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Mon, 04 May 2020 16:18:15 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Mon, 04 May 2020 16:18:27 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Mon, 04 May 2020 16:18:27 -0700 Received: from DRHQMAIL107.nvidia.com (10.27.9.16) by HQMAIL109.nvidia.com (172.20.187.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 4 May 2020 23:18:27 +0000 Received: from [10.40.101.152] (10.124.1.5) by DRHQMAIL107.nvidia.com (10.27.9.16) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 4 May 2020 23:18:18 +0000 Subject: Re: [PATCH v16 QEMU 09/16] vfio: Add save state functions to SaveVMHandlers To: Alex Williamson References: <1585084154-29461-1-git-send-email-kwankhede@nvidia.com> <1585084154-29461-10-git-send-email-kwankhede@nvidia.com> <20200325160311.265ca037@w520.home> X-Nvconfidentiality: public From: Kirti Wankhede Message-ID: Date: Tue, 5 May 2020 04:48:14 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; 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envelope-from=kwankhede@nvidia.com; helo=hqnvemgate26.nvidia.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/04 19:18:18 X-ACL-Warn: Detected OS = Windows 7 or 8 [fuzzy] X-Spam_score_int: -70 X-Spam_score: -7.1 X-Spam_bar: ------- X-Spam_report: (-7.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Zhengxiao.zx@Alibaba-inc.com, kevin.tian@intel.com, yi.l.liu@intel.com, cjia@nvidia.com, eskultet@redhat.com, ziye.yang@intel.com, qemu-devel@nongnu.org, cohuck@redhat.com, shuangtai.tst@alibaba-inc.com, dgilbert@redhat.com, zhi.a.wang@intel.com, mlevitsk@redhat.com, pasic@linux.ibm.com, aik@ozlabs.ru, eauger@redhat.com, felipe@nutanix.com, jonathan.davies@nutanix.com, yan.y.zhao@intel.com, changpeng.liu@intel.com, Ken.Xue@amd.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/26/2020 3:33 AM, Alex Williamson wrote: > On Wed, 25 Mar 2020 02:39:07 +0530 > Kirti Wankhede wrote: > >> Added .save_live_pending, .save_live_iterate and .save_live_complete_precopy >> functions. These functions handles pre-copy and stop-and-copy phase. >> >> In _SAVING|_RUNNING device state or pre-copy phase: >> - read pending_bytes. If pending_bytes > 0, go through below steps. >> - read data_offset - indicates kernel driver to write data to staging >> buffer. >> - read data_size - amount of data in bytes written by vendor driver in >> migration region. >> - read data_size bytes of data from data_offset in the migration region. >> - Write data packet to file stream as below: >> {VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data, >> VFIO_MIG_FLAG_END_OF_STATE } >> >> In _SAVING device state or stop-and-copy phase >> a. read config space of device and save to migration file stream. This >> doesn't need to be from vendor driver. Any other special config state >> from driver can be saved as data in following iteration. >> b. read pending_bytes. If pending_bytes > 0, go through below steps. >> c. read data_offset - indicates kernel driver to write data to staging >> buffer. >> d. read data_size - amount of data in bytes written by vendor driver in >> migration region. >> e. read data_size bytes of data from data_offset in the migration region. >> f. Write data packet as below: >> {VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data} >> g. iterate through steps b to f while (pending_bytes > 0) >> h. Write {VFIO_MIG_FLAG_END_OF_STATE} >> >> When data region is mapped, its user's responsibility to read data from >> data_offset of data_size before moving to next steps. >> >> Signed-off-by: