From bbfc7aa62a4a9baff264f1fd91175b6249843984 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 6 Jan 2023 01:13:01 +0000 Subject: [PATCH] KVM: SVM: Handle multiple logical targets in AVIC kick fastpath Iterate over all target logical IDs in the AVIC kick fastpath instead of bailing if there is more than one target. Now that KVM inhibits AVIC if vCPUs aren't mapped 1:1 with logical IDs, each bit in the destination is guaranteed to match to at most one vCPU, i.e. iterating over the bitmap is guaranteed to kick each valid target exactly once. Reviewed-by: Maxim Levitsky Signed-off-by: Sean Christopherson Message-Id: <20230106011306.85230-29-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/avic.c | 110 +++++++++++++++++++++++++++--------------------- 1 file changed, 62 insertions(+), 48 deletions(-) diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index eb97969..2c6737f 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -327,6 +327,50 @@ static void avic_kick_vcpu(struct kvm_vcpu *vcpu, u32 icrl) icrl & APIC_VECTOR_MASK); } +static void avic_kick_vcpu_by_physical_id(struct kvm *kvm, u32 physical_id, + u32 icrl) +{ + /* + * KVM inhibits AVIC if any vCPU ID diverges from the vCPUs APIC ID, + * i.e. APIC ID == vCPU ID. + */ + struct kvm_vcpu *target_vcpu = kvm_get_vcpu_by_id(kvm, physical_id); + + /* Once again, nothing to do if the target vCPU doesn't exist. */ + if (unlikely(!target_vcpu)) + return; + + avic_kick_vcpu(target_vcpu, icrl); +} + +static void avic_kick_vcpu_by_logical_id(struct kvm *kvm, u32 *avic_logical_id_table, + u32 logid_index, u32 icrl) +{ + u32 physical_id; + + if (avic_logical_id_table) { + u32 logid_entry = avic_logical_id_table[logid_index]; + + /* Nothing to do if the logical destination is invalid. */ + if (unlikely(!(logid_entry & AVIC_LOGICAL_ID_ENTRY_VALID_MASK))) + return; + + physical_id = logid_entry & + AVIC_LOGICAL_ID_ENTRY_GUEST_PHYSICAL_ID_MASK; + } else { + /* + * For x2APIC, the logical APIC ID is a read-only value that is + * derived from the x2APIC ID, thus the x2APIC ID can be found + * by reversing the calculation (stored in logid_index). Note, + * bits 31:20 of the x2APIC ID aren't propagated to the logical + * ID, but KVM limits the x2APIC ID limited to KVM_MAX_VCPU_IDS. + */ + physical_id = logid_index; + } + + avic_kick_vcpu_by_physical_id(kvm, physical_id, icrl); +} + /* * A fast-path version of avic_kick_target_vcpus(), which attempts to match * destination APIC ID to vCPU without looping through all vCPUs. @@ -334,11 +378,10 @@ static void avic_kick_vcpu(struct kvm_vcpu *vcpu, u32 icrl) static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source, u32 icrl, u32 icrh, u32 index) { - u32 l1_physical_id, dest; - struct kvm_vcpu *target_vcpu; int dest_mode = icrl & APIC_DEST_MASK; int shorthand = icrl & APIC_SHORT_MASK; struct kvm_svm *kvm_svm = to_kvm_svm(kvm); + u32 dest; if (shorthand != APIC_DEST_NOSHORT) return -EINVAL; @@ -355,14 +398,14 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source if (!apic_x2apic_mode(source) && dest == APIC_BROADCAST) return -EINVAL; - l1_physical_id = dest; - - if (WARN_ON_ONCE(l1_physical_id != index)) + if (WARN_ON_ONCE(dest != index)) return -EINVAL; + avic_kick_vcpu_by_physical_id(kvm, dest, icrl); } else { - u32 bitmap, cluster; - int logid_index; + u32 *avic_logical_id_table; + unsigned long bitmap, i; + u32 cluster; if (apic_x2apic_mode(source)) { /* 16 bit dest mask, 16 bit cluster id */ @@ -382,50 +425,21 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source if (unlikely(!bitmap)) return 0; - if (!is_power_of_2(bitmap)) - /* multiple logical destinations, use slow path */ - return -EINVAL; - - logid_index = cluster + __ffs(bitmap); - - if (apic_x2apic_mode(source)) { - /* - * For x2APIC, the logical APIC ID is a read-only value - * that is derived from the x2APIC ID, thus the x2APIC - * ID can be found by reversing the calculation (done - * above). Note, bits 31:20 of the x2APIC ID are not - * propagated to the logical ID, but KVM limits the - * x2APIC ID limited to KVM_MAX_VCPU_IDS. - */ - l1_physical_id = logid_index; - } else { - u32 *avic_logical_id_table = - page_address(kvm_svm->avic_logical_id_table_page); - - u32 logid_entry = avic_logical_id_table[logid_index]; - - if (WARN_ON_ONCE(index != logid_index)) - return -EINVAL; - - /* Nothing to do if the logical destination is invalid. */ - if (unlikely(!(logid_entry & AVIC_LOGICAL_ID_ENTRY_VALID_MASK))) - return 0; + if (apic_x2apic_mode(source)) + avic_logical_id_table = NULL; + else + avic_logical_id_table = page_address(kvm_svm->avic_logical_id_table_page); - l1_physical_id = logid_entry & - AVIC_LOGICAL_ID_ENTRY_GUEST_PHYSICAL_ID_MASK; - } + /* + * AVIC is inhibited if vCPUs aren't mapped 1:1 with logical + * IDs, thus each bit in the destination is guaranteed to map + * to at most one vCPU. + */ + for_each_set_bit(i, &bitmap, 16) + avic_kick_vcpu_by_logical_id(kvm, avic_logical_id_table, + cluster + i, icrl); } - /* - * KVM inhibits AVIC if any vCPU ID diverges from the vCPUs APIC ID, - * i.e. APIC ID == vCPU ID. Once again, nothing to do if the target - * vCPU doesn't exist. - */ - target_vcpu = kvm_get_vcpu_by_id(kvm, l1_physical_id); - if (unlikely(!target_vcpu)) - return 0; - - avic_kick_vcpu(target_vcpu, icrl); return 0; } -- 2.7.4