Re: [PULL 11/38] tests/qtest: migration-test: Add tests for file-based migration

[Fabiano Rosas <farosas@suse.de>]

Juan Quintela <quintela@redhat.com> writes:

> Fabiano Rosas <farosas@suse.de> wrote:
>> Juan Quintela <quintela@redhat.com> writes:
>>
>>> Fabiano Rosas <farosas@suse.de> wrote:
>>> D> Juan Quintela <quintela@redhat.com> writes:
>>>>
>>>>> From: Fabiano Rosas <farosas@suse.de>
>>>>>
>>>>> Add basic tests for file-based migration.
>>>>>
>>>>> Note that we cannot use test_precopy_common because that routine
>>>>> expects it to be possible to run the migration live. With the file
>>>>> transport there is no live migration because we must wait for the
>>>>> source to finish writing the migration data to the file before the
>>>>> destination can start reading. Add a new migration function
>>>>> specifically to handle the file migration.
>>>>>
>>>>> Reviewed-by: Peter Xu <peterx@redhat.com>
>>>>> Reviewed-by: Juan Quintela <quintela@redhat.com>
>>>>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>>>>> Signed-off-by: Juan Quintela <quintela@redhat.com>
>>>>> Message-ID: <20230712190742.22294-7-farosas@suse.de>
>>>
>>>>> +static void file_offset_finish_hook(QTestState *from, QTestState *to,
>>>>> +                                    void *opaque)
>>>>> +{
>>>>> +#if defined(__linux__)
>>>>> +    g_autofree char *path = g_strdup_printf("%s/%s", tmpfs, FILE_TEST_FILENAME);
>>>>> +    size_t size = FILE_TEST_OFFSET + sizeof(QEMU_VM_FILE_MAGIC);
>>>>> +    uintptr_t *addr, *p;
>>>>> +    int fd;
>>>>> +
>>>>> +    fd = open(path, O_RDONLY);
>>>>> +    g_assert(fd != -1);
>>>>> +    addr = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
>>>>> +    g_assert(addr != MAP_FAILED);
>>>>> +
>>>>> +    /*
>>>>> +     * Ensure the skipped offset contains zeros and the migration
>>>>> +     * stream starts at the right place.
>>>>> +     */
>>>>> +    p = addr;
>>>>> +    while (p < addr + FILE_TEST_OFFSET / sizeof(uintptr_t)) {
>>>>> +        g_assert(*p == 0);
>>>>> +        p++;
>>>>> +    }
>>>>> +    g_assert_cmpint(cpu_to_be32(*p), ==, QEMU_VM_FILE_MAGIC);
>>>>
>>>> This truncates to 32-bits, so it breaks on a BE host. We need this:
>>>>
>>>> -->8--
>>>> From ea0c2d1c988add48d9754891a9fc7f6854a9718a Mon Sep 17 00:00:00 2001
>>>> From: Fabiano Rosas <farosas@suse.de>
>>>> Date: Mon, 16 Oct 2023 15:21:49 -0300
>>>> Subject: [PATCH] fixup! tests/qtest: migration-test: Add tests for file-based
>>>>  migration
>>>>
>>>> ---
>>>>  tests/qtest/migration-test.c | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
>>>> index da02b6d692..e1c110537b 100644
>>>> --- a/tests/qtest/migration-test.c
>>>> +++ b/tests/qtest/migration-test.c
>>>> @@ -1966,7 +1966,7 @@ static void file_offset_finish_hook(QTestState *from, QTestState *to,
>>>>          g_assert(*p == 0);
>>>>          p++;
>>>>      }
>>>> -    g_assert_cmpint(cpu_to_be32(*p), ==, QEMU_VM_FILE_MAGIC);
>>>> +    g_assert_cmpint(cpu_to_be64(*p) >> 32, ==, QEMU_VM_FILE_MAGIC);
>>>>  
>>>>      munmap(addr, size);
>>>>      close(fd);
>>>
>>> I am resubmitting with this change.
>>>
>>> But I think we need to change this:
>>>
>>>>> +    g_autofree char *path = g_strdup_printf("%s/%s", tmpfs, FILE_TEST_FILENAME);
>>>>> +    size_t size = FILE_TEST_OFFSET + sizeof(QEMU_VM_FILE_MAGIC);
>>>>> +    uintptr_t *addr, *p;
>>>
>>> I think we should change the test so the file is 64 bits on every
>>> architecture.
>>> Then we can cast to void * or uintptr_t as needed.
>>
>> Hm, I don't get what you mean here. What needs to be 64 bits?
>
> size_t is 32 bits on 32bits host, and 64 bits on 64 bits host.
> uintprt_t is the same.

Right, I have thought of that when writing this fix yesterday, but I
dismissed it because I thought we were never have a 32bit host running
these tests.

> So using explicit sizes:
>
> static void file_offset_finish_hook(QTestState *from, QTestState *to,
>                                     void *opaque)
> {
> #if defined(__linux__)
>     g_autofree char *path = g_strdup_printf("%s/%s", tmpfs, FILE_TEST_FILENAME);
>     size_t size = FILE_TEST_OFFSET + sizeof(QEMU_VM_FILE_MAGIC);
>     uint64_t *addr, *p;
>     int fd;
>
>     fd = open(path, O_RDONLY);
>     g_assert(fd != -1);
>     addr = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
>     g_assert(addr != MAP_FAILED);
>
>     /*
>      * Ensure the skipped offset contains zeros and the migration
>      * stream starts at the right place.
>      */
>     p = addr;
>     while (p < (uintprt_t)addr + FILE_TEST_OFFSET) {
>         g_assert(*p == 0);
>         p++;
>     }
>     g_assert_cmpint(cpu_to_be64(*p) >> 32, ==, QEMU_VM_FILE_MAGIC);
>
>     munmap(addr, size);
>     close(fd);
> #endif
> }
>
> This is completely untested, but it should make sure that we are reading
> 64bits integers in both 32 and 64 bits hosts, no?

Looks like it. I can give it a try and send an update as a separate
patch.