Commit c36b7150 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

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: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c583eed6

arch/x86/kvm/mmu/mmu.c

+3 −6
Original line number Diff line number Diff line
@@ -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)

include/linux/kvm_host.h

+6 −0
Original line number Diff line number Diff line
@@ -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);

virt/kvm/kvm_main.c

+1 −5
Original line number Diff line number Diff line
@@ -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);

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