From ed54fdb460a6e81d5f8f38388d1f10b385dd4a58 Mon Sep 17 00:00:00 2001 From: Xie Bo Date: Mon, 10 Aug 2026 13:15:43 +0800 Subject: [PATCH] RISC-V: KVM: Release unused page after MMU invalidation If an MMU invalidation races with a G-stage fault, the fault handler skips installing the page but leaves ret set to zero. As a result, kvm_release_faultin_page() treats the page as used and can unnecessarily mark it dirty. Track the invalidation retry separately and release the page as unused, while preserving the existing return value so that the vCPU retries the fault. Fixes: 2ed90cb0938a ("KVM: RISC-V: Retry fault if vma_lookup() results become invalid") Cc: stable@vger.kernel.org Signed-off-by: Xie Bo Reviewed-by: Anup Patel Link: https://lore.kernel.org/r/20260810051544.3953925-2-xb@ultrarisc.com Signed-off-by: Anup Patel --- arch/riscv/kvm/mmu.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c index 6035b5ec9503..d189fd58d7bf 100644 --- a/arch/riscv/kvm/mmu.c +++ b/arch/riscv/kvm/mmu.c @@ -627,6 +627,7 @@ int kvm_riscv_mmu_map(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot, int ret; kvm_pfn_t hfn; bool is_hugetlb; + bool unused = false; bool writable; unsigned int vma_pageshift; gfn_t gfn = gpa >> PAGE_SHIFT; @@ -719,8 +720,10 @@ int kvm_riscv_mmu_map(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot, write_lock(&kvm->mmu_lock); - if (mmu_invalidate_retry(kvm, mmu_seq)) + if (mmu_invalidate_retry(kvm, mmu_seq)) { + unused = true; goto out_unlock; + } /* * Check if we are backed by a THP and thus use block mapping if @@ -743,7 +746,8 @@ int kvm_riscv_mmu_map(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot, kvm_err("Failed to map in G-stage\n"); out_unlock: - kvm_release_faultin_page(kvm, page, ret && ret != -EEXIST, writable); + kvm_release_faultin_page(kvm, page, + unused || (ret && ret != -EEXIST), writable); write_unlock(&kvm->mmu_lock); return ret; }