From c58a318f6090efe06e6702b8882e2026f44f620e Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Tue, 1 Nov 2022 15:54:01 +0100 Subject: [PATCH] KVM: x86: hyper-v: L2 TLB flush Handle L2 TLB flush requests by going through all vCPUs and checking whether there are vCPUs running the same VM_ID with a VP_ID specified in the requests. Perform synthetic exit to L2 upon finish. Note, while checking VM_ID/VP_ID of running vCPUs seem to be a bit racy, we count on the fact that KVM flushes the whole L2 VPID upon transition. Also, KVM_REQ_HV_TLB_FLUSH request needs to be done upon transition between L1 and L2 to make sure all pending requests are always processed. For the reference, Hyper-V TLFS refers to the feature as "Direct Virtual Flush". Note, nVMX/nSVM code does not handle VMCALL/VMMCALL from L2 yet. Reviewed-by: Sean Christopherson Signed-off-by: Vitaly Kuznetsov Signed-off-by: Paolo Bonzini Message-Id: <20221101145426.251680-24-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/hyperv.c | 80 ++++++++++++++++++++++++++++++++++++++++++--------- arch/x86/kvm/hyperv.h | 3 -- arch/x86/kvm/trace.h | 21 ++++++++------ 3 files changed, 80 insertions(+), 24 deletions(-) diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 058e145..3715a6f 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -34,6 +34,7 @@ #include #include +#include #include #include "trace.h" @@ -1832,18 +1833,16 @@ static int kvm_hv_get_tlb_flush_entries(struct kvm *kvm, struct kvm_hv_hcall *hc entries, consumed_xmm_halves, offset); } -static void hv_tlb_flush_enqueue(struct kvm_vcpu *vcpu, u64 *entries, int count) +static void hv_tlb_flush_enqueue(struct kvm_vcpu *vcpu, + struct kvm_vcpu_hv_tlb_flush_fifo *tlb_flush_fifo, + u64 *entries, int count) { - struct kvm_vcpu_hv_tlb_flush_fifo *tlb_flush_fifo; struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu); u64 flush_all_entry = KVM_HV_TLB_FLUSHALL_ENTRY; if (!hv_vcpu) return; - /* kvm_hv_flush_tlb() is not ready to handle requests for L2s yet */ - tlb_flush_fifo = &hv_vcpu->tlb_flush_fifo[HV_L1_TLB_FLUSH_FIFO]; - spin_lock(&tlb_flush_fifo->write_lock); /* @@ -1912,6 +1911,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) struct hv_tlb_flush_ex flush_ex; struct hv_tlb_flush flush; DECLARE_BITMAP(vcpu_mask, KVM_MAX_VCPUS); + struct kvm_vcpu_hv_tlb_flush_fifo *tlb_flush_fifo; /* * Normally, there can be no more than 'KVM_HV_TLB_FLUSH_FIFO_SIZE' * entries on the TLB flush fifo. The last entry, however, needs to be @@ -1962,7 +1962,8 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) } trace_kvm_hv_flush_tlb(flush.processor_mask, - flush.address_space, flush.flags); + flush.address_space, flush.flags, + is_guest_mode(vcpu)); valid_bank_mask = BIT_ULL(0); sparse_banks[0] = flush.processor_mask; @@ -1993,7 +1994,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) trace_kvm_hv_flush_tlb_ex(flush_ex.hv_vp_set.valid_bank_mask, flush_ex.hv_vp_set.format, flush_ex.address_space, - flush_ex.flags); + flush_ex.flags, is_guest_mode(vcpu)); valid_bank_mask = flush_ex.hv_vp_set.valid_bank_mask; all_cpus = flush_ex.hv_vp_set.format != @@ -2037,19 +2038,57 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) * 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. */ - if (all_cpus) { - kvm_for_each_vcpu(i, v, kvm) - hv_tlb_flush_enqueue(v, tlb_flush_entries, hc->rep_cnt); + if (all_cpus && !is_guest_mode(vcpu)) { + kvm_for_each_vcpu(i, v, kvm) { + tlb_flush_fifo = kvm_hv_get_tlb_flush_fifo(v, false); + hv_tlb_flush_enqueue(v, tlb_flush_fifo, + tlb_flush_entries, hc->rep_cnt); + } kvm_make_all_cpus_request(kvm, KVM_REQ_HV_TLB_FLUSH); - } else { + } else if (!is_guest_mode(vcpu)) { sparse_set_to_vcpu_mask(kvm, sparse_banks, valid_bank_mask, vcpu_mask); for_each_set_bit(i, vcpu_mask, KVM_MAX_VCPUS) { v = kvm_get_vcpu(kvm, i); if (!v) continue; - hv_tlb_flush_enqueue(v, tlb_flush_entries, hc->rep_cnt); + tlb_flush_fifo = kvm_hv_get_tlb_flush_fifo(v, false); + hv_tlb_flush_enqueue(v, tlb_flush_fifo, + tlb_flush_entries, hc->rep_cnt); + } + + kvm_make_vcpus_request_mask(kvm, KVM_REQ_HV_TLB_FLUSH, vcpu_mask); + } else { + struct kvm_vcpu_hv *hv_v; + + bitmap_zero(vcpu_mask, KVM_MAX_VCPUS); + + kvm_for_each_vcpu(i, v, kvm) { + hv_v = to_hv_vcpu(v); + + /* + * The following check races with nested vCPUs entering/exiting + * and/or migrating between L1's vCPUs, however the only case when + * KVM *must* flush the TLB is when the target L2 vCPU keeps + * running on the same L1 vCPU from the moment of the request until + * kvm_hv_flush_tlb() returns. TLB is fully flushed in all other + * cases, e.g. when the target L2 vCPU migrates to a different L1 + * vCPU or when the corresponding L1 vCPU temporary switches to a + * different L2 vCPU while the request is being processed. + */ + if (!hv_v || hv_v->nested.vm_id != hv_vcpu->nested.vm_id) + continue; + + if (!all_cpus && + !hv_is_vp_in_sparse_set(hv_v->nested.vp_id, valid_bank_mask, + sparse_banks)) + continue; + + __set_bit(i, vcpu_mask); + tlb_flush_fifo = kvm_hv_get_tlb_flush_fifo(v, true); + hv_tlb_flush_enqueue(v, tlb_flush_fifo, + tlb_flush_entries, hc->rep_cnt); } kvm_make_vcpus_request_mask(kvm, KVM_REQ_HV_TLB_FLUSH, vcpu_mask); @@ -2239,10 +2278,25 @@ static void kvm_hv_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result) static int kvm_hv_hypercall_complete(struct kvm_vcpu *vcpu, u64 result) { + u32 tlb_lock_count = 0; + int ret; + + if (hv_result_success(result) && is_guest_mode(vcpu) && + kvm_hv_is_tlb_flush_hcall(vcpu) && + kvm_read_guest(vcpu->kvm, to_hv_vcpu(vcpu)->nested.pa_page_gpa, + &tlb_lock_count, sizeof(tlb_lock_count))) + result = HV_STATUS_INVALID_HYPERCALL_INPUT; + trace_kvm_hv_hypercall_done(result); kvm_hv_hypercall_set_result(vcpu, result); ++vcpu->stat.hypercalls; - return kvm_skip_emulated_instruction(vcpu); + + ret = kvm_skip_emulated_instruction(vcpu); + + if (tlb_lock_count) + kvm_x86_ops.nested_ops->hv_inject_synthetic_vmexit_post_tlb_flush(vcpu); + + return ret; } static int kvm_hv_hypercall_complete_userspace(struct kvm_vcpu *vcpu) diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h index 5f9c76b..7706e20 100644 --- a/arch/x86/kvm/hyperv.h +++ b/arch/x86/kvm/hyperv.h @@ -159,9 +159,6 @@ static inline struct kvm_vcpu_hv_tlb_flush_fifo *kvm_hv_get_tlb_flush_fifo(struc int i = is_guest_mode ? HV_L2_TLB_FLUSH_FIFO : HV_L1_TLB_FLUSH_FIFO; - /* KVM does not handle L2 TLB flush requests yet */ - WARN_ON_ONCE(i != HV_L1_TLB_FLUSH_FIFO); - return &hv_vcpu->tlb_flush_fifo[i]; } diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h index bc25589..09f3392 100644 --- a/arch/x86/kvm/trace.h +++ b/arch/x86/kvm/trace.h @@ -1547,38 +1547,41 @@ TRACE_EVENT(kvm_hv_timer_state, * 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_PROTO(u64 processor_mask, u64 address_space, u64 flags, bool guest_mode), + TP_ARGS(processor_mask, address_space, flags, guest_mode), TP_STRUCT__entry( __field(u64, processor_mask) __field(u64, address_space) __field(u64, flags) + __field(bool, guest_mode) ), TP_fast_assign( __entry->processor_mask = processor_mask; __entry->address_space = address_space; __entry->flags = flags; + __entry->guest_mode = guest_mode; ), - TP_printk("processor_mask 0x%llx address_space 0x%llx flags 0x%llx", + TP_printk("processor_mask 0x%llx address_space 0x%llx flags 0x%llx %s", __entry->processor_mask, __entry->address_space, - __entry->flags) + __entry->flags, __entry->guest_mode ? "(L2)" : "") ); /* * Tracepoint for kvm_hv_flush_tlb_ex. */ TRACE_EVENT(kvm_hv_flush_tlb_ex, - TP_PROTO(u64 valid_bank_mask, u64 format, u64 address_space, u64 flags), - TP_ARGS(valid_bank_mask, format, address_space, flags), + TP_PROTO(u64 valid_bank_mask, u64 format, u64 address_space, u64 flags, bool guest_mode), + TP_ARGS(valid_bank_mask, format, address_space, flags, guest_mode), TP_STRUCT__entry( __field(u64, valid_bank_mask) __field(u64, format) __field(u64, address_space) __field(u64, flags) + __field(bool, guest_mode) ), TP_fast_assign( @@ -1586,12 +1589,14 @@ TRACE_EVENT(kvm_hv_flush_tlb_ex, __entry->format = format; __entry->address_space = address_space; __entry->flags = flags; + __entry->guest_mode = guest_mode; ), TP_printk("valid_bank_mask 0x%llx format 0x%llx " - "address_space 0x%llx flags 0x%llx", + "address_space 0x%llx flags 0x%llx %s", __entry->valid_bank_mask, __entry->format, - __entry->address_space, __entry->flags) + __entry->address_space, __entry->flags, + __entry->guest_mode ? "(L2)" : "") ); /* -- 2.7.4