The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4a204f7895878363ca8211f50ec610408c8c70aa Mon Sep 17 00:00:00 2001 From: Suravee Suthikulpanit suravee.suthikulpanit@amd.com Date: Thu, 10 Feb 2022 18:08:51 -0600 Subject: [PATCH] KVM: SVM: Allow AVIC support on system w/ physical APIC ID > 255

Expand KVM's mask for the AVIC host physical ID to the full 12 bits defined by the architecture. The number of bits consumed by hardware is model specific, e.g. early CPUs ignored bits 11:8, but there is no way for KVM to enumerate the "true" size. So, KVM must allow using all bits, else it risks rejecting completely legal x2APIC IDs on newer CPUs.

This means KVM relies on hardware to not assign x2APIC IDs that exceed the "true" width of the field, but presumably hardware is smart enough to tie the width to the max x2APIC ID. KVM also relies on hardware to support at least 8 bits, as the legacy xAPIC ID is writable by software. But, those assumptions are unavoidable due to the lack of any way to enumerate the "true" width.

Cc: stable@vger.kernel.org Cc: Maxim Levitsky mlevitsk@redhat.com Suggested-by: Sean Christopherson seanjc@google.com Reviewed-by: Sean Christopherson seanjc@google.com Fixes: 44a95dae1d22 ("KVM: x86: Detect and Initialize AVIC support") Signed-off-by: Suravee Suthikulpanit suravee.suthikulpanit@amd.com Message-Id: 20220211000851.185799-1-suravee.suthikulpanit@amd.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h index bb2fb78523ce..7eb2df5417fb 100644 --- a/arch/x86/include/asm/svm.h +++ b/arch/x86/include/asm/svm.h @@ -226,7 +226,7 @@ struct __attribute__ ((__packed__)) vmcb_control_area { #define AVIC_LOGICAL_ID_ENTRY_VALID_BIT 31 #define AVIC_LOGICAL_ID_ENTRY_VALID_MASK (1 << 31)

-#define AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK (0xFFULL) +#define AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK GENMASK_ULL(11, 0) #define AVIC_PHYSICAL_ID_ENTRY_BACKING_PAGE_MASK (0xFFFFFFFFFFULL << 12) #define AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK (1ULL << 62) #define AVIC_PHYSICAL_ID_ENTRY_VALID_MASK (1ULL << 63) diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index 1afde44b1252..b37b353ec086 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -870,17 +870,12 @@ avic_update_iommu_vcpu_affinity(struct kvm_vcpu *vcpu, int cpu, bool r) void __avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu) { u64 entry; - /* ID = 0xff (broadcast), ID > 0xff (reserved) */ int h_physical_id = kvm_cpu_get_apicid(cpu); struct vcpu_svm *svm = to_svm(vcpu);

lockdep_assert_preemption_disabled();

- /* - * Since the host physical APIC id is 8 bits, - * we can support host APIC ID upto 255. - */ - if (WARN_ON(h_physical_id > AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK)) + if (WARN_ON(h_physical_id & ~AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK)) return;

/* diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index e45b5645d5e0..e37bb3508cfa 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -569,6 +569,17 @@ extern struct kvm_x86_nested_ops svm_nested_ops;

/* avic.c */

+#define AVIC_LOGICAL_ID_ENTRY_GUEST_PHYSICAL_ID_MASK (0xFF) +#define AVIC_LOGICAL_ID_ENTRY_VALID_BIT 31 +#define AVIC_LOGICAL_ID_ENTRY_VALID_MASK (1 << 31) + +#define AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK GENMASK_ULL(11, 0) +#define AVIC_PHYSICAL_ID_ENTRY_BACKING_PAGE_MASK (0xFFFFFFFFFFULL << 12) +#define AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK (1ULL << 62) +#define AVIC_PHYSICAL_ID_ENTRY_VALID_MASK (1ULL << 63) + +#define VMCB_AVIC_APIC_BAR_MASK 0xFFFFFFFFFF000ULL + int avic_ga_log_notifier(u32 ga_tag); void avic_vm_destroy(struct kvm *kvm); int avic_vm_init(struct kvm *kvm);