KVM: Drop @atomic param from gfn=>pfn and hva=>pfn APIs

Drop @atomic from the myriad "to_pfn" APIs now that all callers pass
"false", and remove a comment blurb about KVM running only the "GUP fast"
part in atomic context.

No functional change intended.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-13-seanjc@google.com>

3 files changed, 11 insertions, 28 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index aa7ae0f0f90e..c7506eb23086 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2756,8 +2756,7 @@ static inline int check_user_page_hwpoison(unsigned long addr)
 
 /*
  * The fast path to get the writable pfn which will be stored in @pfn,
- * true indicates success, otherwise false is returned.  It's also the
- * only part that runs if we can in atomic context.
+ * true indicates success, otherwise false is returned.
  */
 static bool hva_to_pfn_fast(unsigned long addr, bool write_fault,
 			    bool *writable, kvm_pfn_t *pfn)
@@ -2922,7 +2921,6 @@ out:
 /*
  * Pin guest page in memory and return its pfn.
  * @addr: host virtual address which maps memory to the guest
- * @atomic: whether this function is forbidden from sleeping
  * @interruptible: whether the process can be interrupted by non-fatal signals
  * @async: whether this function need to wait IO complete if the
  *         host page is not in the memory
@@ -2934,22 +2932,16 @@ out:
  * 2): @write_fault = false && @writable, @writable will tell the caller
  *     whether the mapping is writable.
  */
-kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool interruptible,
-		     bool *async, bool write_fault, bool *writable)
+kvm_pfn_t hva_to_pfn(unsigned long addr, bool interruptible, bool *async,
+		     bool write_fault, bool *writable)
 {
 	struct vm_area_struct *vma;
 	kvm_pfn_t pfn;
 	int npages, r;
 
-	/* we can do it either atomically or asynchronously, not both */
-	BUG_ON(atomic && async);
-
 	if (hva_to_pfn_fast(addr, write_fault, writable, &pfn))
 		return pfn;
 
-	if (atomic)
-		return KVM_PFN_ERR_FAULT;
-
 	npages = hva_to_pfn_slow(addr, async, write_fault, interruptible,
 				 writable, &pfn);
 	if (npages == 1)
@@ -2986,7 +2978,7 @@ exit:
 }
 
 kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn,
-			       bool atomic, bool interruptible, bool *async,
+			       bool interruptible, bool *async,
 			       bool write_fault, bool *writable, hva_t *hva)
 {
 	unsigned long addr = __gfn_to_hva_many(slot, gfn, NULL, write_fault);
@@ -3008,33 +3000,24 @@ kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn,
 		writable = NULL;
 	}
 
-	return hva_to_pfn(addr, atomic, interruptible, async, write_fault,
-			  writable);
+	return hva_to_pfn(addr, interruptible, async, write_fault, writable);
 }
 EXPORT_SYMBOL_GPL(__gfn_to_pfn_memslot);
 
 kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
 		      bool *writable)
 {
-	return __gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn, false, false,
-				    NULL, write_fault, writable, NULL);
+	return __gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn, false, NULL,
+				    write_fault, writable, NULL);
 }
 EXPORT_SYMBOL_GPL(gfn_to_pfn_prot);
 
 kvm_pfn_t gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn)
 {
-	return __gfn_to_pfn_memslot(slot, gfn, false, false, NULL, true,
-				    NULL, NULL);
+	return __gfn_to_pfn_memslot(slot, gfn, false, NULL, true, NULL, NULL);
 }
 EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot);
 
-kvm_pfn_t gfn_to_pfn_memslot_atomic(const struct kvm_memory_slot *slot, gfn_t gfn)
-{
-	return __gfn_to_pfn_memslot(slot, gfn, true, false, NULL, true,
-				    NULL, NULL);
-}
-EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot_atomic);
-
 kvm_pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
 {
 	return gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn);
diff --git a/virt/kvm/kvm_mm.h b/virt/kvm/kvm_mm.h
index 715f19669d01..a3fa86f60d6c 100644
--- a/virt/kvm/kvm_mm.h
+++ b/virt/kvm/kvm_mm.h
@@ -20,8 +20,8 @@
 #define KVM_MMU_UNLOCK(kvm)		spin_unlock(&(kvm)->mmu_lock)
 #endif /* KVM_HAVE_MMU_RWLOCK */
 
-kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool interruptible,
-		     bool *async, bool write_fault, bool *writable);
+kvm_pfn_t hva_to_pfn(unsigned long addr, bool interruptible, bool *async,
+		     bool write_fault, bool *writable);
 
 #ifdef CONFIG_HAVE_KVM_PFNCACHE
 void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm,
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index f0039efb9e1e..58c706a610e5 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -198,7 +198,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc)
 		}
 
 		/* We always request a writeable mapping */
-		new_pfn = hva_to_pfn(gpc->uhva, false, false, NULL, true, NULL);
+		new_pfn = hva_to_pfn(gpc->uhva, false, NULL, true, NULL);
 		if (is_error_noslot_pfn(new_pfn))
 			goto out_error;