From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60796) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b2736-0005Ki-Qj for qemu-devel@nongnu.org; Sun, 15 May 2016 21:10:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b2730-0004cP-Qa for qemu-devel@nongnu.org; Sun, 15 May 2016 21:10:19 -0400 Received: from mail-pf0-x242.google.com ([2607:f8b0:400e:c00::242]:34302) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b2730-0004bw-Gq for qemu-devel@nongnu.org; Sun, 15 May 2016 21:10:14 -0400 Received: by mail-pf0-x242.google.com with SMTP id 145so14284663pfz.1 for ; Sun, 15 May 2016 18:10:13 -0700 (PDT) References: <1462344751-28281-1-git-send-email-aik@ozlabs.ru> <1462344751-28281-15-git-send-email-aik@ozlabs.ru> <20160513162544.27e4f053@t450s.home> From: Alexey Kardashevskiy Message-ID: <748d24c7-467f-cf4d-9b27-908a9e074961@ozlabs.ru> Date: Mon, 16 May 2016 11:10:05 +1000 MIME-Version: 1.0 In-Reply-To: <20160513162544.27e4f053@t450s.home> Content-Type: text/plain; charset=koi8-r; format=flowed 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: Alex Williamson Cc: qemu-devel@nongnu.org, qemu-ppc@nongnu.org, Alexander Graf , David Gibson , Paolo Bonzini On 05/14/2016 08:25 AM, Alex Williamson wrote: > 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? If I remember correctly, David did have theories where this may be possible, not today with the existing code though. Could be assert() or abort(), what is better here? >> + 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"? Userspace address. > >> +{ >> + 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? Yes. >> + >> + 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? I wanted to keep a prefix in all functions, even if they are static, easier to grep. Bad idea? >> + 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" -- Alexey