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kvm: x86/mmu: Warn on linking when sp->unsync_children

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Since the commit 65855ed8b034 ("KVM: X86: Synchronize the shadow
pagetable before link it"), no sp would be linked with
sp->unsync_children = 1.

So make it WARN if it is the case.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Message-Id: <20221212090106.378206-1-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Lai Jiangshan 2022-12-12 17:01:06 +08:00 committed by Paolo Bonzini
parent 1567037614
commit 641e680858
1 changed files with 10 additions and 1 deletions
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11
arch/x86/kvm/mmu/mmu.c
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@ -2355,7 +2355,16 @@ static void __link_shadow_page(struct kvm *kvm,
mmu_page_add_parent_pte(cache, sp, sptep);
if (sp->unsync_children || sp->unsync)
/*
* The non-direct sub-pagetable must be updated before linking. For
* L1 sp, the pagetable is updated via kvm_sync_page() in
* kvm_mmu_find_shadow_page() without write-protecting the gfn,
* so sp->unsync can be true or false. For higher level non-direct
* sp, the pagetable is updated/synced via mmu_sync_children() in
* FNAME(fetch)(), so sp->unsync_children can only be false.
* WARN_ON_ONCE() if anything happens unexpectedly.
*/
if (WARN_ON_ONCE(sp->unsync_children) || sp->unsync)
mark_unsync(sptep);
}