Re: [PATCH 04/12] KVM: MMU: WARN if PAE roots linger after kvm_mmu_unload

Sean Christopherson
2022-02-10T23:20:49Z

On Wed, Feb 09, 2022, Paolo Bonzini wrote:
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> arch/x86/kvm/mmu/mmu.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index e0c0f0bc2e8b..7b5765ced928 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -5065,12 +5065,21 @@ int kvm_mmu_load(struct kvm_vcpu *vcpu)
> return r;
> }
>
> +static void __kvm_mmu_unload(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu)
> +{
> + int i;
> + kvm_mmu_free_roots(vcpu, mmu, KVM_MMU_ROOTS_ALL);
> + WARN_ON(VALID_PAGE(mmu->root_hpa));
> + if (mmu->pae_root) {
> + for (i = 0; i < 4; ++i)
> + WARN_ON(IS_VALID_PAE_ROOT(mmu->pae_root[i]));
> + }

I'm somewhat ambivalent, but if you're at all on the fence, I vote to drop this
one. I've always viewed the WARN on root_hpa as gratuitous.

But, if it helped during development, then why not...