If a guest reboots during a running migration, changes to the hash page table are not necessarily updated on the destination. Opening a new file descriptor to the HTAB forces the migration handler to resend the entire table.
Signed-off-by: Samuel Mendoza-Jonas <sam...@au1.ibm.com> --- Changes in v3: Pointed out by David, htab_save_iterate could potentially try to read before htab_fd is open again. Leave opening the fd to the functions trying to read. Changes in v2: Forgot check on kvmppc_get_htab_fd return value hw/ppc/spapr.c | 25 +++++++++++++++++++++++++ include/hw/ppc/spapr.h | 1 + 2 files changed, 26 insertions(+) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index 3a6d26d..5b41318 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -997,6 +997,10 @@ static void spapr_reset_htab(sPAPREnvironment *spapr) /* Kernel handles htab, we don't need to allocate one */ spapr->htab_shift = shift; kvmppc_kern_htab = true; + + /* Check if we are overlapping a migration */ + if (spapr->htab_fd > 0) + spapr->need_reset = true; } else { if (!spapr->htab) { /* Allocate an htab if we don't yet have one */ @@ -1156,6 +1160,7 @@ static int htab_save_setup(QEMUFile *f, void *opaque) } else { assert(kvm_enabled()); + spapr->need_reset = false; spapr->htab_fd = kvmppc_get_htab_fd(false); if (spapr->htab_fd < 0) { fprintf(stderr, "Unable to open fd for reading hash table from KVM: %s\n", @@ -1309,6 +1314,16 @@ static int htab_save_iterate(QEMUFile *f, void *opaque) if (!spapr->htab) { assert(kvm_enabled()); + if (atomic_cmpxchg(&spapr->need_reset, true, false) == true) { + close(spapr->htab_fd); + spapr->htab_fd = kvmppc_get_htab_fd(false); + if (spapr->htab_fd < 0) { + fprintf(stderr, "Unable to open fd for reading hash table from KVM: %s\n", + strerror(errno)); + return -1; + } + } + rc = kvmppc_save_htab(f, spapr->htab_fd, MAX_KVM_BUF_SIZE, MAX_ITERATION_NS); if (rc < 0) { @@ -1340,6 +1355,16 @@ static int htab_save_complete(QEMUFile *f, void *opaque) assert(kvm_enabled()); + if (atomic_cmpxchg(&spapr->need_reset, true, false) == true) { + close(spapr->htab_fd); + spapr->htab_fd = kvmppc_get_htab_fd(false); + if (spapr->htab_fd < 0) { + fprintf(stderr, "Unable to open fd for reading hash table from KVM: %s\n", + strerror(errno)); + return -1; + } + } + rc = kvmppc_save_htab(f, spapr->htab_fd, MAX_KVM_BUF_SIZE, -1); if (rc < 0) { return rc; diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h index 0c2e3c5..9ab9827 100644 --- a/include/hw/ppc/spapr.h +++ b/include/hw/ppc/spapr.h @@ -71,6 +71,7 @@ typedef struct sPAPREnvironment { int htab_save_index; bool htab_first_pass; int htab_fd; + bool need_reset; /* state for Dynamic Reconfiguration Connectors */ sPAPRDrcEntry drc_table[SPAPR_DRC_TABLE_SIZE]; -- 1.9.3