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Subject[PATCH v3 4/6] KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE} implementation
Date
Implement HvFlushVirtualAddress{List,Space} hypercalls in a simplistic way:
do full TLB flush with KVM_REQ_TLB_FLUSH and kick vCPUs which are currently
IN_GUEST_MODE.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/hyperv.c | 74 ++++++++++++++++++++++++++++++++++++++++-
arch/x86/kvm/trace.h | 24 +++++++++++++
3 files changed, 98 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c25775fad4ed..9ce1fb2b6af3 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -476,6 +476,7 @@ struct kvm_vcpu_hv {
struct kvm_hyperv_exit exit;
struct kvm_vcpu_hv_stimer stimer[HV_SYNIC_STIMER_COUNT];
DECLARE_BITMAP(stimer_pending_bitmap, HV_SYNIC_STIMER_COUNT);
+ cpumask_t tlb_lush;
};

struct kvm_vcpu_arch {
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 67788d358200..fa26af1e8b7c 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1242,6 +1242,65 @@ int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
return kvm_hv_get_msr(vcpu, msr, pdata);
}

+static void ack_flush(void *_completed)
+{
+}
+
+static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
+ u16 rep_cnt)
+{
+ struct kvm *kvm = current_vcpu->kvm;
+ struct kvm_vcpu_hv *hv_current = &current_vcpu->arch.hyperv;
+ struct hv_tlb_flush flush;
+ struct kvm_vcpu *vcpu;
+ int i, cpu, me;
+
+ if (unlikely(kvm_read_guest(kvm, ingpa, &flush, sizeof(flush))))
+ return HV_STATUS_INVALID_HYPERCALL_INPUT;
+
+ trace_kvm_hv_flush_tlb(flush.processor_mask, flush.address_space,
+ flush.flags);
+
+ cpumask_clear(&hv_current->tlb_lush);
+
+ me = get_cpu();
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ struct kvm_vcpu_hv *hv = &vcpu->arch.hyperv;
+
+ if (!(flush.flags & HV_FLUSH_ALL_PROCESSORS) &&
+ !(flush.processor_mask & BIT_ULL(hv->vp_index)))
+ continue;
+
+ /*
+ * vcpu->arch.cr3 may not be up-to-date for running vCPUs so we
+ * can't analyze it here, flush TLB regardless of the specified
+ * address space.
+ */
+ kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
+
+ /*
+ * It is possible that vCPU will migrate and we will kick wrong
+ * CPU but vCPU's TLB will anyway be flushed upon migration as
+ * we already made KVM_REQ_TLB_FLUSH request.
+ */
+ cpu = vcpu->cpu;
+ if (cpu != -1 && cpu != me && cpu_online(cpu) &&
+ kvm_arch_vcpu_should_kick(vcpu))
+ cpumask_set_cpu(cpu, &hv_current->tlb_lush);
+ }
+
+ if (!cpumask_empty(&hv_current->tlb_lush))
+ smp_call_function_many(&hv_current->tlb_lush, ack_flush,
+ NULL, true);
+
+ put_cpu();
+
+ /* We always do full TLB flush, set rep_done = rep_cnt. */
+ return (u64)HV_STATUS_SUCCESS |
+ ((u64)rep_cnt << HV_HYPERCALL_REP_COMP_OFFSET);
+}
+
bool kvm_hv_hypercall_enabled(struct kvm *kvm)
{
return READ_ONCE(kvm->arch.hyperv.hv_hypercall) & HV_X64_MSR_HYPERCALL_ENABLE;
@@ -1377,12 +1436,25 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
vcpu->arch.complete_userspace_io =
kvm_hv_hypercall_complete_userspace;
return 0;
+ case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
+ if (unlikely(fast || !rep_cnt || rep_idx)) {
+ ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+ break;
+ }
+ ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt);
+ break;
+ case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
+ if (unlikely(fast || rep)) {
+ ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+ break;
+ }
+ ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt);
+ break;
default:
ret = HV_STATUS_INVALID_HYPERCALL_CODE;
break;
}

-set_result:
kvm_hv_hypercall_set_result(vcpu, ret);
return 1;
}
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 9807c314c478..47a4fd758743 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -1367,6 +1367,30 @@ TRACE_EVENT(kvm_hv_timer_state,
__entry->vcpu_id,
__entry->hv_timer_in_use)
);
+
+/*
+ * Tracepoint for kvm_hv_flush_tlb.
+ */
+TRACE_EVENT(kvm_hv_flush_tlb,
+ TP_PROTO(u64 processor_mask, u64 address_space, u64 flags),
+ TP_ARGS(processor_mask, address_space, flags),
+
+ TP_STRUCT__entry(
+ __field(u64, processor_mask)
+ __field(u64, address_space)
+ __field(u64, flags)
+ ),
+
+ TP_fast_assign(
+ __entry->processor_mask = processor_mask;
+ __entry->address_space = address_space;
+ __entry->flags = flags;
+ ),
+
+ TP_printk("processor_mask 0x%llx address_space 0x%llx flags 0x%llx",
+ __entry->processor_mask, __entry->address_space,
+ __entry->flags)
+);
#endif /* _TRACE_KVM_H */

#undef TRACE_INCLUDE_PATH
--
2.14.3
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