On 4/27/22 17:54, Sasha Levin wrote:
From: Paolo Bonzini pbonzini@redhat.com
[ Upstream commit 9191b8f0745e63edf519e4a54a4aaae1d3d46fbd ]
WARN and bail if KVM attempts to free a root that isn't backed by a shadow page. KVM allocates a bare page for "special" roots, e.g. when using PAE paging or shadowing 2/3/4-level page tables with 4/5-level, and so root_hpa will be valid but won't be backed by a shadow page. It's all too easy to blindly call mmu_free_root_page() on root_hpa, be nice and WARN instead of crashing KVM and possibly the kernel.
Reviewed-by: Sean Christopherson seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org
arch/x86/kvm/mmu/mmu.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 7f009ebb319a..e7cd16e1e0a0 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3239,6 +3239,8 @@ static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa, return; sp = to_shadow_page(*root_hpa & PT64_BASE_ADDR_MASK);
- if (WARN_ON(!sp))
return;if (is_tdp_mmu_page(sp)) kvm_tdp_mmu_put_root(kvm, sp, false);
Acked-by: Paolo Bonzini pbonzini@redhat.com