On 11/05/2014 05:17 PM, Samuel Mendoza-Jonas wrote:
> 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>
> ---
> hw/ppc/spapr.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
> include/hw/ppc/spapr.h | 2 ++
> 2 files changed, 49 insertions(+)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 0a2bfe6..1610c28 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -833,6 +833,13 @@ 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;
> +
> + /* Tell readers to update their file descriptor */
> + pthread_mutex_lock(&spapr->htab_mutex);
> + if (spapr->htab_fd > 0) {
s/>/>=/
htab_fd == 0 is correct.
> + spapr->htab_fd_stale = true;
> + }
> + pthread_mutex_unlock(&spapr->htab_mutex);
> } else {
> if (!spapr->htab) {
> /* Allocate an htab if we don't yet have one */
> @@ -850,6 +857,31 @@ static void spapr_reset_htab(sPAPREnvironment *spapr)
> }
> }
>
> +/* A guest reset will cause spapr->htab_fd to become stale if being used.
Multiline comment starts with /* and \n.
> + * Reopen the file descriptor to make sure the whole HTAB is properly read.
> + */
> +static int spapr_check_htab_fd(sPAPREnvironment *spapr)
> +{
> + int rc = 0;
> +
> + pthread_mutex_lock(&spapr->htab_mutex);
> +
> + if (spapr->htab_fd_stale) {
> + close(spapr->htab_fd);
> + spapr->htab_fd = kvmppc_get_htab_fd(false);
> + if (spapr->htab_fd < 0) {
> + error_report("Unable to open fd for reading hash table from KVM:
> "
> + "%s", strerror(errno));
> + rc = -1;
> + }
> + spapr->htab_fd_stale = false;
> + }
> +
> + pthread_mutex_unlock(&spapr->htab_mutex);
> + return rc;
> +}
> +
> +
2 empty lines, should be one.
> static void ppc_spapr_reset(void)
> {
> PowerPCCPU *first_ppc_cpu;
> @@ -984,7 +1016,10 @@ static int htab_save_setup(QEMUFile *f, void *opaque)
> } else {
> assert(kvm_enabled());
>
> + pthread_mutex_lock(&spapr->htab_mutex);
> spapr->htab_fd = kvmppc_get_htab_fd(false);
> + spapr->htab_fd_stale = false;
> + pthread_mutex_unlock(&spapr->htab_mutex);
> if (spapr->htab_fd < 0) {
> fprintf(stderr, "Unable to open fd for reading hash table from
> KVM: %s\n",
> strerror(errno));
> @@ -1137,6 +1172,11 @@ static int htab_save_iterate(QEMUFile *f, void *opaque)
> if (!spapr->htab) {
> assert(kvm_enabled());
>
> + rc = spapr_check_htab_fd(spapr);
> + if (rc < 0) {
> + return rc;
> + }
> +
> rc = kvmppc_save_htab(f, spapr->htab_fd,
> MAX_KVM_BUF_SIZE, MAX_ITERATION_NS);
> if (rc < 0) {
> @@ -1168,6 +1208,11 @@ static int htab_save_complete(QEMUFile *f, void
> *opaque)
>
> assert(kvm_enabled());
>
> + rc = spapr_check_htab_fd(spapr);
> + if (rc < 0) {
> + return rc;
> + }
> +
> rc = kvmppc_save_htab(f, spapr->htab_fd, MAX_KVM_BUF_SIZE, -1);
> if (rc < 0) {
> return rc;
> @@ -1355,6 +1400,8 @@ static void ppc_spapr_init(MachineState *machine)
> spapr->htab_shift++;
> }
>
> + pthread_mutex_init(&spapr->htab_mutex, NULL);
> +
> /* Set up Interrupt Controller before we create the VCPUs */
> spapr->icp = xics_system_init(smp_cpus * kvmppc_smt_threads() /
> smp_threads,
> XICS_IRQS);
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 749daf4..5e29bec 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -37,6 +37,8 @@ typedef struct sPAPREnvironment {
> int htab_save_index;
> bool htab_first_pass;
> int htab_fd;
> + bool htab_fd_stale;
> + pthread_mutex_t htab_mutex;
> } sPAPREnvironment;
>
> #define H_SUCCESS 0
>
--
Alexey
