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From 5770fe43fe1e15e6f53cfd3705605e8645b95a98 Mon Sep 17 00:00:00 2001
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Fri, 13 Mar 2020 17:17:08 +0000
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Subject: [PATCH 20/20] exec/rom_reset: Free rom data during inmigrate skip
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Message-id: <20200313171708.242774-1-dgilbert@redhat.com>
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Patchwork-id: 94292
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O-Subject: [RHEL-AV-8.2.0 qemu-kvm PATCH 1/1] exec/rom_reset: Free rom data during inmigrate skip
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Bugzilla: 1809380
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RH-Acked-by: Daniel P. Berrange <berrange@redhat.com>
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RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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bz: https://bugzilla.redhat.com/show_bug.cgi?id=1809380
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brew: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=27249921
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branch: rhel-av-8.2.0
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upstream: Posted and with review-by, not merged yet
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Commit 355477f8c73e9 skips rom reset when we're an incoming migration
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so as not to overwrite shared ram in the ignore-shared migration
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optimisation.
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However, it's got an unexpected side effect that because it skips
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freeing the ROM data, when rom_reset gets called later on, after
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migration (e.g. during a reboot), the ROM does get reset to the original
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file contents.  Because of seabios/x86's weird reboot process
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this confuses a reboot into hanging after a migration.
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Fixes: 355477f8c73e9 ("migration: do not rom_reset() during incoming migration")
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https://bugzilla.redhat.com/show_bug.cgi?id=1809380
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 hw/core/loader.c | 25 ++++++++++++++++---------
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 1 file changed, 16 insertions(+), 9 deletions(-)
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diff --git a/hw/core/loader.c b/hw/core/loader.c
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index 5099f27..375b29b 100644
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--- a/hw/core/loader.c
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+++ b/hw/core/loader.c
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@@ -1118,19 +1118,26 @@ static void rom_reset(void *unused)
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 {
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     Rom *rom;
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-    /*
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-     * We don't need to fill in the RAM with ROM data because we'll fill
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-     * the data in during the next incoming migration in all cases.  Note
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-     * that some of those RAMs can actually be modified by the guest on ARM
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-     * so this is probably the only right thing to do here.
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-     */
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-    if (runstate_check(RUN_STATE_INMIGRATE))
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-        return;
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-
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     QTAILQ_FOREACH(rom, &roms, next) {
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         if (rom->fw_file) {
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             continue;
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         }
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+        /*
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+         * We don't need to fill in the RAM with ROM data because we'll fill
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+         * the data in during the next incoming migration in all cases.  Note
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+         * that some of those RAMs can actually be modified by the guest.
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+         */
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+        if (runstate_check(RUN_STATE_INMIGRATE)) {
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+            if (rom->data && rom->isrom) {
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+                /*
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+                 * Free it so that a rom_reset after migration doesn't
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+                 * overwrite a potentially modified 'rom'.
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+                 */
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+                rom_free_data(rom);
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+            }
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+            continue;
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+        }
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+
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         if (rom->data == NULL) {
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             continue;
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         }
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-- 
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1.8.3.1
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