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Re: [Qemu-devel] [RFC 06/19] fuzz: Add ramfile for fast vmstate/vmload
From: |
Oleinik, Alexander |
Subject: |
Re: [Qemu-devel] [RFC 06/19] fuzz: Add ramfile for fast vmstate/vmload |
Date: |
Fri, 26 Jul 2019 19:36:39 +0000 |
On 7/26/19 8:47 AM, Stefan Hajnoczi wrote:
> On Thu, Jul 25, 2019 at 03:23:49AM +0000, Oleinik, Alexander wrote:
>> The ramfile allows vmstate to be saved and restored directly onto the
>> heap.
>>
>> Signed-off-by: Alexander Oleinik <address@hidden>
>> ---
>> tests/fuzz/ramfile.c | 127 +++++++++++++++++++++++++++++++++++++++++++
>> tests/fuzz/ramfile.h | 20 +++++++
>> 2 files changed, 147 insertions(+)
>> create mode 100644 tests/fuzz/ramfile.c
>> create mode 100644 tests/fuzz/ramfile.h
>>
>> diff --git a/tests/fuzz/ramfile.c b/tests/fuzz/ramfile.c
>> new file mode 100644
>> index 0000000000..8da242e9ee
>> --- /dev/null
>> +++ b/tests/fuzz/ramfile.c
>
> Please put this in migration/. This code doesn't do fuzzing and is
> general-purpose enough to be used by other parts of QEMU dealing with
> live migration.
>
>> @@ -0,0 +1,127 @@
>> +/*
>> + *
>> =====================================================================================
>> + *
>> + * Filename: ramfile.c
>> + *
>> + * Description: QEMUFile stored in dynamically allocated RAM for fast
>> VMRestore
>> + *
>> + * Author: Alexander Oleinik (), address@hidden
>> + * Organization:
>> + *
>> + *
>> =====================================================================================
>> + */
>
> Please use license headers with all new files that are created.
> Fine-grained filename and authorship information is already kept by git
> so it's not necessary to duplicate it here.
>
>> +#include <stdlib.h>
>> +#include "qemu/osdep.h"
>
> osdep.h already includes stdlib.h.
>
>> +#include "qemu-common.h"
>> +#include "exec/memory.h"
>> +#include "migration/qemu-file.h"
>> +#include "migration/migration.h"
>> +#include "migration/savevm.h"
>> +#include "ramfile.h"
>> +
>> +#define INCREMENT 10240
>> +#define IO_BUF_SIZE 32768
>> +#define MAX_IOV_SIZE MIN(IOV_MAX, 64)
>> +
>> +struct QEMUFile {
>> + const QEMUFileOps *ops;
>> + const QEMUFileHooks *hooks;
>> + void *opaque;
>> +
>> + int64_t bytes_xfer;
>> + int64_t xfer_limit;
>> +
>> + int64_t pos; /* start of buffer when writing, end of buffer
>> + when reading */
>> + int buf_index;
>> + int buf_size; /* 0 when writing */
>> + uint8_t buf[IO_BUF_SIZE];
>> +
>> + DECLARE_BITMAP(may_free, MAX_IOV_SIZE);
>> + struct iovec iov[MAX_IOV_SIZE];
>> + unsigned int iovcnt;
>> +
>> + int last_error;
>> +};
>
> Wait, what?! :)
>
> Please add the ram file to qemu-file.c instead of duplicating QEMUFile.
>
I think we should be able to replace all of this simply by using
memfd_create. Since it acts as a regular file, it will work with the
existing code (likely with performance gains).
- [Qemu-devel] [RFC 08/19] fuzz: add shims to intercept libfuzzer init, (continued)
- [Qemu-devel] [RFC 08/19] fuzz: add shims to intercept libfuzzer init, Oleinik, Alexander, 2019/07/24
- [Qemu-devel] [RFC 03/19] fuzz: add fuzz accelerator, Oleinik, Alexander, 2019/07/24
- [Qemu-devel] [RFC 05/19] fuzz: expose qemu_savevm_state & skip state header, Oleinik, Alexander, 2019/07/24
- [Qemu-devel] [RFC 06/19] fuzz: Add ramfile for fast vmstate/vmload, Oleinik, Alexander, 2019/07/24
- [Qemu-devel] [RFC 04/19] fuzz: Add qos support to fuzz targets, Oleinik, Alexander, 2019/07/24
- [Qemu-devel] [RFC 12/19] fuzz: hard-code all of the needed files for build, Oleinik, Alexander, 2019/07/24
- [Qemu-devel] [RFC 09/19] fuzz: use mtree_info to find mapped addresses, Oleinik, Alexander, 2019/07/24
- [Qemu-devel] [RFC 10/19] fuzz: expose real_main (aka regular vl.c:main), Oleinik, Alexander, 2019/07/24
- [Qemu-devel] [RFC 11/19] fuzz: add direct send/receive in qtest client, Oleinik, Alexander, 2019/07/24