Re: [PATCH v12 57/84] KVM: RISC-V: Mark "struct page" pfns accessed before dropping mmu_lock

Andrew Jones
2024-07-31T08:12:42Z

On Fri, Jul 26, 2024 at 04:52:06PM GMT, Sean Christopherson wrote:
> Mark pages accessed before dropping mmu_lock when faulting in guest memory
> so that RISC-V can convert to kvm_release_faultin_page() without tripping
> its lockdep assertion on mmu_lock being held. Marking pages accessed
> outside of mmu_lock is ok (not great, but safe), but marking pages _dirty_
> outside of mmu_lock can make filesystems unhappy.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/riscv/kvm/mmu.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index 06aa5a0d056d..806f68e70642 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -683,10 +683,10 @@ int kvm_riscv_gstage_map(struct kvm_vcpu *vcpu,
> out_unlock:
> if ((!ret || ret == -EEXIST) && writable)
> kvm_set_pfn_dirty(hfn);
> + else
> + kvm_release_pfn_clean(hfn);
>
> spin_unlock(&kvm->mmu_lock);
> - kvm_set_pfn_accessed(hfn);
> - kvm_release_pfn_clean(hfn);
> return ret;
> }
>
> --
> 2.46.0.rc1.232.g9752f9e123-goog
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>