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[Qemu-stable] [PATCH 04/21] migration: Fix madvise breakage if host and
From: |
Michael Roth |
Subject: |
[Qemu-stable] [PATCH 04/21] migration: Fix madvise breakage if host and guest have different page sizes |
Date: |
Wed, 16 Jan 2013 10:49:06 -0600 |
From: David Gibson <address@hidden>
madvise(DONTNEED) will throw away the contents of the whole page at the
given address, even if the given length is less than the page size. One
can argue about whether that's the correct behaviour, but that's what it's
done for a long time in Linux at least.
That means that the madvise() in ram_load(), on a setup where
TARGET_PAGE_SIZE is smaller than the host page size, can throw away data
in guest pages adjacent to the one it's actually processing right now,
leading to guest memory corruption on an incoming migration.
This patch therefore, disables the madvise() if the host page size is
larger than TARGET_PAGE_SIZE. This means we don't get the benefits of that
madvise() in this case, but a more complete fix is more difficult to
accomplish. This at least fixes the guest memory corruption.
Signed-off-by: David Gibson <address@hidden>
Reported-by: Alexey Kardashevskiy <address@hidden>
Signed-off-by: Anthony Liguori <address@hidden>
(cherry picked from commit 45e6cee42b98d10e2e14885ab656541a9ffd5187)
Signed-off-by: Michael Roth <address@hidden>
---
arch_init.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch_init.c b/arch_init.c
index b75a4c5..83dcc53 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -840,7 +840,8 @@ static int ram_load(QEMUFile *f, void *opaque, int
version_id)
memset(host, ch, TARGET_PAGE_SIZE);
#ifndef _WIN32
if (ch == 0 &&
- (!kvm_enabled() || kvm_has_sync_mmu())) {
+ (!kvm_enabled() || kvm_has_sync_mmu()) &&
+ getpagesize() <= TARGET_PAGE_SIZE) {
qemu_madvise(host, TARGET_PAGE_SIZE, QEMU_MADV_DONTNEED);
}
#endif
--
1.7.9.5
- [Qemu-stable] Patch Round-up for stable 1.3.1, freeze Monday, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 02/21] Disable semaphores fallback code for OpenBSD, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 01/21] Fix semaphores fallback code, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 03/21] Fix off-by-1 error in RAM migration code, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 05/21] target-mips: Fix incorrect code and test for INSV, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 06/21] target-mips: Fix incorrect shift for SHILO and SHILOV, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 04/21] migration: Fix madvise breakage if host and guest have different page sizes,
Michael Roth <=
- [Qemu-stable] [PATCH 07/21] vfio-pci: Don't use kvm_irqchip_in_kernel, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 11/21] target-xtensa: fix ITLB/DTLB page protection flags, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 12/21] qxl: save qemu_create_displaysurface_from result, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 10/21] pixman: fix vnc tight png/jpeg support, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 16/21] buffered_file: do not send more than s->bytes_xfer bytes per tick, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 20/21] vfio-pci: Loosen sanity checks to allow future features, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 14/21] e1000: Discard oversized packets based on SBP|LPE, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 18/21] vfio-pci: Make host MSI-X enable track guest, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 13/21] qxl+vnc: register a vm state change handler for dummy spice_server, Michael Roth, 2013/01/16
- [Qemu-stable] [PATCH 17/21] target-xtensa: fix search_pc for the last TB opcode, Michael Roth, 2013/01/16