From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43102) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xm8gp-0001lA-KW for qemu-devel@nongnu.org; Wed, 05 Nov 2014 17:04:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Xm8gi-0003WB-4y for qemu-devel@nongnu.org; Wed, 05 Nov 2014 17:04:31 -0500 Message-ID: <545A9EE5.5050600@suse.de> Date: Wed, 05 Nov 2014 23:04:21 +0100 From: Alexander Graf MIME-Version: 1.0 References: <1415168221-2324-1-git-send-email-sam.mj@au1.ibm.com> <1415168221-2324-3-git-send-email-sam.mj@au1.ibm.com> <5459DA66.6070602@suse.de> <545A9E13.2000804@au1.ibm.com> In-Reply-To: <545A9E13.2000804@au1.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/2] spapr: Fix stale HTAB during live migration (TCG) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: sam.mj@au1.ibm.com, qemu-ppc@nongnu.org, qemu-devel@nongnu.org On 05.11.14 23:00, Samuel Mendoza-Jonas wrote: > On 05/11/14 19:05, Alexander Graf wrote: >> >> >> On 05.11.14 07:17, Samuel Mendoza-Jonas wrote: >>> If a TCG guest reboots during a running migration HTAB entries are not >>> marked dirty, and the destination boots with an invalid HTAB. >>> >>> When a reboot occurs reset the state of HTAB migration, and explicitly >>> inform the destination of invalid entries. >>> >>> Signed-off-by: Samuel Mendoza-Jonas >>> --- >>> hw/ppc/spapr.c | 59 +++++++++++++++++++++++++++++++++++--------------- >>> include/hw/ppc/spapr.h | 1 + >>> 2 files changed, 42 insertions(+), 18 deletions(-) >>> >>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c >>> index 1610c28..9f419e8 100644 >>> --- a/hw/ppc/spapr.c >>> +++ b/hw/ppc/spapr.c >>> @@ -829,26 +829,30 @@ static void spapr_reset_htab(sPAPREnvironment *spapr) >>> >>> shift = kvmppc_reset_htab(spapr->htab_shift); >>> >>> + pthread_mutex_lock(&spapr->htab_mutex); >>> if (shift > 0) { >>> /* 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) { >>> 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 */ >>> spapr->htab = qemu_memalign(HTAB_SIZE(spapr), HTAB_SIZE(spapr)); >>> + } else { >>> + spapr->htab_mig_full = true; >>> + spapr->htab_first_pass = true; >>> + spapr->htab_save_index = 0; >> >> You could just set the dirty bitmap to "all dirty" here, no? Then you >> don't need all the changes belong I presume? > > Yes, then you just need to reset htab_save_index to zero. The idea of this approach > was to avoid walking the HTAB twice (once to dirty and once to read it). But it is > a lot of changes for a fairly small benefit. If setting it dirty is preferred I'll > test and send that version. Thanks! Yes, please. I would prefer to keep this code as simple as I can ;). And the less corner cases we need to watch out for, the easier it becomes. Alex