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[PULL 12/12] KVM: Fix dirty ring mmap incorrect size due to renaming acc
From: |
Paolo Bonzini |
Subject: |
[PULL 12/12] KVM: Fix dirty ring mmap incorrect size due to renaming accident |
Date: |
Wed, 23 Jun 2021 14:14:24 +0200 |
From: Peter Xu <peterx@redhat.com>
Found this when I wanted to try the per-vcpu dirty rate series out, then I
found that it's not really working and it can quickly hang death a guest. I
found strange errors (e.g. guest crash after migration) happens even without
the per-vcpu dirty rate series.
When merging dirty ring, probably no one notice that the trivial renaming diff
[1] missed two existing references of kvm_dirty_ring_sizes; they do matter
since otherwise we'll mmap() a shorter range of memory after the renaming.
I think it didn't SIGBUS for me easily simply because some other stuff within
qemu mmap()ed right after the dirty rings (e.g. when testing 4096 slots, it
aligned with one small page on x86), so when we access the rings we've been
reading/writting to random memory elsewhere of qemu.
Fix the two sizes when map/unmap the shared dirty gfn memory.
[1]
https://lore.kernel.org/qemu-devel/dac5f0c6-1bca-3daf-e5d2-6451dbbaca93@redhat.com/
Cc: Hyman Huang <huangy81@chinatelecom.cn>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20210609014355.217110-1-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
accel/kvm/kvm-all.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index c7ec538850..e5b10dd129 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -411,7 +411,7 @@ static int do_kvm_destroy_vcpu(CPUState *cpu)
}
if (cpu->kvm_dirty_gfns) {
- ret = munmap(cpu->kvm_dirty_gfns, s->kvm_dirty_ring_size);
+ ret = munmap(cpu->kvm_dirty_gfns, s->kvm_dirty_ring_bytes);
if (ret < 0) {
goto err;
}
@@ -495,7 +495,7 @@ int kvm_init_vcpu(CPUState *cpu, Error **errp)
if (s->kvm_dirty_ring_size) {
/* Use MAP_SHARED to share pages with the kernel */
- cpu->kvm_dirty_gfns = mmap(NULL, s->kvm_dirty_ring_size,
+ cpu->kvm_dirty_gfns = mmap(NULL, s->kvm_dirty_ring_bytes,
PROT_READ | PROT_WRITE, MAP_SHARED,
cpu->kvm_fd,
PAGE_SIZE * KVM_DIRTY_LOG_PAGE_OFFSET);
--
2.31.1
- [PULL 09/12] configure, meson: convert libusb detection to meson, (continued)
- [PULL 09/12] configure, meson: convert libusb detection to meson, Paolo Bonzini, 2021/06/23
- [PULL 02/12] meson: drop unused CONFIG_GCRYPT_HMAC, Paolo Bonzini, 2021/06/23
- [PULL 01/12] target/i386: kvm: add support for TSC scaling, Paolo Bonzini, 2021/06/23
- [PULL 07/12] configure, meson: convert libtasn1 detection to meson, Paolo Bonzini, 2021/06/23
- [PULL 08/12] configure, meson: convert pam detection to meson, Paolo Bonzini, 2021/06/23
- [PULL 06/12] configure, meson: convert crypto detection to meson, Paolo Bonzini, 2021/06/23
- [PULL 10/12] configure, meson: convert libcacard detection to meson, Paolo Bonzini, 2021/06/23
- [PULL 11/12] configure, meson: convert libusbredir detection to meson, Paolo Bonzini, 2021/06/23
- [PULL 12/12] KVM: Fix dirty ring mmap incorrect size due to renaming accident,
Paolo Bonzini <=
- Re: [PULL 00/12] Misc, mostly meson patches for 2021-06-23, Peter Maydell, 2021/06/24