From: Fuad Tabba <tabba@google.com>
Date: Fri, 6 Mar 2026 14:02:30 +0000 (+0000)
Subject: KVM: arm64: Optimize early exit checks in kvm_s2_fault_pin_pfn()
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3456943e8786d56aa2bd3f99e9ad2d735a9879c8;p=thirdparty%2Fkernel%2Fstable.git

KVM: arm64: Optimize early exit checks in kvm_s2_fault_pin_pfn()

Optimize the early exit checks in kvm_s2_fault_pin_pfn by grouping all
error responses under the generic is_error_noslot_pfn check first,
avoiding unnecessary branches in the hot path.

Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index fe942be061cb..74c512839e81 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1791,12 +1791,13 @@ static int kvm_s2_fault_pin_pfn(struct kvm_s2_fault *fault)
 	fault->pfn = __kvm_faultin_pfn(fault->memslot, fault->gfn,
 				       fault->write_fault ? FOLL_WRITE : 0,
 				       &fault->writable, &fault->page);
-	if (fault->pfn == KVM_PFN_ERR_HWPOISON) {
-		kvm_send_hwpoison_signal(fault->hva, __ffs(fault->vma_pagesize));
-		return 0;
-	}
-	if (is_error_noslot_pfn(fault->pfn))
+	if (unlikely(is_error_noslot_pfn(fault->pfn))) {
+		if (fault->pfn == KVM_PFN_ERR_HWPOISON) {
+			kvm_send_hwpoison_signal(fault->hva, __ffs(fault->vma_pagesize));
+			return 0;
+		}
 		return -EFAULT;
+	}
 
 	return 1;
 }