5 @@ obj-$(CONFIG_PCI) += pci.o pci-quirks.o > obj-$(CONFIG_SOFTMMU) += platform.o > obj-$(CONFIG_SOFTMMU) += calxeda-xgmac.o > obj-$(CONFIG_SOFTMMU) += amd-xgbe.o > +obj-$(CONFIG_SOFTMMU) += prereg.o > endif > diff --git a/hw/vfio/common.c b/hw/vfio/common.c > index 2050040..496eb82 100644 > --- a/hw/vfio/common.c > +++ b/hw/vfio/common.c > @@ -501,6 +501,9 @@ static const MemoryListener vfio_memory_listener = { > static void vfio_listener_release(VFIOContainer *container) > { > memory_listener_unregister(&container->listener); > + if (container->iommu_type == VFIO_SPAPR_TCE_v2_IOMMU) { > + memory_listener_unregister(&container->prereg_listener); > + } > } > > int vfio_region_setup(Object *obj, VFIODevice *vbasedev, VFIORegion *region, > @@ -808,8 +811,8 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as) > goto free_container_exit; > } > > - ret = ioctl(fd, VFIO_SET_IOMMU, > - v2 ? VFIO_TYPE1v2_IOMMU : VFIO_TYPE1_IOMMU); > + container->iommu_type = v2 ? VFIO_TYPE1v2_IOMMU : VFIO_TYPE1_IOMMU; > + ret = ioctl(fd, VFIO_SET_IOMMU, container->iommu_type); > if (ret) { > error_report("vfio: failed to set iommu for container: %m"); > ret = -errno; > @@ -834,8 +837,10 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as) > if ((ret == 0) && (info.flags & VFIO_IOMMU_INFO_PGSIZES)) { > container->iova_pgsizes = info.iova_pgsizes; > } > - } 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)) { > struct vfio_iommu_spapr_tce_info info; > + bool v2 = !!ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_v2_IOMMU); > > ret = ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &fd); > if (ret) { > @@ -843,7 +848,9 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as) > ret = -errno; > goto free_container_exit; > } > - ret = ioctl(fd, VFIO_SET_IOMMU, VFIO_SPAPR_TCE_IOMMU); > + container->iommu_type = > + v2 ? VFIO_SPAPR_TCE_v2_IOMMU : VFIO_SPAPR_TCE_IOMMU; > + ret = ioctl(fd, VFIO_SET_IOMMU, container->iommu_type); > if (ret) { > error_report("vfio: failed to set iommu for container: %m"); > ret = -errno; > @@ -855,11 +862,22 @@ 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; > + } > + } else { > + container->prereg_listener = vfio_prereg_listener; > + > + memory_listener_register(&container->prereg_listener, > + &address_space_memory); > + if (container->error) { > + error_report("vfio: RAM memory listener initialization failed for container"); > + goto listener_release_exit; > + } > } > > /* > @@ -872,7 +890,7 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as) > if (ret) { > error_report("vfio: VFIO_IOMMU_SPAPR_TCE_GET_INFO failed: %m"); > ret = -errno; > - goto free_container_exit; > + goto listener_release_exit; > } > container->min_iova = info.dma32_window_start; > container->max_iova = container->min_iova + info.dma32_window_size - 1; > diff --git a/hw/vfio/prereg.c b/hw/vfio/prereg.c > new file mode 100644 > index 0000000..d0e4728 > --- /dev/null > +++ b/hw/vfio/prereg.c > @@ -0,0 +1,137 @@ > +/* > + * DMA memory preregistration > + * > + * Authors: > + * Alexey Kardashevskiy > + * > + * This work is licensed under the terms of the GNU GPL, version 2. See > + * the COPYING file in the top-level directory. > + */ > + > +#include "qemu/osdep.h" > +#include > +#include > + > +#include "hw/vfio/vfio-common.h" > +#include "hw/hw.h" > +#include "qemu/error-report.h" > +#include "trace.h" > + > +static bool vfio_prereg_listener_skipped_section(MemoryRegionSection *section) > +{ > + if (memory_region_is_iommu(section->mr)) { > + error_report("Cannot possibly preregister IOMMU memory"); What is a user supposed to do with this error_report()? Is it continue-able? How is it possible? What should they do differently? > + return true; > + } > + > + return !memory_region_is_ram(section->mr) || > + memory_region_is_skip_dump(section->mr); > +} > + > +static void *vfio_prereg_gpa_to_ua(MemoryRegionSection *section, hwaddr gpa) What's "ua"? > +{ > + return memory_region_get_ram_ptr(section->mr) + > + section->offset_within_region + > + (gpa - section->offset_within_address_space); > +} > + > +static void vfio_prereg_listener_region_add(MemoryListener *listener, > + MemoryRegionSection *section) > +{ > + VFIOContainer *container = container_of(listener, VFIOContainer, > + prereg_listener); > + const hwaddr gpa = section->offset_within_address_space; > + hwaddr