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Re: [Qemu-devel] [PATCH 2/3] migration: Test for disabled features on re
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 2/3] migration: Test for disabled features on reception |
Date: |
Tue, 15 Nov 2016 09:54:03 +0000 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
* Juan Quintela (address@hidden) wrote:
> Right now, if we receive a compressed page or a xbzrle page while this
> features are disabled, Bad Things (TM) can happen. Just add a test for
> them.
This confuses me; I didn't think until recently we could
guarantee anything about having the capabilities set on the destination
side. Until -incoming defer the destination didn't have a way of setting
capabilities in a known state before starting the reception.
Dave
> Signed-off-by: Juan Quintela <address@hidden>
> ---
> migration/ram.c | 23 ++++++++++++++++++++++-
> 1 file changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index fb9252d..4bb707c 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -2464,7 +2464,7 @@ static int ram_load_postcopy(QEMUFile *f)
>
> static int ram_load(QEMUFile *f, void *opaque, int version_id)
> {
> - int flags = 0, ret = 0;
> + int flags = 0, ret = 0, invalid_flags;
> static uint64_t seq_iter;
> int len = 0;
> /*
> @@ -2479,6 +2479,15 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
> ret = -EINVAL;
> }
>
> + invalid_flags = 0;
> +
> + if (!migrate_use_xbzrle()) {
> + invalid_flags |= RAM_SAVE_FLAG_XBZRLE;
> + }
> +
> + if (!migrate_use_compression()) {
> + invalid_flags |= RAM_SAVE_FLAG_COMPRESS_PAGE;
> + }
> /* This RCU critical section can be very long running.
> * When RCU reclaims in the code start to become numerous,
> * it will be necessary to reduce the granularity of this
> @@ -2499,6 +2508,18 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
> flags = addr & ~TARGET_PAGE_MASK;
> addr &= TARGET_PAGE_MASK;
>
> + if (flags & invalid_flags) {
> + if (flags & invalid_flags & RAM_SAVE_FLAG_XBZRLE) {
> + error_report("Received an unexpected XBRLE page");
> + }
> + if (flags & invalid_flags & RAM_SAVE_FLAG_COMPRESS_PAGE) {
> + error_report("Received an unexpected compressed page");
> + }
> +
> + ret = -EINVAL;
> + break;
> + }
> +
> if (flags & (RAM_SAVE_FLAG_COMPRESS | RAM_SAVE_FLAG_PAGE |
> RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) {
> RAMBlock *block = ram_block_from_stream(f, flags);
> --
> 2.7.4
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK