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Re: [Qemu-devel] [PATCH 1/1] kvm_physical_sync_dirty_bitmap: ignore ENOE
From: |
Michael Tokarev |
Subject: |
Re: [Qemu-devel] [PATCH 1/1] kvm_physical_sync_dirty_bitmap: ignore ENOENT from kvm_vm_ioctl |
Date: |
Thu, 10 Apr 2014 20:30:21 +0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131103 Icedove/17.0.10 |
09.04.2014 07:21, Serge Hallyn wrote:
> ENOENT (iiuc) means the kernel has an empty dirty bitmap for this
> slot. Don't abort in that case. This appears to solve the bug
> reported at
>
> https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1303926
>
> which first showed up with commit b533f658a98325d: fix return check for
> KVM_GET_DIRTY_LOG ioctl
>
> Signed-off-by: Serge Hallyn <address@hidden>
> ---
> kvm-all.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kvm-all.c b/kvm-all.c
> index 82a9119..7b7ea8d 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -441,10 +441,13 @@ static int
> kvm_physical_sync_dirty_bitmap(MemoryRegionSection *section)
>
> d.slot = mem->slot;
>
> - if (kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d) == -1) {
> + ret = kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d);
> + if (ret < 0 && ret != -ENOENT) {
> DPRINTF("ioctl failed %d\n", errno);
> ret = -1;
> break;
> + } else if (ret < 0) {
> + ret = 0;
> }
>
> kvm_get_dirty_pages_log_range(section, d.dirty_bitmap);
Should we omit calling kvm_get_dirty_pages_log_range() if there's
no bitmap from kernel? In particular, do we trust kernel to not
touch d.dirty_bitmap when it returns ENOENT?
Thanks,
/mjt