end; > + int ret; > + hwaddr page_mask = qemu_real_host_page_mask; > + struct vfio_iommu_spapr_register_memory reg = { > + .argsz = sizeof(reg), > + .flags = 0, > + }; So we're just pretending that this spapr specific code is some sort of generic pre-registration interface? > + > + if (vfio_prereg_listener_skipped_section(section)) { > + trace_vfio_listener_region_add_skip( > + section->offset_within_address_space, > + section->offset_within_address_space + > + int128_get64(int128_sub(section->size, int128_one()))); > + return; > + } > + > + if (unlikely((section->offset_within_address_space & ~page_mask) || > + (section->offset_within_region & ~page_mask) || > + (int128_get64(section->size) & ~page_mask))) { > + error_report("%s received unaligned region", __func__); > + return; > + } > + > + end = section->offset_within_address_space + int128_get64(section->size); > + g_assert(gpa < end); > + > + memory_region_ref(section->mr); > + > + reg.vaddr = (__u64) vfio_prereg_gpa_to_ua(section, gpa); Hmm, why wasn't that simply gpa_to_vaddr? > + reg.size = end - gpa; > + > + ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_REGISTER_MEMORY, ®); > + trace_vfio_ram_register(reg.vaddr, reg.size, ret ? -errno : 0); > + if (ret) { > + /* > + * 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->initialized) { > + if (!container->error) { > + container->error = ret; > + } > + } else { > + hw_error("vfio: Memory registering failed, unable to continue"); > + } > + } > +} > + > +static void vfio_prereg_listener_region_del(MemoryListener *listener, > + MemoryRegionSection *section) > +{ > + VFIOContainer *container = container_of(listener, VFIOContainer, > + prereg_listener); > + const hwaddr gpa = section->offset_within_address_space; > + hwaddr end; > + int ret; > + hwaddr page_mask = qemu_real_host_page_mask; > + struct vfio_iommu_spapr_register_memory reg = { > + .argsz = sizeof(reg), > + .flags = 0, > + }; > + > + if (vfio_prereg_listener_skipped_section(section)) { > + trace_vfio_listener_region_del_skip( > + section->offset_within_address_space, > + section->offset_within_address_space + > + int128_get64(int128_sub(section->size, int128_one()))); > + return; > + } > + > + if (unlikely((section->offset_within_address_space & ~page_mask) || > + (section->offset_within_region & ~page_mask) || > + (int128_get64(section->size) & ~page_mask))) { > + error_report("%s received unaligned region", __func__); > + return; > + } > + > + end = section->offset_within_address_space + int128_get64(section->size); > + if (gpa >= end) { > + return; > + } > + > + reg.vaddr = (__u64) vfio_prereg_gpa_to_ua(section, gpa); > + reg.size = end - gpa; > + > + ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY, ®); > + trace_vfio_ram_unregister(reg.vaddr, reg.size, ret ? -errno : 0); > +} > + > +const MemoryListener vfio_prereg_listener = { > + .region_add = vfio_prereg_listener_region_add, > + .region_del = vfio_prereg_listener_region_del, > +}; > diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h > index c9b6622..c72e45a 100644 > --- a/include/hw/vfio/vfio-common.h > +++ b/include/hw/vfio/vfio-common.h > @@ -73,6 +73,8 @@ typedef struct VFIOContainer { > VFIOAddressSpace *space; > int fd; /* /dev/vfio/vfio, empowered by the attached groups */ > MemoryListener listener; > + MemoryListener prereg_listener; > + unsigned iommu_type; > int error; > bool initialized; > /* > @@ -156,4 +158,6 @@ extern QLIST_HEAD(vfio_as_head, VFIOAddressSpace) vfio_address_spaces; > int vfio_get_region_info(VFIODevice *vbasedev, int index, > struct vfio_region_info **info); > #endif > +extern const MemoryListener vfio_prereg_listener; > + > #endif /* !HW_VFIO_VFIO_COMMON_H */ > diff --git a/trace-events b/trace-events > index dd50005..d0d8615 100644 > --- a/trace-events > +++ b/trace-events > @@ -1737,6 +1737,8 @@ vfio_region_mmap(const char *name, unsigned long offset, unsigned long end) "Reg > vfio_region_exit(const char *name, int index) "Device %s, region %d" > vfio_region_finalize(const char *name, int index) "Device %s, region %d" > vfio_region_mmaps_set_enabled(const char *name, bool enabled) "Region %s mmaps enabled: %d" > +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" > > # hw/vfio/platform.c > vfio_platform_base_device_init(char *name, int groupid) "%s belongs to group #%d"