[PATCH v13 69/85] KVM: MIPS: Mark "struct page" pfns dirty only in "slow" page fault path
From: Sean Christopherson <seanjc@google.com>
Date: 2024-10-10 18:27:18
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-mips, linux-riscv, lkml, loongarch
Subsystem:
kernel virtual machine for mips (kvm/mips), mips, the rest · Maintainers:
Huacai Chen, Thomas Bogendoerfer, Linus Torvalds
Mark pages/folios dirty only the slow page fault path, i.e. only when mmu_lock is held and the operation is mmu_notifier-protected, as 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. Link: https://lore.kernel.org/all/cover.1683044162.git.lstoakes@gmail.com (local) Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/mips/kvm/mmu.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
index c17157e700c0..4da9ce4eb54d 100644
--- a/arch/mips/kvm/mmu.c
+++ b/arch/mips/kvm/mmu.c@@ -514,7 +514,6 @@ static int _kvm_mips_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, set_pte(ptep, pte_mkdirty(*ptep)); pfn = pte_pfn(*ptep); mark_page_dirty(kvm, gfn); - kvm_set_pfn_dirty(pfn); } if (out_entry)
@@ -628,7 +627,6 @@ static int kvm_mips_map_page(struct kvm_vcpu *vcpu, unsigned long gpa, if (write_fault) { prot_bits |= __WRITEABLE; mark_page_dirty(kvm, gfn); - kvm_set_pfn_dirty(pfn); } } entry = pfn_pte(pfn, __pgprot(prot_bits));
@@ -642,6 +640,9 @@ static int kvm_mips_map_page(struct kvm_vcpu *vcpu, unsigned long gpa, if (out_buddy) *out_buddy = *ptep_buddy(ptep); + if (writeable) + kvm_set_pfn_dirty(pfn); + spin_unlock(&kvm->mmu_lock); kvm_release_pfn_clean(pfn); kvm_set_pfn_accessed(pfn);
--
2.47.0.rc1.288.g06298d1525-goog