Kirti Wankhede >> Reviewed-by: Neo Jia >> --- >> hw/vfio/migration.c | 245 +++++++++++++++++++++++++++++++++++++++++- >> hw/vfio/trace-events | 6 ++ >> include/hw/vfio/vfio-common.h | 1 + >> 3 files changed, 251 insertions(+), 1 deletion(-) >> >> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c >> index 033f76526e49..ecbeed5182c2 100644 >> --- a/hw/vfio/migration.c >> +++ b/hw/vfio/migration.c >> @@ -138,6 +138,137 @@ static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t mask, >> return 0; >> } >> >> +static void *find_data_region(VFIORegion *region, >> + uint64_t data_offset, >> + uint64_t data_size) >> +{ >> + void *ptr = NULL; >> + int i; >> + >> + for (i = 0; i < region->nr_mmaps; i++) { >> + if ((data_offset >= region->mmaps[i].offset) && >> + (data_offset < region->mmaps[i].offset + region->mmaps[i].size) && >> + (data_size <= region->mmaps[i].size)) { > > (data_offset - region->mmaps[i].offset) can be non-zero, so this test > is invalid. Additionally the uapi does not require that a give data > chunk fits exclusively within an mmap'd area, it may overlap one or > more mmap'd sections of the region, possibly with non-mmap'd areas > included. > What's the advantage of having mmap and non-mmap overlapped regions? Isn't it better to have data section either mapped or trapped? >> + ptr = region->mmaps[i].mmap + (data_offset - >> + region->mmaps[i].offset); >> + break; >> + } >> + } >> + return ptr; >> +} >> + >> +static int vfio_save_buffer(QEMUFile *f, VFIODevice *vbasedev) >> +{ >> + VFIOMigration *migration = vbasedev->migration; >> + VFIORegion *region = &migration->region; >> + uint64_t data_offset = 0, data_size = 0; >> + int ret; >> + >> + ret = pread(vbasedev->fd, &data_offset, sizeof(data_offset), >> + region->fd_offset + offsetof(struct vfio_device_migration_info, >> + data_offset)); >> + if (ret != sizeof(data_offset)) { >> + error_report("%s: Failed to get migration buffer data offset %d", >> + vbasedev->name, ret); >> + return -EINVAL; >> + } >> + >> + ret = pread(vbasedev->fd, &data_size, sizeof(data_size), >> + region->fd_offset + offsetof(struct vfio_device_migration_info, >> + data_size)); >> + if (ret != sizeof(data_size)) { >> + error_report("%s: Failed to get migration buffer data size %d", >> + vbasedev->name, ret); >> + return -EINVAL; >> + } >> + >> + if (data_size > 0) { >> + void *buf = NULL; >> + bool buffer_mmaped; >> + >> + if (region->mmaps) { >> + buf = find_data_region(region, data_offset, data_size); >> + } >> + >> + buffer_mmaped = (buf != NULL) ? true : false; > > The ternary is unnecessary, "? true : false" is redundant. > Removing it. >> + >> + if (!buffer_mmaped) { >> + buf = g_try_malloc0(data_size); > > Why do we need zero'd memory? > Zeroed memory not required, removing 0 >> + if (!buf) { >> + error_report("%s: Error allocating buffer ", __func__); >> + return -ENOMEM; >> + } >> + >> + ret = pread(vbasedev->fd, buf, data_size, >> + region->fd_offset + data_offset); >> + if (ret != data_size) { >> + error_report("%s: Failed to get migration data %d", >> + vbasedev->name, ret); >> + g_free(buf); >> + return -EINVAL; >> + } >> + } >> + >> + qemu_put_be64(f, data_size); >> + qemu_put_buffer(f, buf, data_size); > > This can segfault when mmap'd given the above assumptions about size > and layout. > >> + >> + if (!buffer_mmaped) { >> + g_free(buf); >> + } >> + } else { >> + qemu_put_be64(f, data_size); > > We insert a zero? Couldn't we add the section header and end here and > skip it entirely? > This is used during resuming, data_size 0 