diff options
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 6 | ||||
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 1 | ||||
| -rw-r--r-- | arch/x86/kvm/lapic.c | 53 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 5 | ||||
| -rw-r--r-- | include/uapi/linux/kvm.h | 1 |
5 files changed, 52 insertions, 14 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index e34e51fa28b0..c4d2fb0e28de 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -3844,12 +3844,18 @@ Returns: 0 on success, -EINVAL when args[0] contains invalid features Valid feature flags in args[0] are #define KVM_X2APIC_API_USE_32BIT_IDS (1ULL << 0) +#define KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK (1ULL << 1) Enabling KVM_X2APIC_API_USE_32BIT_IDS changes the behavior of KVM_SET_GSI_ROUTING, KVM_SIGNAL_MSI, KVM_SET_LAPIC, and KVM_GET_LAPIC, allowing the use of 32-bit APIC IDs. See KVM_CAP_X2APIC_API in their respective sections. +KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK must be enabled for x2APIC to work +in logical mode or with more than 255 VCPUs. Otherwise, KVM treats 0xff +as a broadcast even in x2APIC mode in order to support physical x2APIC +without interrupt remapping. This is undesirable in logical mode, +where 0xff represents CPUs 0-7 in cluster 0. 8. Other capabilities. diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 7c00ba3242d7..074b5c760327 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -784,6 +784,7 @@ struct kvm_arch { struct page *avic_physical_id_table_page; bool x2apic_format; + bool x2apic_broadcast_quirk_disabled; }; struct kvm_vm_stat { diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index d27a7829a4ce..a16e0bb95d28 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -616,17 +616,30 @@ static bool kvm_apic_match_logical_addr(struct kvm_lapic *apic, u32 mda) } } -/* KVM APIC implementation has two quirks - * - dest always begins at 0 while xAPIC MDA has offset 24, - * - IOxAPIC messages have to be delivered (directly) to x2APIC. +/* The KVM local APIC implementation has two quirks: + * + * - the xAPIC MDA stores the destination at bits 24-31, while this + * is not true of struct kvm_lapic_irq's dest_id field. This is + * just a quirk in the API and is not problematic. + * + * - in-kernel IOAPIC messages have to be delivered directly to + * x2APIC, because the kernel does not support interrupt remapping. + * In order to support broadcast without interrupt remapping, x2APIC + * rewrites the destination of non-IPI messages from APIC_BROADCAST + * to X2APIC_BROADCAST. + * + * The broadcast quirk can be disabled with KVM_CAP_X2APIC_API. This is + * important when userspace wants to use x2APIC-format MSIs, because + * APIC_BROADCAST (0xff) is a legal route for "cluster 0, CPUs 0-7". */ -static u32 kvm_apic_mda(unsigned int dest_id, struct kvm_lapic *source, - struct kvm_lapic *target) +static u32 kvm_apic_mda(struct kvm_vcpu *vcpu, unsigned int dest_id, + struct kvm_lapic *source, struct kvm_lapic *target) { bool ipi = source != NULL; bool x2apic_mda = apic_x2apic_mode(ipi ? source : target); - if (!ipi && dest_id == APIC_BROADCAST && x2apic_mda) + if (!vcpu->kvm->arch.x2apic_broadcast_quirk_disabled && + !ipi && dest_id == APIC_BROADCAST && x2apic_mda) return X2APIC_BROADCAST; return x2apic_mda ? dest_id : SET_APIC_DEST_FIELD(dest_id); @@ -636,7 +649,7 @@ bool kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source, int short_hand, unsigned int dest, int dest_mode) { struct kvm_lapic *target = vcpu->arch.apic; - u32 mda = kvm_apic_mda(dest, source, target); + u32 mda = kvm_apic_mda(vcpu, dest, source, target); apic_debug("target %p, source %p, dest 0x%x, " "dest_mode 0x%x, short_hand 0x%x\n", @@ -688,6 +701,25 @@ static void kvm_apic_disabled_lapic_found(struct kvm *kvm) } } +static bool kvm_apic_is_broadcast_dest(struct kvm *kvm, struct kvm_lapic **src, + struct kvm_lapic_irq *irq, struct kvm_apic_map *map) +{ + if (kvm->arch.x2apic_broadcast_quirk_disabled) { + if ((irq->dest_id == APIC_BROADCAST && + map->mode != KVM_APIC_MODE_X2APIC)) + return true; + if (irq->dest_id == X2APIC_BROADCAST) + return true; + } else { + bool x2apic_ipi = src && *src && apic_x2apic_mode(*src); + if (irq->dest_id == (x2apic_ipi ? + X2APIC_BROADCAST : APIC_BROADCAST)) + return true; + } + + return false; +} + /* Return true if the interrupt can be handled by using *bitmap as index mask * for valid destinations in *dst array. * Return false if kvm_apic_map_get_dest_lapic did nothing useful. @@ -701,7 +733,6 @@ static inline bool kvm_apic_map_get_dest_lapic(struct kvm *kvm, unsigned long *bitmap) { int i, lowest; - bool x2apic_ipi; if (irq->shorthand == APIC_DEST_SELF && src) { *dst = src; @@ -710,11 +741,7 @@ static inline bool kvm_apic_map_get_dest_lapic(struct kvm *kvm, } else if (irq->shorthand) return false; - x2apic_ipi = src && *src && apic_x2apic_mode(*src); - if (irq->dest_id == (x2apic_ipi ? X2APIC_BROADCAST : APIC_BROADCAST)) - return false; - - if (!map) + if (!map || kvm_apic_is_broadcast_dest(kvm, src, irq, map)) return false; if (irq->dest_mode == APIC_DEST_PHYSICAL) { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d86f563a6896..f0d23622bc4e 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -90,7 +90,8 @@ static u64 __read_mostly efer_reserved_bits = ~((u64)EFER_SCE); #define VM_STAT(x) offsetof(struct kvm, stat.x), KVM_STAT_VM #define VCPU_STAT(x) offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU -#define KVM_X2APIC_API_VALID_FLAGS (KVM_X2APIC_API_USE_32BIT_IDS) +#define KVM_X2APIC_API_VALID_FLAGS (KVM_X2APIC_API_USE_32BIT_IDS | \ + KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK) static void update_cr8_intercept(struct kvm_vcpu *vcpu); static void process_nmi(struct kvm_vcpu *vcpu); @@ -3811,6 +3812,8 @@ split_irqchip_unlock: if (cap->args[0] & KVM_X2APIC_API_USE_32BIT_IDS) kvm->arch.x2apic_format = true; + if (cap->args[0] & KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK) + kvm->arch.x2apic_broadcast_quirk_disabled = true; r = 0; break; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index f704403e19a0..4f8030e5b05d 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1315,5 +1315,6 @@ struct kvm_assigned_msix_entry { }; #define KVM_X2APIC_API_USE_32BIT_IDS (1ULL << 0) +#define KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK (1ULL << 1) #endif /* __LINUX_KVM_H */ |