On 30/5/25 18:32, Chenyi Qiang wrote:
A new field, attributes, was introduced in RAMBlock to link to a RamBlockAttributes object, which centralizes all guest_memfd related information (such as fd and shared bitmap) within a RAMBlock. Create and initialize the RamBlockAttributes object upon ram_block_add(). Meanwhile, register the object in the target RAMBlock's MemoryRegion. After that, guest_memfd-backed RAMBlock is associated with the RamDiscardManager interface, and the users can execute RamDiscardManager specific handling. For example, VFIO will register the RamDiscardListener and get notifications when the state_change() helper invokes. As coordinate discarding of RAM with guest_memfd is now supported, only block uncoordinated discard. Signed-off-by: Chenyi Qiang <chenyi.qi...@intel.com>
Tested-by: Alexey Kardashevskiy <a...@amd.com> Reviewed-by: Alexey Kardashevskiy <a...@amd.com>
--- Changes in v6: - Squash the unblocking of cooridnate discard into this commit. - Remove the checks in migration path. Changes in v5: - Revert to use RamDiscardManager interface. - Move the object_new() into the ram_block_attribute_create() helper. - Add some check in migration path. Changes in v4: - Remove the replay operations for attribute changes which will be handled in a listener in following patches. - Add some comment in the error path of realize() to remind the future development of the unified error path. Changes in v3: - Use ram_discard_manager_reply_populated/discarded() to set the memory attribute and add the undo support if state_change() failed. - Didn't add Reviewed-by from Alexey due to the new changes in this commit. --- accel/kvm/kvm-all.c | 9 +++++++++ include/system/ramblock.h | 1 + system/physmem.c | 18 ++++++++++++++++-- 3 files changed, 26 insertions(+), 2 deletions(-) diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index 51526d301b..3b390bbb09 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -3089,6 +3089,15 @@ int kvm_convert_memory(hwaddr start, hwaddr size, bool to_private) addr = memory_region_get_ram_ptr(mr) + section.offset_within_region; rb = qemu_ram_block_from_host(addr, false, &offset);+ ret = ram_block_attributes_state_change(RAM_BLOCK_ATTRIBUTES(mr->rdm),+ offset, size, to_private); + if (ret) { + error_report("Failed to notify the listener the state change of " + "(0x%"HWADDR_PRIx" + 0x%"HWADDR_PRIx") to %s", + start, size, to_private ? "private" : "shared"); + goto out_unref; + } + if (to_private) { if (rb->page_size != qemu_real_host_page_size()) { /* diff --git a/include/system/ramblock.h b/include/system/ramblock.h index 1bab9e2dac..87e847e184 100644 --- a/include/system/ramblock.h +++ b/include/system/ramblock.h @@ -46,6 +46,7 @@ struct RAMBlock { int fd; uint64_t fd_offset; int guest_memfd; + RamBlockAttributes *attributes; size_t page_size; /* dirty bitmap used during migration */ unsigned long *bmap; diff --git a/system/physmem.c b/system/physmem.c index a8a9ca309e..1f1217fa0a 100644 --- a/system/physmem.c +++ b/system/physmem.c @@ -1916,7 +1916,7 @@ static void ram_block_add(RAMBlock *new_block, Error **errp) } assert(new_block->guest_memfd < 0);- ret = ram_block_discard_require(true);+ ret = ram_block_coordinated_discard_require(true); if (ret < 0) { error_setg_errno(errp, -ret, "cannot set up private guest memory: discard currently blocked"); @@ -1931,6 +1931,19 @@ static void ram_block_add(RAMBlock *new_block, Error **errp) goto out_free; }+ new_block->attributes = ram_block_attributes_create(new_block);+ if (!new_block->attributes) { + error_setg(errp, "Failed to create ram block attribute"); + /* + * The error path could be unified if the rest of ram_block_add() + * ever develops a need to check for errors. + */ + close(new_block->guest_memfd); + ram_block_coordinated_discard_require(false); + qemu_mutex_unlock_ramlist(); + goto out_free; + } + /* * Add a specific guest_memfd blocker if a generic one would not be * added by ram_block_add_cpr_blocker. @@ -2287,8 +2300,9 @@ static void reclaim_ramblock(RAMBlock *block) }if (block->guest_memfd >= 0) {+ ram_block_attributes_destroy(block->attributes); close(block->guest_memfd); - ram_block_discard_require(false); + ram_block_coordinated_discard_require(false); }g_free(block);
-- Alexey
