[PATCH v13 66/85] KVM: LoongArch: Mark "struct page" pfns accessed only in "slow" page fault path

Sean Christopherson
2024-10-10T21:46:48Z

Mark pages accessed only in the slow path, before dropping mmu_lock when
faulting in guest memory so that LoongArch can convert to
kvm_release_faultin_page() without tripping its lockdep assertion on
mmu_lock being held.

Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/loongarch/kvm/mmu.c | 20 ++------------------
1 file changed, 2 insertions(+), 18 deletions(-)

diff --git a/arch/loongarch/kvm/mmu.c b/arch/loongarch/kvm/mmu.c
index cc2a5f289b14..ed43504c5c7e 100644
--- a/arch/loongarch/kvm/mmu.c
+++ b/arch/loongarch/kvm/mmu.c
@@ -552,12 +552,10 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool write)
{
int ret = 0;
- kvm_pfn_t pfn = 0;
kvm_pte_t *ptep, changed, new;
gfn_t gfn = gpa >> PAGE_SHIFT;
struct kvm *kvm = vcpu->kvm;
struct kvm_memory_slot *slot;
- struct page *page;

spin_lock(&kvm->mmu_lock);

@@ -570,8 +568,6 @@ static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool writ

/* Track access to pages marked old */
new = kvm_pte_mkyoung(*ptep);
- /* call kvm_set_pfn_accessed() after unlock */
-
if (write && !kvm_pte_dirty(new)) {
if (!kvm_pte_write(new)) {
ret = -EFAULT;
@@ -595,23 +591,11 @@ static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool writ
}

changed = new ^ (*ptep);
- if (changed) {
+ if (changed)
kvm_set_pte(ptep, new);
- pfn = kvm_pte_pfn(new);
- page = kvm_pfn_to_refcounted_page(pfn);
- if (page)
- get_page(page);
- }
+
spin_unlock(&kvm->mmu_lock);

- if (changed) {
- if (kvm_pte_young(changed))
- kvm_set_pfn_accessed(pfn);
-
- if (page)
- put_page(page);
- }
-
if (kvm_pte_dirty(changed))
mark_page_dirty(kvm, gfn);