[PATCH v13 58/85] KVM: RISC-V: Mark "struct page" pfns accessed before dropping mmu_lock

Sean Christopherson
2024-10-10T19:28:44Z

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 (see the link below).
Do both under mmu_lock to minimize the chances of doing the wrong thing in
the future.

Link: https://lore.kernel.org/all/cover.1683044162.git.lstoakes@gmail.com
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/riscv/kvm/mmu.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index 06aa5a0d056d..2e9aee518142 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -682,11 +682,11 @@ int kvm_riscv_gstage_map(struct kvm_vcpu *vcpu,

out_unlock:
if ((!ret || ret == -EEXIST) && writable)
- kvm_set_pfn_dirty(hfn);
+ kvm_release_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;