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spapr: Fix stale HTAB during live migration (KVM) 

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.mj@au1.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Samuel Mendoza-Jonas 2014-11-17 15:12:28 +11:00 committed by Alexander Graf
parent e094c4c12f
commit 01a579729b
2 changed files with 39 additions and 0 deletions
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38
hw/ppc/spapr.c
View File

@ -833,6 +833,11 @@ 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 */
if (spapr->htab_fd >= 0) {
spapr->htab_fd_stale = true;
}
} else {
if (!spapr->htab) {
/* Allocate an htab if we don't yet have one */
@ -867,6 +872,28 @@ static int find_unknown_sysbus_device(SysBusDevice *sbdev, void *opaque)
return 0;
}
/*
* A guest reset will cause spapr->htab_fd to become stale if being used.
* Reopen the file descriptor to make sure the whole HTAB is properly read.
*/
static int spapr_check_htab_fd(sPAPREnvironment *spapr)
{
int rc = 0;
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;
}
return rc;
}
static void ppc_spapr_reset(void)
{
PowerPCCPU *first_ppc_cpu;
@ -1005,6 +1032,7 @@ static int htab_save_setup(QEMUFile *f, void *opaque)
assert(kvm_enabled());
spapr->htab_fd = kvmppc_get_htab_fd(false);
spapr->htab_fd_stale = false;
if (spapr->htab_fd < 0) {
fprintf(stderr, "Unable to open fd for reading hash table from KVM: %s\n",
strerror(errno));
@ -1157,6 +1185,11 @@ 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) {
@ -1188,6 +1221,11 @@ 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;

1
include/hw/ppc/spapr.h
View File

@ -37,6 +37,7 @@ typedef struct sPAPREnvironment {
int htab_save_index;
bool htab_first_pass;
int htab_fd;
bool htab_fd_stale;
} sPAPREnvironment;
#define H_SUCCESS 0