From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34913) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y21uj-0007CM-4H for qemu-devel@nongnu.org; Fri, 19 Dec 2014 13:04:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Y21uc-0004JC-Rf for qemu-devel@nongnu.org; Fri, 19 Dec 2014 13:04:33 -0500 Message-ID: <5494642A.3070109@suse.de> Date: Fri, 19 Dec 2014 18:45:14 +0100 From: Alexander Graf MIME-Version: 1.0 References: <54915835.6030508@ilande.co.uk> <549159B6.6000006@suse.de> <54915F28.1090001@ilande.co.uk> <549164F5.5080902@suse.de> <5492DCAB.4050907@ilande.co.uk> <5492E8D6.3040503@suse.de> <549348E7.3020401@ilande.co.uk> <54935CE5.4090201@suse.de> <549403C2.8030902@ilande.co.uk> <54943249.2060902@ilande.co.uk> <54944F1E.7000604@ilande.co.uk> <54945779.9090103@ilande.co.uk> <54945D7E.3090409@suse.de> <5494608F.4010307@redhat.com> In-Reply-To: <5494608F.4010307@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Qemu-ppc] Unable to loadvm on qemu-system-ppc -M g3beige (keyboard freeze) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , Mark Cave-Ayland , Peter Maydell Cc: "qemu-ppc@nongnu.org" , qemu-devel On 19.12.14 18:29, Paolo Bonzini wrote: > > > On 19/12/2014 18:16, Alexander Graf wrote: >> >> >> On 19.12.14 17:51, Mark Cave-Ayland wrote: >>> On 19/12/14 16:35, Peter Maydell wrote: >>> >>>> On 19 December 2014 at 16:15, Mark Cave-Ayland >>>> wrote: >>>>> It looks like after restoring the CPU state with loadvm env->htab_base >>>>> is still at 0x0 rather than its pre-migration value of 0x7e000000. >>>> >>>> Odd -- there is code that is at least trying to do that: >>>> machine.c calls ppc_store_sdr1() which should set htab_base/mask >>>> according to the migrated value of the register... >>> >>> Stepping through ppc_store_sdr1() I see the problem is the if() statement: >>> >>> if (env->spr[SPR_SDR1] != value) { >>> .... >>> } >>> >>> It looks like env->spr[SPR_SDR1] has already been set to 0x7e000000 >>> before the call to ppc_store_sdr1() and so as the values are already >>> equal then the code to setup env->htab_mask and env->htab_base is bypassed. >>> >>> The quick fix is to comment out the above if() statement which allows me >>> to restore my OpenBIOS image successfully with -loadvm but sadly not my >>> OS image (I guess there are probably a few more state bugs still lying >>> around). Does this seem the right thing to do or is there a better way? >> >> How about something like this instead? Then we at least don't lose the >> acceleration we get from not invalidating the TLB on identical SDR1 writes. >> >> >> Alex >> >> >> diff --git a/target-ppc/machine.c b/target-ppc/machine.c >> index c801b82..6f347bf 100644 >> --- a/target-ppc/machine.c >> +++ b/target-ppc/machine.c >> @@ -71,6 +71,7 @@ static int cpu_load_old(QEMUFile *f, void *opaque, int >> version_id) >> for (i = 0; i < 1024; i++) >> qemu_get_betls(f, &env->spr[i]); >> if (!env->external_htab) { >> + env->spr[SPR_SDR1] = 0; >> ppc_store_sdr1(env, sdr1); >> } >> qemu_get_be32s(f, &env->vscr); > > Or even move the tlb_flush and if to the caller, g. It > is only needed there, and would get in the way if one day PPC were to > support --disable-tcg (which removes cputlb.c from the executable). Even better, yes. Alex