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[PW_SID:1123077] RISC-V: KVM: Optimize hfence request handling for SMP guests #2239

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[PW_SID:1123077] RISC-V: KVM: Optimize hfence request handling for SMP guests #2239

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846d0d6
RISC-V: KVM: Introduce make_xfence_request_nodata for FENCE.I requests
yechao-w Jul 7, 2026
2dd650d
RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request
yechao-w Jul 7, 2026
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46 changes: 35 additions & 11 deletions arch/riscv/kvm/tlb.c
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Original file line number Diff line number Diff line change
Expand Up @@ -325,14 +325,11 @@ void kvm_riscv_hfence_process(struct kvm_vcpu *vcpu)
}
}

static void make_xfence_request(struct kvm *kvm,
unsigned long hbase, unsigned long hmask,
unsigned int req, unsigned int fallback_req,
const struct kvm_riscv_hfence *data)
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;
unsigned int actual_req = req;
DECLARE_BITMAP(vcpu_mask, KVM_MAX_VCPUS);

bitmap_zero(vcpu_mask, KVM_MAX_VCPUS);
Expand All @@ -346,27 +343,54 @@ static void make_xfence_request(struct kvm *kvm,
}

bitmap_set(vcpu_mask, i, 1);
}

kvm_make_vcpus_request_mask(kvm, req, vcpu_mask);
}

if (!data || !data->type)
continue;
static void make_xfence_request(struct kvm *kvm,
unsigned long hbase, unsigned long hmask,
unsigned int req, unsigned int fallback_req,
const struct kvm_riscv_hfence *data)
{
unsigned long i;
struct kvm_vcpu *vcpu;
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) {
if (hbase != -1UL) {
if (vcpu->vcpu_id < hbase ||
vcpu->vcpu_id >= hbase + BITS_PER_LONG)
continue;
if (!(hmask & (1UL << (vcpu->vcpu_id - hbase))))
continue;
}

/*
* Enqueue hfence data to VCPU hfence queue. If we don't
* have space in the VCPU hfence queue then fallback to
* a more conservative hfence request.
*/
if (!vcpu_hfence_enqueue(vcpu, data))
actual_req = fallback_req;
bitmap_set(fallback_req_vcpu_mask, i, 1);
else
bitmap_set(req_vcpu_mask, i, 1);
}

kvm_make_vcpus_request_mask(kvm, actual_req, vcpu_mask);
kvm_make_vcpus_request_mask(kvm, req, req_vcpu_mask);
kvm_make_vcpus_request_mask(kvm, fallback_req, fallback_req_vcpu_mask);
}

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,
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