From 6380b0a02fbdac253b8a98b300398319ab655237 Mon Sep 17 00:00:00 2001 From: "Maciej S. Szmigiero" Date: Tue, 15 Jul 2025 16:37:36 +0200 Subject: [PATCH] vfio/migration: Add x-migration-load-config-after-iter VFIO property MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This property allows configuring whether to start the config load only after all iterables were loaded, during non-iterables loading phase. Such interlocking is required for ARM64 due to this platform VFIO dependency on interrupt controller being loaded first. The property defaults to AUTO, which means ON for ARM, OFF for other platforms. Reviewed-by: Fabiano Rosas Reviewed-by: Avihai Horon Signed-off-by: Maciej S. Szmigiero Link: https://lore.kernel.org/qemu-devel/0e03c60dbc91f9a9ba2516929574df605b7dfcb4.1752589295.git.maciej.szmigiero@oracle.com Signed-off-by: Cédric Le Goater --- docs/devel/migration/vfio.rst | 6 +++ hw/core/machine.c | 1 + hw/vfio/helpers.c | 17 +++++++ hw/vfio/migration-multifd.c | 79 +++++++++++++++++++++++++++++++ hw/vfio/migration-multifd.h | 3 ++ hw/vfio/migration.c | 10 +++- hw/vfio/pci.c | 10 ++++ hw/vfio/vfio-helpers.h | 2 + hw/vfio/vfio-migration-internal.h | 1 + include/hw/vfio/vfio-device.h | 1 + 10 files changed, 129 insertions(+), 1 deletion(-) diff --git a/docs/devel/migration/vfio.rst b/docs/devel/migration/vfio.rst index 2d8e5ca9dd..dae3a98830 100644 --- a/docs/devel/migration/vfio.rst +++ b/docs/devel/migration/vfio.rst @@ -247,3 +247,9 @@ The multifd VFIO device state transfer is controlled by "x-migration-multifd-transfer" VFIO device property. This property defaults to AUTO, which means that VFIO device state transfer via multifd channels is attempted in configurations that otherwise support it. + +Some host platforms (like ARM64) require that VFIO device config is loaded only +after all iterables were loaded, during non-iterables loading phase. +Such interlocking is controlled by "x-migration-load-config-after-iter" VFIO +device property, which in its default setting (AUTO) does so only on platforms +that actually require it. diff --git a/hw/core/machine.c b/hw/core/machine.c index e869821b22..16640b700f 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -39,6 +39,7 @@ GlobalProperty hw_compat_10_0[] = { { "scsi-hd", "dpofua", "off" }, + { "vfio-pci", "x-migration-load-config-after-iter", "off" }, }; const size_t hw_compat_10_0_len = G_N_ELEMENTS(hw_compat_10_0); diff --git a/hw/vfio/helpers.c b/hw/vfio/helpers.c index 9a5f621545..23d13e5db5 100644 --- a/hw/vfio/helpers.c +++ b/hw/vfio/helpers.c @@ -209,3 +209,20 @@ retry: return info; } + +bool vfio_arch_wants_loading_config_after_iter(void) +{ + /* + * Starting the config load only after all iterables were loaded (during + * non-iterables loading phase) is required for ARM64 due to this platform + * VFIO dependency on interrupt controller being loaded first. + * + * See commit d329f5032e17 ("vfio: Move the saving of the config space to + * the right place in VFIO migration"). + */ +#if defined(TARGET_ARM) + return true; +#else + return false; +#endif +} diff --git a/hw/vfio/migration-multifd.c b/hw/vfio/migration-multifd.c index 55635486c8..e539befaa9 100644 --- a/hw/vfio/migration-multifd.c +++ b/hw/vfio/migration-multifd.c @@ -23,6 +23,7 @@ #include "migration-multifd.h" #include "vfio-migration-internal.h" #include "trace.h" +#include "vfio-helpers.h" #define VFIO_DEVICE_STATE_CONFIG_STATE (1) @@ -35,6 +36,18 @@ typedef struct VFIODeviceStatePacket { uint8_t data[0]; } QEMU_PACKED VFIODeviceStatePacket; +bool vfio_load_config_after_iter(VFIODevice *vbasedev) +{ + if (vbasedev->migration_load_config_after_iter == ON_OFF_AUTO_ON) { + return true; + } else if (vbasedev->migration_load_config_after_iter == ON_OFF_AUTO_OFF) { + return false; + } + + assert(vbasedev->migration_load_config_after_iter == ON_OFF_AUTO_AUTO); + return vfio_arch_wants_loading_config_after_iter(); +} + /* type safety */ typedef struct VFIOStateBuffers { GArray *array; @@ -50,6 +63,9 @@ typedef struct VFIOMultifd { bool load_bufs_thread_running; bool load_bufs_thread_want_exit; + bool load_bufs_iter_done; + QemuCond load_bufs_iter_done_cond; + VFIOStateBuffers load_bufs; QemuCond load_bufs_buffer_ready_cond; QemuCond load_bufs_thread_finished_cond; @@ -394,6 +410,22 @@ static bool vfio_load_bufs_thread(void *opaque, bool *should_quit, Error **errp) multifd->load_buf_idx++; } + if (vfio_load_config_after_iter(vbasedev)) { + while (!multifd->load_bufs_iter_done) { + qemu_cond_wait(&multifd->load_bufs_iter_done_cond, + &multifd->load_bufs_mutex); + + /* + * Need to re-check cancellation immediately after wait in case + * cond was signalled by vfio_load_cleanup_load_bufs_thread(). + */ + if (vfio_load_bufs_thread_want_exit(multifd, should_quit)) { + error_setg(errp, "operation cancelled"); + goto thread_exit; + } + } + } + if (!vfio_load_bufs_thread_load_config(vbasedev, errp)) { goto thread_exit; } @@ -413,6 +445,48 @@ thread_exit: return ret; } +int vfio_load_state_config_load_ready(VFIODevice *vbasedev) +{ + VFIOMigration *migration = vbasedev->migration; + VFIOMultifd *multifd = migration->multifd; + int ret = 0; + + if (!vfio_multifd_transfer_enabled(vbasedev)) { + error_report("%s: got DEV_CONFIG_LOAD_READY outside multifd transfer", + vbasedev->name); + return -EINVAL; + } + + if (!vfio_load_config_after_iter(vbasedev)) { + error_report("%s: got DEV_CONFIG_LOAD_READY but was disabled", + vbasedev->name); + return -EINVAL; + } + + assert(multifd); + + /* The lock order is load_bufs_mutex -> BQL so unlock BQL here first */ + bql_unlock(); + WITH_QEMU_LOCK_GUARD(&multifd->load_bufs_mutex) { + if (multifd->load_bufs_iter_done) { + /* Can't print error here as we're outside BQL */ + ret = -EINVAL; + break; + } + + multifd->load_bufs_iter_done = true; + qemu_cond_signal(&multifd->load_bufs_iter_done_cond); + } + bql_lock(); + + if (ret) { + error_report("%s: duplicate DEV_CONFIG_LOAD_READY", + vbasedev->name); + } + + return ret; +} + static VFIOMultifd *vfio_multifd_new(void) { VFIOMultifd *multifd = g_new(VFIOMultifd, 1); @@ -425,6 +499,9 @@ static VFIOMultifd *vfio_multifd_new(void) multifd->load_buf_idx_last = UINT32_MAX; qemu_cond_init(&multifd->load_bufs_buffer_ready_cond); + multifd->load_bufs_iter_done = false; + qemu_cond_init(&multifd->load_bufs_iter_done_cond); + multifd->load_bufs_thread_running = false; multifd->load_bufs_thread_want_exit = false; qemu_cond_init(&multifd->load_bufs_thread_finished_cond); @@ -448,6 +525,7 @@ static void vfio_load_cleanup_load_bufs_thread(VFIOMultifd *multifd) multifd->load_bufs_thread_want_exit = true; qemu_cond_signal(&multifd->load_bufs_buffer_ready_cond); + qemu_cond_signal(&multifd->load_bufs_iter_done_cond); qemu_cond_wait(&multifd->load_bufs_thread_finished_cond, &multifd->load_bufs_mutex); } @@ -460,6 +538,7 @@ static void vfio_multifd_free(VFIOMultifd *multifd) vfio_load_cleanup_load_bufs_thread(multifd); qemu_cond_destroy(&multifd->load_bufs_thread_finished_cond); + qemu_cond_destroy(&multifd->load_bufs_iter_done_cond); vfio_state_buffers_destroy(&multifd->load_bufs); qemu_cond_destroy(&multifd->load_bufs_buffer_ready_cond); qemu_mutex_destroy(&multifd->load_bufs_mutex); diff --git a/hw/vfio/migration-multifd.h b/hw/vfio/migration-multifd.h index ebf22a7997..82d2d3a1fd 100644 --- a/hw/vfio/migration-multifd.h +++ b/hw/vfio/migration-multifd.h @@ -20,9 +20,12 @@ void vfio_multifd_cleanup(VFIODevice *vbasedev); bool vfio_multifd_transfer_supported(void); bool