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Blame SOURCES/kvm-atapi-migration-Throw-recoverable-error-to-avoid-rec.patch

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From e44bfb41173183a85bb6fa94a6f48486ac4ab0a2 Mon Sep 17 00:00:00 2001
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Tue, 10 Feb 2015 11:45:36 +0100
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Subject: [PATCH 10/16] atapi migration: Throw recoverable error to avoid
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 recovery
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Message-id: <1423568736-19538-3-git-send-email-dgilbert@redhat.com>
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Patchwork-id: 63779
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O-Subject: [RHEL-7.2 qemu-kvm PATCH 2/2] atapi migration: Throw recoverable error to avoid recovery
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Bugzilla: 892258
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RH-Acked-by: Juan Quintela <quintela@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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(With the previous atapi_dma flag recovery)
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If migration happens between the ATAPI command being written and the
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bmdma being started, the DMA is dropped.  Eventually the guest times
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out and recovers, but that can take many seconds.
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(This is rare, on a pingpong reading the CD continuously I hit
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this about ~1/30-1/50 migrates)
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I don't think we've got enough state to be able to recover safely
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at this point, so I throw a 'medium error, no seek complete'
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that I'm assuming guests will try and recover from an apparently
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dirty CD.
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OK, it's a hack, the real solution is probably to push a lot of
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ATAPI state into the migration stream, but this is a fix that
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works with no stream changes. Tested only on Linux (both RHEL5
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(pre-libata) and RHEL7).
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Reviewed-by: John Snow <jsnow@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit a71754e5b03fd3b8b8c6d3bc2a39f75bead729de)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 hw/ide/atapi.c    | 17 +++++++++++++++++
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 hw/ide/internal.h |  2 ++
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 hw/ide/pci.c      | 11 +++++++++++
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 3 files changed, 30 insertions(+)
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diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
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index 05e60b1..46a2c26 100644
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--- a/hw/ide/atapi.c
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+++ b/hw/ide/atapi.c
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@@ -393,6 +393,23 @@ static void ide_atapi_cmd_read(IDEState *s, int lba, int nb_sectors,
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     }
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 }
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+
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+/* Called by *_restart_bh when the transfer function points
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+ * to ide_atapi_cmd
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+ */
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+void ide_atapi_dma_restart(IDEState *s)
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+{
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+    /*
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+     * I'm not sure we have enough stored to restart the command
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+     * safely, so give the guest an error it should recover from.
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+     * I'm assuming most guests will try to recover from something
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+     * listed as a medium error on a CD; it seems to work on Linux.
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+     * This would be more of a problem if we did any other type of
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+     * DMA operation.
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+     */
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+    ide_atapi_cmd_error(s, MEDIUM_ERROR, ASC_NO_SEEK_COMPLETE);
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+}
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+
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 static inline uint8_t ide_atapi_set_profile(uint8_t *buf, uint8_t *index,
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                                             uint16_t profile)
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 {
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diff --git a/hw/ide/internal.h b/hw/ide/internal.h
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index 048a052..0a2d6bc 100644
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--- a/hw/ide/internal.h
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+++ b/hw/ide/internal.h
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@@ -289,6 +289,7 @@ typedef struct IDEDMAOps IDEDMAOps;
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 #define ATAPI_INT_REASON_TAG            0xf8
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 /* same constants as bochs */
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+#define ASC_NO_SEEK_COMPLETE                 0x02
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 #define ASC_ILLEGAL_OPCODE                   0x20
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 #define ASC_LOGICAL_BLOCK_OOR                0x21
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 #define ASC_INV_FIELD_IN_CMD_PACKET          0x24
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@@ -536,6 +537,7 @@ void ide_dma_error(IDEState *s);
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 void ide_atapi_cmd_ok(IDEState *s);
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 void ide_atapi_cmd_error(IDEState *s, int sense_key, int asc);
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+void ide_atapi_dma_restart(IDEState *s);
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 void ide_atapi_io_error(IDEState *s, int ret);
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 void ide_ioport_write(void *opaque, uint32_t addr, uint32_t val);
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diff --git a/hw/ide/pci.c b/hw/ide/pci.c
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index 635a364..cf7acb0 100644
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--- a/hw/ide/pci.c
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+++ b/hw/ide/pci.c
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@@ -220,6 +220,17 @@ static void bmdma_restart_bh(void *opaque)
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         }
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     } else if (error_status & BM_STATUS_RETRY_FLUSH) {
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         ide_flush_cache(bmdma_active_if(bm));
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+    } else {
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+        IDEState *s = bmdma_active_if(bm);
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+
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+        /*
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+         * We've not got any bits to tell us about ATAPI - but
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+         * we do have the end_transfer_func that tells us what
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+         * we're trying to do.
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+         */
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+        if (s->end_transfer_func == ide_atapi_cmd) {
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+            ide_atapi_dma_restart(s);
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+        }
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     }
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 }
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-- 
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1.8.3.1
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