[PATCH v12 27/84] KVM: pfncache: Precisely track refcounted pages
From: Sean Christopherson <seanjc@google.com>
Date: 2024-07-26 23:53:34
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-mips, linux-riscv, lkml, loongarch
Subsystem:
kernel virtual machine (kvm), the rest · Maintainers:
Paolo Bonzini, Linus Torvalds
Track refcounted struct page memory using kvm_follow_pfn.refcounted_page instead of relying on kvm_release_pfn_clean() to correctly detect that the pfn is associated with a struct page. Signed-off-by: Sean Christopherson <seanjc@google.com> --- virt/kvm/pfncache.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index 067daf9ad6ef..728d2c1b488a 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c@@ -159,11 +159,14 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc) kvm_pfn_t new_pfn = KVM_PFN_ERR_FAULT; void *new_khva = NULL; unsigned long mmu_seq; + struct page *page; + struct kvm_follow_pfn kfp = { .slot = gpc->memslot, .gfn = gpa_to_gfn(gpc->gpa), .flags = FOLL_WRITE, .hva = gpc->uhva, + .refcounted_page = &page, }; lockdep_assert_held(&gpc->refresh_lock);
@@ -198,7 +201,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc) if (new_khva != old_khva) gpc_unmap(new_pfn, new_khva); - kvm_release_pfn_clean(new_pfn); + kvm_release_page_unused(page); cond_resched(); }
@@ -218,7 +221,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc) new_khva = gpc_map(new_pfn); if (!new_khva) { - kvm_release_pfn_clean(new_pfn); + kvm_release_page_unused(page); goto out_error; }
@@ -236,11 +239,11 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc) gpc->khva = new_khva + offset_in_page(gpc->uhva); /* - * Put the reference to the _new_ pfn. The pfn is now tracked by the + * Put the reference to the _new_ page. The page is now tracked by the * cache and can be safely migrated, swapped, etc... as the cache will * invalidate any mappings in response to relevant mmu_notifier events. */ - kvm_release_pfn_clean(new_pfn); + kvm_release_page_clean(page); return 0;
--
2.46.0.rc1.232.g9752f9e123-goog