KVM: Store immutable gfn_to_pfn_cache properties

Move the assignment of immutable properties @kvm, @vcpu, and @usage to
the initializer.  Make _activate() and _deactivate() use stored values.

Note, @len is also effectively immutable for most cases, but not in the
case of the Xen runstate cache, which may be split across two pages and
the length of the first segment will depend on its address.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
[sean: handle @len in a separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>
[dwmw2: acknowledge that @len can actually change for some use cases]
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>

1 files changed, 18 insertions, 19 deletions

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 8f874a964313..73ded328f9dc 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1260,18 +1260,7 @@ void kvm_vcpu_mark_page_dirty(struct kvm_vcpu *vcpu, gfn_t gfn);
  * kvm_gpc_init - initialize gfn_to_pfn_cache.
  *
  * @gpc:	   struct gfn_to_pfn_cache object.
- *
- * This sets up a gfn_to_pfn_cache by initializing locks.  Note, the cache must
- * be zero-allocated (or zeroed by the caller before init).
- */
-void kvm_gpc_init(struct gfn_to_pfn_cache *gpc);
-
-/**
- * kvm_gpc_activate - prepare a cached kernel mapping and HPA for a given guest
- *                    physical address.
- *
  * @kvm:	   pointer to kvm instance.
- * @gpc:	   struct gfn_to_pfn_cache object.
  * @vcpu:	   vCPU to be used for marking pages dirty and to be woken on
  *		   invalidation.
  * @usage:	   indicates if the resulting host physical PFN is used while
@@ -1280,20 +1269,31 @@ void kvm_gpc_init(struct gfn_to_pfn_cache *gpc);
  *		   changes!---will also force @vcpu to exit the guest and
  *		   refresh the cache); and/or if the PFN used directly
  *		   by KVM (and thus needs a kernel virtual mapping).
+ *
+ * This sets up a gfn_to_pfn_cache by initializing locks and assigning the
+ * immutable attributes.  Note, the cache must be zero-allocated (or zeroed by
+ * the caller before init).
+ */
+void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm,
+		  struct kvm_vcpu *vcpu, enum pfn_cache_usage usage);
+
+/**
+ * kvm_gpc_activate - prepare a cached kernel mapping and HPA for a given guest
+ *                    physical address.
+ *
+ * @gpc:	   struct gfn_to_pfn_cache object.
  * @gpa:	   guest physical address to map.
  * @len:	   sanity check; the range being access must fit a single page.
  *
  * @return:	   0 for success.
  *		   -EINVAL for a mapping which would cross a page boundary.
- *                 -EFAULT for an untranslatable guest physical address.
+ *		   -EFAULT for an untranslatable guest physical address.
  *
- * This primes a gfn_to_pfn_cache and links it into the @kvm's list for
+ * This primes a gfn_to_pfn_cache and links it into the @gpc->kvm's list for
  * invalidations to be processed.  Callers are required to use kvm_gpc_check()
  * to ensure that the cache is valid before accessing the target page.
  */
-int kvm_gpc_activate(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
-		     struct kvm_vcpu *vcpu, enum pfn_cache_usage usage,
-		     gpa_t gpa, unsigned long len);
+int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len);
 
 /**
  * kvm_gpc_check - check validity of a gfn_to_pfn_cache.
@@ -1352,13 +1352,12 @@ void kvm_gpc_unmap(struct kvm *kvm, struct gfn_to_pfn_cache *gpc);
 /**
  * kvm_gpc_deactivate - deactivate and unlink a gfn_to_pfn_cache.
  *
- * @kvm:	   pointer to kvm instance.
  * @gpc:	   struct gfn_to_pfn_cache object.
  *
- * This removes a cache from the @kvm's list to be processed on MMU notifier
+ * This removes a cache from the VM's list to be processed on MMU notifier
  * invocation.
  */
-void kvm_gpc_deactivate(struct kvm *kvm, struct gfn_to_pfn_cache *gpc);
+void kvm_gpc_deactivate(struct gfn_to_pfn_cache *gpc);
 
 void kvm_sigset_activate(struct kvm_vcpu *vcpu);
 void kvm_sigset_deactivate(struct kvm_vcpu *vcpu);