KVM: x86/mmu: Avoid an extra memslot lookup in try_async_pf() for L2

Create a new function kvm_is_visible_memslot() and use it from
kvm_is_visible_gfn(); use the new function in try_async_pf() too,
to avoid an extra memslot lookup.

Opportunistically squish a multi-line comment into a single-line comment.

Note, the end result, KVM_PFN_NOSLOT, is unchanged.

Cc: Jim Mattson <jmattson@google.com>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index b67046f..e618472 100644 (file)
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4082,19 +4082,16 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn,
                         gpa_t cr2_or_gpa, kvm_pfn_t *pfn, bool write,
                         bool *writable)
 {
-       struct kvm_memory_slot *slot;
+       struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
        bool async;
 
-       /*
-        * Don't expose private memslots to L2.
-        */
-       if (is_guest_mode(vcpu) && !kvm_is_visible_gfn(vcpu->kvm, gfn)) {
+       /* Don't expose private memslots to L2. */
+       if (is_guest_mode(vcpu) && !kvm_is_visible_memslot(slot)) {
                *pfn = KVM_PFN_NOSLOT;
                *writable = false;
                return false;
        }
 
-       slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
        async = false;
        *pfn = __gfn_to_pfn_memslot(slot, gfn, false, &async, write, writable);
        if (!async)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 658215f..7d4f1eb 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1357,6 +1357,12 @@ static inline void kvm_vcpu_set_dy_eligible(struct kvm_vcpu *vcpu, bool val)
 }
 #endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */
 
+static inline bool kvm_is_visible_memslot(struct kvm_memory_slot *memslot)
+{
+       return (memslot && memslot->id < KVM_USER_MEM_SLOTS &&
+               !(memslot->flags & KVM_MEMSLOT_INVALID));
+}
+
 struct kvm_vcpu *kvm_get_running_vcpu(void);
 struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void);
 

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index da8fd45..8aa577d 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1607,11 +1607,7 @@ bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
 {
        struct kvm_memory_slot *memslot = gfn_to_memslot(kvm, gfn);
 
-       if (!memslot || memslot->id >= KVM_USER_MEM_SLOTS ||
-             memslot->flags & KVM_MEMSLOT_INVALID)
-               return false;
-
-       return true;
+       return kvm_is_visible_memslot(memslot);
 }
 EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);