KVM: RISC-V: Mark "struct page" pfns dirty iff a stage-2 PTE is installed

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>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-58-seanjc@google.com>

diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index b63650f9b966ac8e9655ed4de54aee67a0914bf4..06aa5a0d056d47fbbd5f6bcf1c626488b7f78fd9 100644 (file)
--- 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);