From 5f1f1902f8e4020f27b4e35631a38c4e68d9be54 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 26 Jun 2020 09:22:35 +0200 Subject: [PATCH] migration/rdma: Use ram_block_discard_disable() RDMA will pin all guest memory (as documented in docs/rdma.txt). We want to disable RAM block discards - however, to keep it simple use ram_block_discard_is_required() instead of inhibiting. Note: It is not sufficient to limit disabling to pin_all. Even when only conditionally pinning 1 MB chunks, as soon as one page within such a chunk was discarded and one page not, the discarded pages will be pinned as well. Reviewed-by: Dr. David Alan Gilbert Cc: "Michael S. Tsirkin" Cc: Juan Quintela Cc: "Dr. David Alan Gilbert" Signed-off-by: David Hildenbrand Message-Id: <20200626072248.78761-9-david@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- migration/rdma.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/migration/rdma.c b/migration/rdma.c index ec45d33ba3..bbe6f36627 100644 --- a/migration/rdma.c +++ b/migration/rdma.c @@ -29,6 +29,7 @@ #include "qemu/sockets.h" #include "qemu/bitmap.h" #include "qemu/coroutine.h" +#include "exec/memory.h" #include #include #include @@ -4017,8 +4018,14 @@ void rdma_start_incoming_migration(const char *host_port, Error **errp) Error *local_err = NULL; trace_rdma_start_incoming_migration(); - rdma = qemu_rdma_data_init(host_port, &local_err); + /* Avoid ram_block_discard_disable(), cannot change during migration. */ + if (ram_block_discard_is_required()) { + error_setg(errp, "RDMA: cannot disable RAM discard"); + return; + } + + rdma = qemu_rdma_data_init(host_port, &local_err); if (rdma == NULL) { goto err; } @@ -4067,10 +4074,17 @@ void rdma_start_outgoing_migration(void *opaque, const char *host_port, Error **errp) { MigrationState *s = opaque; - RDMAContext *rdma = qemu_rdma_data_init(host_port, errp); RDMAContext *rdma_return_path = NULL; + RDMAContext *rdma; int ret = 0; + /* Avoid ram_block_discard_disable(), cannot change during migration. */ + if (ram_block_discard_is_required()) { + error_setg(errp, "RDMA: cannot disable RAM discard"); + return; + } + + rdma = qemu_rdma_data_init(host_port, errp); if (rdma == NULL) { goto err; }