vfio_multifd_transfer_enabled(VFIODevice *vbasedev); +bool vfio_load_config_after_iter(VFIODevice *vbasedev); bool vfio_multifd_load_state_buffer(void *opaque, char *data, size_t data_size, Error **errp); +int vfio_load_state_config_load_ready(VFIODevice *vbasedev); + void vfio_multifd_emit_dummy_eos(VFIODevice *vbasedev, QEMUFile *f); bool diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c index c329578eec..4c06e3db93 100644 --- a/hw/vfio/migration.c +++ b/hw/vfio/migration.c @@ -675,7 +675,11 @@ static void vfio_save_state(QEMUFile *f, void *opaque) int ret; if (vfio_multifd_transfer_enabled(vbasedev)) { - vfio_multifd_emit_dummy_eos(vbasedev, f); + if (vfio_load_config_after_iter(vbasedev)) { + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_CONFIG_LOAD_READY); + } else { + vfio_multifd_emit_dummy_eos(vbasedev, f); + } return; } @@ -784,6 +788,10 @@ static int vfio_load_state(QEMUFile *f, void *opaque, int version_id) return ret; } + case VFIO_MIG_FLAG_DEV_CONFIG_LOAD_READY: + { + return vfio_load_state_config_load_ready(vbasedev); + } default: error_report("%s: Unknown tag 0x%"PRIx64, vbasedev->name, data); return -EINVAL; diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index 910042c6c2..09acad002a 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -3642,6 +3642,9 @@ static const Property vfio_pci_dev_properties[] = { vbasedev.migration_multifd_transfer, vfio_pci_migration_multifd_transfer_prop, OnOffAuto, .set_default = true, .defval.i = ON_OFF_AUTO_AUTO), + DEFINE_PROP_ON_OFF_AUTO("x-migration-load-config-after-iter", VFIOPCIDevice, + vbasedev.migration_load_config_after_iter, + ON_OFF_AUTO_AUTO), DEFINE_PROP_BOOL("migration-events", VFIOPCIDevice, vbasedev.migration_events, false), DEFINE_PROP_BOOL("x-no-mmap", VFIOPCIDevice, vbasedev.no_mmap, false), @@ -3818,6 +3821,13 @@ static void vfio_pci_dev_class_init(ObjectClass *klass, const void *data) "x-migration-multifd-transfer", "Transfer this device state via " "multifd channels when live migrating it"); + object_class_property_set_description(klass, /* 10.1 */ + "x-migration-load-config-after-iter", + "Start the config load only after " + "all iterables were loaded (during " + "non-iterables loading phase) when " + "doing live migration of device state " + "via multifd channels"); } static const TypeInfo vfio_pci_dev_info = { diff --git a/hw/vfio/vfio-helpers.h b/hw/vfio/vfio-helpers.h index 54a327ffbc..ce31758080 100644 --- a/hw/vfio/vfio-helpers.h +++ b/hw/vfio/vfio-helpers.h @@ -32,4 +32,6 @@ struct vfio_device_info *vfio_get_device_info(int fd); int vfio_kvm_device_add_fd(int fd, Error **errp); int vfio_kvm_device_del_fd(int fd, Error **errp); +bool vfio_arch_wants_loading_config_after_iter(void); + #endif /* HW_VFIO_VFIO_HELPERS_H */ diff --git a/hw/vfio/vfio-migration-internal.h b/hw/vfio/vfio-migration-internal.h index a8b456b239..54141e27e6 100644 --- a/hw/vfio/vfio-migration-internal.h +++ b/hw/vfio/vfio-migration-internal.h @@ -32,6 +32,7 @@ #define VFIO_MIG_FLAG_DEV_SETUP_STATE (0xffffffffef100003ULL) #define VFIO_MIG_FLAG_DEV_DATA_STATE (0xffffffffef100004ULL) #define VFIO_MIG_FLAG_DEV_INIT_DATA_SENT (0xffffffffef100005ULL) +#define VFIO_MIG_FLAG_DEV_CONFIG_LOAD_READY (0xffffffffef100006ULL) typedef struct VFIODevice VFIODevice; typedef struct VFIOMultifd VFIOMultifd; diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h index 1901a35aa9..dac3fdce15 100644 --- a/include/hw/vfio/vfio-device.h +++ b/include/hw/vfio/vfio-device.h @@ -67,6 +67,7 @@ typedef struct VFIODevice { bool ram_block_discard_allowed; OnOffAuto enable_migration; OnOffAuto migration_multifd_transfer; + OnOffAuto migration_load_config_after_iter; bool migration_events; bool use_region_fds; VFIODeviceOps *ops; -- 2.47.2