[PATCH v12 62/84] KVM: PPC: Book3S: Mark "struct page" pfns dirty/accessed after installing PTE
From: Sean Christopherson <seanjc@google.com>
Date: 2024-07-26 23:54:47
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-mips, linux-riscv, lkml, loongarch
Subsystem:
kernel virtual machine for powerpc (kvm/powerpc), linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
Mark pages/folios dirty/accessed after installing a PTE, and more specifically after acquiring mmu_lock and checking for an mmu_notifier invalidation. Marking a page/folio dirty after it has been written back can make some filesystems unhappy (backing KVM guests will such filesystem files is uncommon, and the race is minuscule, hence the lack of complaints). See the link below for details. This will also allow converting Book3S to kvm_release_faultin_page(), which requires that mmu_lock be held (for the aforementioned reason). Link: https://lore.kernel.org/all/cover.1683044162.git.lstoakes@gmail.com (local) Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/powerpc/kvm/book3s_64_mmu_host.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_64_mmu_host.c b/arch/powerpc/kvm/book3s_64_mmu_host.c
index bc6a381b5346..d0e4f7bbdc3d 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_host.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_host.c@@ -121,13 +121,10 @@ int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte, vpn = hpt_vpn(orig_pte->eaddr, map->host_vsid, MMU_SEGSIZE_256M); - kvm_set_pfn_accessed(pfn); if (!orig_pte->may_write || !writable) rflags |= PP_RXRX; - else { + else mark_page_dirty(vcpu->kvm, gfn); - kvm_set_pfn_dirty(pfn); - } if (!orig_pte->may_execute) rflags |= HPTE_R_N;
@@ -202,8 +199,11 @@ int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte, } out_unlock: + if (!orig_pte->may_write || !writable) + kvm_release_pfn_clean(pfn); + else + kvm_release_pfn_dirty(pfn); spin_unlock(&kvm->mmu_lock); - kvm_release_pfn_clean(pfn); if (cpte) kvmppc_mmu_hpte_cache_free(cpte);
--
2.46.0.rc1.232.g9752f9e123-goog