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From d05a64ddd01fa11fed479a2e249ed46c93207f9e Mon Sep 17 00:00:00 2001
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Thu, 18 May 2017 11:17:26 +0200
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Subject: [PATCH 19/27] migration: Fix non-multiple of page size migration
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RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Message-id: <20170518111727.7433-2-dgilbert@redhat.com>
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Patchwork-id: 75314
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O-Subject: [RHEL-7.4 qemu-kvm-rhev PATCH 1/2] migration: Fix non-multiple of page size migration
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Bugzilla: 1449037
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RH-Acked-by: Juan Quintela <quintela@redhat.com>
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RH-Acked-by: Peter Xu <peterx@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Unfortunately it's legal to create a VM with a RAM size that's
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not a multiple of the underlying host page or huge page size.
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Recently I'd changed things to always send host sized pages,
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and that breaks if we have say a 1025MB guest on 2MB hugepages.
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Unfortunately we can't just make that illegal since it would break
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migration from/to existing oddly configured VMs.
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Symptom: qemu-system-x86_64: Illegal RAM offset 40100000
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as it transmits the fraction of the hugepage after the end
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of the RAMBlock (may also cause a crash on the source
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- possibly due to clearing bits after the bitmap)
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Reported-by: Yumei Huang <yuhuang@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Conflicts
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Cleanup in HEAD got rid of pss->offset; so use pss->offset
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in our 2.9 world
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Upstream URL:
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http://lists.nongnu.org/archive/html/qemu-devel/2017-05/msg04392.html
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Upstream Message-Id: <20170518172453.32599-2-quintela@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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migration/ram.c | 10 +++++++++-
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1 file changed, 9 insertions(+), 1 deletion(-)
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diff --git a/migration/ram.c b/migration/ram.c
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index de1e0a3..3661bc8 100644
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--- a/migration/ram.c
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+++ b/migration/ram.c
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@@ -1304,6 +1304,13 @@ static int ram_save_target_page(MigrationState *ms, QEMUFile *f,
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* block.
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*
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* Returns: Number of pages written.
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+ * Starting at *offset send pages up to the end of the current host
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+ * page. It's valid for the initial offset to point into the middle of
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+ * a host page in which case the remainder of the hostpage is sent.
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+ * Only dirty target pages are sent. Note that the host page size may
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+ * be a huge page for this block.
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+ * The saving stops at the boundary of the used_length of the block
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+ * if the RAMBlock isn't a multiple of the host page size.
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*
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* @f: QEMUFile where to send the data
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* @block: pointer to block that contains the page we want to send
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@@ -1332,7 +1339,8 @@ static int ram_save_host_page(MigrationState *ms, QEMUFile *f,
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pages += tmppages;
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pss->offset += TARGET_PAGE_SIZE;
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dirty_ram_abs += TARGET_PAGE_SIZE;
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- } while (pss->offset & (pagesize - 1));
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+ } while ((pss->offset & (pagesize - 1)) &&
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+ offset_in_ramblock(pss->block, pss->offset));
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/* The offset we leave with is the last one we looked at */
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pss->offset -= TARGET_PAGE_SIZE;
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--
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1.8.3.1
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