[PATCH v12 43/84] KVM: Add kvm_faultin_pfn() to specifically service guest page faults
From: Sean Christopherson <seanjc@google.com>
Date: 2024-07-26 23:54:07
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
Add a new dedicated API, kvm_faultin_pfn(), for servicing guest page faults, i.e. for getting pages/pfns that will be mapped into the guest via an mmu_notifier-protected KVM MMU. Keep struct kvm_follow_pfn buried in internal code, as having __kvm_faultin_pfn() take "out" params is actually cleaner for several architectures, e.g. it allows the caller to have its own "page fault" structure without having to marshal data to/from kvm_follow_pfn. Long term, common KVM would ideally provide a kvm_page_fault structure, a la x86's struct of the same name. But all architectures need to be converted to a common API before that can happen. Signed-off-by: Sean Christopherson <seanjc@google.com> --- include/linux/kvm_host.h | 11 +++++++++++ virt/kvm/kvm_main.c | 22 ++++++++++++++++++++++ 2 files changed, 33 insertions(+)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ef0277b77375..e0548ae92659 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h@@ -1217,6 +1217,17 @@ void kvm_release_page_clean(struct page *page); void kvm_release_page_dirty(struct page *page); kvm_pfn_t kvm_lookup_pfn(struct kvm *kvm, gfn_t gfn); +kvm_pfn_t __kvm_faultin_pfn(const struct kvm_memory_slot *slot, gfn_t gfn, + unsigned int foll, bool *writable, + struct page **refcounted_page); + +static inline kvm_pfn_t kvm_faultin_pfn(struct kvm_vcpu *vcpu, gfn_t gfn, + bool write, bool *writable, + struct page **refcounted_page) +{ + return __kvm_faultin_pfn(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn, + write ? FOLL_WRITE : 0, writable, refcounted_page); +} kvm_pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn); kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ad84dab8c5dc..6dc448602751 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c@@ -3134,6 +3134,28 @@ kvm_pfn_t kvm_lookup_pfn(struct kvm *kvm, gfn_t gfn) return pfn; } +kvm_pfn_t __kvm_faultin_pfn(const struct kvm_memory_slot *slot, gfn_t gfn, + unsigned int foll, bool *writable, + struct page **refcounted_page) +{ + struct kvm_follow_pfn kfp = { + .slot = slot, + .gfn = gfn, + .flags = foll, + .map_writable = writable, + .refcounted_page = refcounted_page, + }; + + if (WARN_ON_ONCE(!writable || !refcounted_page)) + return KVM_PFN_ERR_FAULT; + + *writable = false; + *refcounted_page = NULL; + + return kvm_follow_pfn(&kfp); +} +EXPORT_SYMBOL_GPL(__kvm_faultin_pfn); + int kvm_prefetch_pages(struct kvm_memory_slot *slot, gfn_t gfn, struct page **pages, int nr_pages) {
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2.46.0.rc1.232.g9752f9e123-goog