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Blame SOURCES/kvm-Fix-memory-slot-page-alignment-logic-bug-1455745.patch

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From be6123e0eadd895a9fa47005df38c4dce655236c Mon Sep 17 00:00:00 2001
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Tue, 6 Jun 2017 17:08:19 +0200
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Subject: [PATCH 1/6] kvm: Fix memory slot page alignment logic (bug#1455745)
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RH-Author: Paolo Bonzini <pbonzini@redhat.com>
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Message-id: <20170606170819.18875-1-pbonzini@redhat.com>
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Patchwork-id: 75507
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O-Subject: [RHEL7.4 qemu-kvm PATCH] kvm: Fix memory slot page alignment logic (bug#1455745)
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Bugzilla: 1455745
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RH-Acked-by: Alex Williamson <alex.williamson@redhat.com>
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RH-Acked-by: Marcel Apfelbaum <marcel@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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From: Alexander Graf <agraf@suse.de>
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Brew build: 13356300
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Memory slots have to be page aligned to get entered into KVM. There
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is existing logic that tries to ensure that we pad memory slots that
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are not page aligned to the biggest region that would still fit in the
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alignment requirements.
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Unfortunately, that logic is broken. It tries to calculate the start
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offset based on the region size.
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Fix up the logic to do the thing it was intended to do and document it
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properly in the comment above it.
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With this patch applied, I can successfully run an e500 guest with more
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than 3GB RAM (at which point RAM starts overlapping subpage memory regions).
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[Paolo: in RHEL's case, the issue was reported with assigned devices]
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Alexander Graf <agraf@suse.de>
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(cherry picked from commit f2a64032a14c642d0ddc9a7a846fc3d737deede5)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 kvm-all.c | 6 ++++--
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 1 file changed, 4 insertions(+), 2 deletions(-)
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diff --git a/kvm-all.c b/kvm-all.c
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index fc6e3ab..9486b9a 100644
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--- a/kvm-all.c
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+++ b/kvm-all.c
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@@ -621,8 +621,10 @@ static void kvm_set_phys_mem(MemoryRegionSection *section, bool add)
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     unsigned delta;
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     /* kvm works in page size chunks, but the function may be called
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-       with sub-page size and unaligned start address. */
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-    delta = TARGET_PAGE_ALIGN(size) - size;
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+       with sub-page size and unaligned start address. Pad the start
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+       address to next and truncate size to previous page boundary. */
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+    delta = (TARGET_PAGE_SIZE - (start_addr & ~TARGET_PAGE_MASK));
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+    delta &= ~TARGET_PAGE_MASK;
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     if (delta > size) {
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         return;
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     }
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-- 
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1.8.3.1
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