indicates end of data. >> + } >> + >> + trace_vfio_save_buffer(vbasedev->name, data_offset, data_size, >> + migration->pending_bytes); >> + >> + ret = qemu_file_get_error(f); >> + if (ret) { >> + return ret; >> + } >> + >> + return data_size; >> +} >> + >> +static int vfio_update_pending(VFIODevice *vbasedev) >> +{ >> + VFIOMigration *migration = vbasedev->migration; >> + VFIORegion *region = &migration->region; >> + uint64_t pending_bytes = 0; >> + int ret; >> + >> + ret = pread(vbasedev->fd, &pending_bytes, sizeof(pending_bytes), >> + region->fd_offset + offsetof(struct vfio_device_migration_info, >> + pending_bytes)); >> + if ((ret < 0) || (ret != sizeof(pending_bytes))) { >> + error_report("%s: Failed to get pending bytes %d", >> + vbasedev->name, ret); >> + migration->pending_bytes = 0; >> + return (ret < 0) ? ret : -EINVAL; >> + } >> + >> + migration->pending_bytes = pending_bytes; >> + trace_vfio_update_pending(vbasedev->name, pending_bytes); >> + return 0; >> +} >> + >> +static int vfio_save_device_config_state(QEMUFile *f, void *opaque) >> +{ >> + VFIODevice *vbasedev = opaque; >> + >> + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_CONFIG_STATE); >> + >> + if (vbasedev->ops && vbasedev->ops->vfio_save_config) { >> + vbasedev->ops->vfio_save_config(vbasedev, f); >> + } >> + >> + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE); >> + >> + trace_vfio_save_device_config_state(vbasedev->name); >> + >> + return qemu_file_get_error(f); >> +} >> + >> /* ---------------------------------------------------------------------- */ >> >> static int vfio_save_setup(QEMUFile *f, void *opaque) >> @@ -154,7 +285,7 @@ static int vfio_save_setup(QEMUFile *f, void *opaque) >> qemu_mutex_unlock_iothread(); >> if (ret) { >> error_report("%s: Failed to mmap VFIO migration region %d: %s", >> - vbasedev->name, migration->region.index, >> + vbasedev->name, migration->region.nr, >> strerror(-ret)); >> return ret; >> } >> @@ -194,9 +325,121 @@ static void vfio_save_cleanup(void *opaque) >> trace_vfio_save_cleanup(vbasedev->name); >> } >> >> +static void vfio_save_pending(QEMUFile *f, void *opaque, >> + uint64_t threshold_size, >> + uint64_t *res_precopy_only, >> + uint64_t *res_compatible, >> + uint64_t *res_postcopy_only) >> +{ >> + VFIODevice *vbasedev = opaque; >> + VFIOMigration *migration = vbasedev->migration; >> + int ret; >> + >> + ret = vfio_update_pending(vbasedev); >> + if (ret) { >> + return; >> + } >> + >> + *res_precopy_only += migration->pending_bytes; >> + >> + trace_vfio_save_pending(vbasedev->name, *res_precopy_only, >> + *res_postcopy_only, *res_compatible); >> +} >> + >> +static int vfio_save_iterate(QEMUFile *f, void *opaque) >> +{ >> + VFIODevice *vbasedev = opaque; >> + int ret, data_size; >> + >> + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE); >> + >> + data_size = vfio_save_buffer(f, vbasedev); >> + >> + if (data_size < 0) { >> + error_report("%s: vfio_save_buffer failed %s", vbasedev->name, >> + strerror(errno)); >> + return data_size; >> + } >> + >> + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE); >> + >> + ret = qemu_file_get_error(f); >> + if (ret) { >> + return ret; >> + } >> + >> + trace_vfio_save_iterate(vbasedev->name, data_size); >> + if (data_size == 0) { >> + /* indicates data finished, goto complete phase */ >> + return 1; > > But it's pending_bytes not data_size that indicates we're done. How do > we get away with ignoring pending_bytes for the save_live_iterate phase? > This is requirement mentioned above qemu_savevm_state_iterate() which calls .save_live_iterate. /* * this function has three return values: * negative: there was one error, and we have -errno. * 0 : We haven't finished, caller have to go again * 1 : We have finished, we can go to complete phase */ int qemu_savevm_state_iterate(QEMUFile *f, bool postcopy) This is to serialize savevm_state.handlers (or in other words devices). Thanks, Kirti >> + } >> + >> + return 0; >> +} >> + >> +static int vfio_save_complete_precopy(QEMUFile *f, void *opaque) >> +{ >> + VFIODevice *vbasedev = opaque; >> + VFIOMigration *migration = vbasedev->migration; >> + int ret; >> + >> + ret = vfio_migration_set_state(vbasedev, ~VFIO_DEVICE_STATE_RUNNING, >> + VFIO_DEVICE_STATE_SAVING); >> + if (ret) { >> + error_report("%s: Failed to set state STOP and SAVING", >> + vbasedev->name); >> + return ret; >> + } >> + >> + ret = vfio_save_device_config_state(f, opaque); >> + if (ret) { >> + return ret; >> + } >> + >> + ret = vfio_update_pending(vbasedev); >> + if (ret) { >> + return ret; >> + } >> + >> + while (migration->pending_bytes > 0) { >> + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE); >> + ret = vfio_save_buffer(f, vbasedev); >> + if (ret < 0) { >> + error_report("%s: Failed to save buffer", vbasedev->name); >> + return ret; >> + } else if (ret == 0) { >> + break; >> + } >> + >> + ret = vfio_update_pending(vbasedev); >> + if (ret) { >> + return ret; >> + } >> + } >> + >> + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE); >> + >> + ret = qemu_file_get_error(f); >> + if (ret) { >> + return ret; >> + } >> + >> + ret = vfio_migration_set_state(vbasedev, ~VFIO_DEVICE_STATE_SAVING, 0); >> + if (ret) { >> + error_report("%s: Failed to set state STOPPED", vbasedev->name); >> + return ret; >> + } >> + >> + trace_vfio_save_complete_precopy(vbasedev->name); >> + return ret; >> +} >> + >> static SaveVMHandlers savevm_vfio_handlers = { >> .save_setup = vfio_save_setup, >> .save_cleanup = vfio_save_cleanup, >> + .save_live_pending = vfio_save_pending, >> + .save_live_iterate = vfio_save_iterate, >> + .save_live_complete_precopy = vfio_save_complete_precopy, >> }; >> >> /* ---------------------------------------------------------------------- */ >> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events >> index 4bb43f18f315..bdf40ba368c7 100644 >> --- a/hw/vfio/trace-events >> +++ b/hw/vfio/trace-events >> @@ -151,3 +151,9 @@ vfio_vmstate_change(char *name, int running, const char *reason, uint32_t dev_st >> vfio_migration_state_notifier(char *name, int state) " (%s) state %d" >> vfio_save_setup(char *name) " (%s)" >> vfio_save_cleanup(char *name) " (%s)" >> +vfio_save_buffer(char *name, uint64_t data_offset, uint64_t data_size, uint64_t pending) " (%s) Offset 0x%"PRIx64" size 0x%"PRIx64" pending 0x%"PRIx64 >> +vfio_update_pending(char *name, uint64_t pending) " (%s) pending 0x%"PRIx64 >> +vfio_save_device_config_state(char *name) " (%s)" >> +vfio_save_pending(char *name, uint64_t precopy, uint64_t postcopy, uint64_t compatible) " (%s) precopy 0x%"PRIx64" postcopy 0x%"PRIx64" compatible 0x%"PRIx64 >> +vfio_save_iterate(char *name, int data_size) " (%s) data_size %d" >> +vfio_save_complete_precopy(char *name) " (%s)" >> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h >> index 28f55f66d019..c78033e4149d 100644 >> --- a/include/hw/vfio/vfio-common.h >> +++ b/include/hw/vfio/vfio-common.h >> @@ -60,6 +60,7 @@ typedef struct VFIORegion { >> >> typedef struct VFIOMigration { >> VFIORegion region; >> + uint64_t pending_bytes; >> } VFIOMigration; >> >> typedef struct VFIOAddressSpace { >