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Re: [Qemu-devel] HEAD is failing virt-test on migration tests
From: |
Alexander Graf |
Subject: |
Re: [Qemu-devel] HEAD is failing virt-test on migration tests |
Date: |
Mon, 16 Feb 2015 21:24:02 +0100 |
User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 |
On 16.02.15 19:57, Dr. David Alan Gilbert wrote:
> * Alexander Graf (address@hidden) wrote:
>
> <snip>
>
>> Can you please test whether the patch below makes things work for you again?
>
> The patch below fixes RDMA migration (same host); however, see comments.
>
>> Alex
>>
>> From ef6fde21007e62529799264f57a65c6bb3d0d414 Mon Sep 17 00:00:00 2001
>> From: Alexander Graf <address@hidden>
>> Date: Sat, 14 Feb 2015 00:21:01 +0100
>> Subject: [PATCH] migration: Read JSON VM description on incoming migration
>>
>> One of the really nice things about the VM description format is that it
>> goes
>> over the wire when live migration is happening. Unfortunately QEMU today
>> closes
>> any socket once it sees VM_EOF coming, so we never give the VMDESC the
>> chance to
>> actually land on the wire.
>>
>> This patch makes QEMU read the description as well. This way we ensure that
>> anything wire tapping us in between will get the chance to also
>> interpret the
>> stream.
>>
>> Along the way we also fix virt tests that assume that number_bytes_sent
>> on the
>> sender side is equal to number_bytes_read which was true before the VMDESC
>> patches and is true again with this patch.
>>
>> Signed-off-by: Alexander Graf <address@hidden>
>>
>> diff --git a/savevm.c b/savevm.c
>> index 8040766..ff4bead 100644
>> --- a/savevm.c
>> +++ b/savevm.c
>> @@ -929,6 +929,7 @@ int qemu_loadvm_state(QEMUFile *f)
>> uint8_t section_type;
>> unsigned int v;
>> int ret;
>> + int file_error_after_eof = -1;
>>
>> if (qemu_savevm_state_blocked(&local_err)) {
>> error_report("%s", error_get_pretty(local_err));
>> @@ -1034,6 +1035,22 @@ int qemu_loadvm_state(QEMUFile *f)
>> }
>> }
>>
>> + file_error_after_eof = qemu_file_get_error(f);
>> +
>> + /*
>> + * Try to read in the VMDESC section as well, so that dumping tools
>> that
>> + * intercept our migration stream have the chance to see it.
>> + */
>> + if (qemu_get_byte(f) == QEMU_VM_VMDESCRIPTION) {
>
> You could use qemu_peek_byte for that?
It's what I had originally, but qemu_peek_byte() at the end of the day
is the exact same as qemu_get_byte, but doesn't increment the internal
buffer counter. So any error conditions that incur because the read
failed still happen with peek_byte and are a lot less intuitive.
>
>> + uint32_t size = qemu_get_be32(f);
>> + uint8_t *buf = g_malloc(size);
>> +
>> + if (buf) {
>> + qemu_get_buffer(f, buf, size);
>> + g_free(buf);
>> + }
>
> This is slightly dangerous; a malformed file could send you a huge
> value and get you to allocate lots of memory for no good reason.
>
> You could do some clever; but personally I'd just loop around a
> nice small buffer until it's gone.
Good idea. Will change.
> As mentioned on IRC; I'm still worried though that this is only
> a fix for loading on newer versions; migration to an older QEMU
> with the same machine type would fail.
> (Yes I know mythically that no one cares about this; but I do).
Yeah, I guess I'll follow up with a fix to disable VMDESC submission on
older versions, just to be on the safe side.
Alex
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, (continued)
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Lucas Meneghel Rodrigues, 2015/02/12
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Lucas Meneghel Rodrigues, 2015/02/12
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Lucas Meneghel Rodrigues, 2015/02/12
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Alexander Graf, 2015/02/12
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Dr. David Alan Gilbert, 2015/02/13
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Alexander Graf, 2015/02/13
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Dr. David Alan Gilbert, 2015/02/13
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Lucas Meneghel Rodrigues, 2015/02/13
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Alexander Graf, 2015/02/13
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Dr. David Alan Gilbert, 2015/02/16
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests,
Alexander Graf <=
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Paolo Bonzini, 2015/02/16
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Alexander Graf, 2015/02/16
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Paolo Bonzini, 2015/02/16
- Re: [Qemu-devel] HEAD is failing virt-test on migration tests, Lucas Meneghel Rodrigues, 2015/02/13