[PATCH v3 2/2] RISC-V: KVM: Introduce make_xfence_request_nodata for FENCE.I requests

[Wang Yechao]

FENCE.I does not need hfence data, but it currently goes through the
generic make_xfence_request() path with NULL data, incurring unnecessary
per-VCPU checks.

Split out a separate make_xfence_request_nodata() function to handle
FENCE.I directly, and move the data validity check to the top of the
generic function to avoid redundant checks.

Signed-off-by: Wang Yechao <wang.yechao255@xxxxxxxxxx>
---
 arch/riscv/kvm/tlb.c | 34 +++++++++++++++++++++++++++-------
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/arch/riscv/kvm/tlb.c b/arch/riscv/kvm/tlb.c
index c54522decaa64..fd445e9fa3f94 100644
--- a/arch/riscv/kvm/tlb.c
+++ b/arch/riscv/kvm/tlb.c
@@ -325,6 +325,29 @@ void kvm_riscv_hfence_process(struct kvm_vcpu *vcpu)
 	}
 }
 
+static void make_xfence_request_nodata(struct kvm *kvm, unsigned long hbase,
+				       unsigned long hmask, unsigned int req)
+{
+	unsigned long i;
+	struct kvm_vcpu *vcpu;
+	DECLARE_BITMAP(vcpu_mask, KVM_MAX_VCPUS);
+
+	bitmap_zero(vcpu_mask, KVM_MAX_VCPUS);
+	kvm_for_each_vcpu(i, vcpu, kvm) {
+		if (hbase != -1UL) {
+			if (vcpu->vcpu_id < hbase ||
+				vcpu->vcpu_id >= hbase + BITS_PER_LONG)
+				continue;
+			if (!(hmask & (1UL << (vcpu->vcpu_id - hbase))))
+				continue;
+		}
+
+		bitmap_set(vcpu_mask, i, 1);
+	}
+
+	kvm_make_vcpus_request_mask(kvm, req, vcpu_mask);
+}
+
 static void make_xfence_request(struct kvm *kvm,
 				unsigned long hbase, unsigned long hmask,
 				unsigned int req, unsigned int fallback_req,
@@ -335,6 +358,9 @@ static void make_xfence_request(struct kvm *kvm,
 	DECLARE_BITMAP(req_vcpu_mask, KVM_MAX_VCPUS);
 	DECLARE_BITMAP(fallback_req_vcpu_mask, KVM_MAX_VCPUS);
 
+	if (!data || !data->type)
+		return;
+
 	bitmap_zero(req_vcpu_mask, KVM_MAX_VCPUS);
 	bitmap_zero(fallback_req_vcpu_mask, KVM_MAX_VCPUS);
 	kvm_for_each_vcpu(i, vcpu, kvm) {
@@ -346,11 +372,6 @@ static void make_xfence_request(struct kvm *kvm,
 				continue;
 		}
 
-		if (!data || !data->type) {
-			bitmap_set(req_vcpu_mask, i, 1);
-			continue;
-		}
-
 		/*
 		 * Enqueue hfence data to VCPU hfence queue. If we don't
 		 * have space in the VCPU hfence queue then fallback to
@@ -369,8 +390,7 @@ static void make_xfence_request(struct kvm *kvm,
 void kvm_riscv_fence_i(struct kvm *kvm,
 		       unsigned long hbase, unsigned long hmask)
 {
-	make_xfence_request(kvm, hbase, hmask, KVM_REQ_FENCE_I,
-			    KVM_REQ_FENCE_I, NULL);
+	make_xfence_request_nodata(kvm, hbase, hmask, KVM_REQ_FENCE_I);
 }
 
 void kvm_riscv_hfence_gvma_vmid_gpa(struct kvm *kvm,
-- 
2.39.3