Re: [RFC v2 PATCH 13/13] KVM: Enable memfd based page invalidation/fallocate
From: Kirill A. Shutemov <hidden>
Date: 2021-11-22 14:16:52
Also in:
kvm, linux-fsdevel, lkml, qemu-devel
On Fri, Nov 19, 2021 at 09:47:39PM +0800, Chao Peng wrote:
quoted hunk ↗ jump to hunk
Since the memory backing store does not get notified when VM is destroyed so need check if VM is still live in these callbacks. Signed-off-by: Yu Zhang <redacted> Signed-off-by: Chao Peng <redacted> --- virt/kvm/memfd.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)diff --git a/virt/kvm/memfd.c b/virt/kvm/memfd.c index bd930dcb455f..bcfdc685ce22 100644 --- a/virt/kvm/memfd.c +++ b/virt/kvm/memfd.c@@ -12,16 +12,38 @@ #include <linux/memfd.h> const static struct guest_mem_ops *memfd_ops; +static bool vm_is_dead(struct kvm *vm) +{ + struct kvm *kvm; + + list_for_each_entry(kvm, &vm_list, vm_list) { + if (kvm == vm) + return false; + }
I don't think this is enough. The struct kvm can be freed and re-allocated from the slab and this function will give false-negetive. Maybe the kvm has to be tagged with a sequential id that incremented every allocation. This id can be checked here.
+ + return true; +}
-- Kirill A. Shutemov