diff mbox series

[v12,11/84] KVM: Rename gfn_to_page_many_atomic() to kvm_prefetch_pages()

Message ID 20240726235234.228822-12-seanjc@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: Stop grabbing references to PFNMAP'd pages | expand

Commit Message

Sean Christopherson July 26, 2024, 11:51 p.m. UTC
Rename gfn_to_page_many_atomic() to kvm_prefetch_pages() to try and
communicate its true purpose, as the "atomic" aspect is essentially a
side effect of the fact that x86 uses the API while holding mmu_lock.
E.g. even if mmu_lock weren't held, KVM wouldn't want to fault-in pages,
as the goal is to opportunistically grab surrounding pages that have
already been accessed and/or dirtied by the host, and to do so quickly.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/mmu/mmu.c         | 2 +-
 arch/x86/kvm/mmu/paging_tmpl.h | 2 +-
 include/linux/kvm_host.h       | 4 ++--
 virt/kvm/kvm_main.c            | 6 +++---
 4 files changed, 7 insertions(+), 7 deletions(-)

Comments

Alex Bennée Aug. 2, 2024, 11:16 a.m. UTC | #1
Sean Christopherson <seanjc@google.com> writes:

> Rename gfn_to_page_many_atomic() to kvm_prefetch_pages() to try and
> communicate its true purpose, as the "atomic" aspect is essentially a
> side effect of the fact that x86 uses the API while holding mmu_lock.

It's never too late to start adding some kdoc annotations to a function
and renaming a kvm_host API call seems like a good time to do it.

> E.g. even if mmu_lock weren't held, KVM wouldn't want to fault-in pages,
> as the goal is to opportunistically grab surrounding pages that have
> already been accessed and/or dirtied by the host, and to do so quickly.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
<snip>

/**
 * kvm_prefetch_pages() - opportunistically grab previously accessed pages
 * @slot: which @kvm_memory_slot the pages are in
 * @gfn: guest frame
 * @pages: array to receives page pointers
 * @nr_pages: number of pages
 *
 * Returns the number of pages actually mapped.
 */

?

>  
> -int gfn_to_page_many_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
> -			    struct page **pages, int nr_pages)
> +int kvm_prefetch_pages(struct kvm_memory_slot *slot, gfn_t gfn,
> +		       struct page **pages, int nr_pages)
>  {
>  	unsigned long addr;
>  	gfn_t entry = 0;
> @@ -3075,7 +3075,7 @@ int gfn_to_page_many_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
>  
>  	return get_user_pages_fast_only(addr, nr_pages, FOLL_WRITE, pages);
>  }
> -EXPORT_SYMBOL_GPL(gfn_to_page_many_atomic);
> +EXPORT_SYMBOL_GPL(kvm_prefetch_pages);
>  
>  /*
>   * Do not use this helper unless you are absolutely certain the gfn _must_ be
diff mbox series

Patch

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index b7642f1f993f..c1914f02c5e1 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2912,7 +2912,7 @@  static int direct_pte_prefetch_many(struct kvm_vcpu *vcpu,
 	if (!slot)
 		return -1;
 
-	ret = gfn_to_page_many_atomic(slot, gfn, pages, end - start);
+	ret = kvm_prefetch_pages(slot, gfn, pages, end - start);
 	if (ret <= 0)
 		return -1;
 
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 6b215a932158..bc801d454f41 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -549,7 +549,7 @@  FNAME(prefetch_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 	if (!slot)
 		return false;
 
-	if (gfn_to_page_many_atomic(slot, gfn, &page, 1) != 1)
+	if (kvm_prefetch_pages(slot, gfn, &page, 1) != 1)
 		return false;
 
 	mmu_set_spte(vcpu, slot, spte, pte_access, gfn, page_to_pfn(page), NULL);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c5d39a337aa3..79fed9fea638 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1192,8 +1192,8 @@  void kvm_arch_flush_shadow_all(struct kvm *kvm);
 void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
 				   struct kvm_memory_slot *slot);
 
-int gfn_to_page_many_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
-			    struct page **pages, int nr_pages);
+int kvm_prefetch_pages(struct kvm_memory_slot *slot, gfn_t gfn,
+		       struct page **pages, int nr_pages);
 
 struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn);
 unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 656e931ac39e..803299778cf8 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3060,8 +3060,8 @@  kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_pfn);
 
-int gfn_to_page_many_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
-			    struct page **pages, int nr_pages)
+int kvm_prefetch_pages(struct kvm_memory_slot *slot, gfn_t gfn,
+		       struct page **pages, int nr_pages)
 {
 	unsigned long addr;
 	gfn_t entry = 0;
@@ -3075,7 +3075,7 @@  int gfn_to_page_many_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
 
 	return get_user_pages_fast_only(addr, nr_pages, FOLL_WRITE, pages);
 }
-EXPORT_SYMBOL_GPL(gfn_to_page_many_atomic);
+EXPORT_SYMBOL_GPL(kvm_prefetch_pages);
 
 /*
  * Do not use this helper unless you are absolutely certain the gfn _must_ be