[PATCH v13 57/85] KVM: RISC-V: Mark "struct page" pfns dirty iff a stage-2 PTE is installed

Sean Christopherson
2024-10-10T21:46:34Z

Don't mark pages dirty if KVM bails from the page fault handler without
installing a stage-2 mapping, i.e. if the page is guaranteed to not be
written by the guest.

In addition to being a (very) minor fix, this paves the way for converting
RISC-V to use kvm_release_faultin_page().

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 | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index b63650f9b966..06aa5a0d056d 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -669,7 +669,6 @@ int kvm_riscv_gstage_map(struct kvm_vcpu *vcpu,
goto out_unlock;

if (writable) {
- kvm_set_pfn_dirty(hfn);
mark_page_dirty(kvm, gfn);
ret = gstage_map_page(kvm, pcache, gpa, hfn << PAGE_SHIFT,
vma_pagesize, false, true);
@@ -682,6 +681,9 @@ int kvm_riscv_gstage_map(struct kvm_vcpu *vcpu,
kvm_err("Failed to map in G-stage\n");

out_unlock:
+ if ((!ret || ret == -EEXIST) && writable)
+ kvm_set_pfn_dirty(hfn);
+
spin_unlock(&kvm->mmu_lock);
kvm_set_pfn_accessed(hfn);
kvm_release_pfn_clean(hfn);