KVM: x86: Detect and Initialize AVIC support

This patch introduces AVIC-related data structure, and AVIC
initialization code.

There are three main data structures for AVIC:
    * Virtual APIC (vAPIC) backing page (per-VCPU)
    * Physical APIC ID table (per-VM)
    * Logical APIC ID table (per-VM)

Currently, AVIC is disabled by default. Users can manually
enable AVIC via kernel boot option kvm-amd.avic=1 or during
kvm-amd module loading with parameter avic=1.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
[Avoid extra indentation (Boris). - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 231 insertions, 1 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2df5db6fb58b..337e13b0d01d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -773,6 +773,10 @@ struct kvm_arch {
         u8 nr_reserved_ioapic_pins;
 
         bool disabled_lapic_found;
+
+        /* Struct members for AVIC */
+        struct page *avic_logical_id_table_page;
+        struct page *avic_physical_id_table_page;
 };
 
 struct kvm_vm_stat {
diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 4711fa4457f3..d0fe23ec7e98 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -116,6 +116,9 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 #define V_INTR_MASKING_SHIFT 24
 #define V_INTR_MASKING_MASK (1 << V_INTR_MASKING_SHIFT)
 
+#define AVIC_ENABLE_SHIFT 31
+#define AVIC_ENABLE_MASK (1 << AVIC_ENABLE_SHIFT)
+
 #define SVM_INTERRUPT_SHADOW_MASK 1
 
 #define SVM_IOIO_STR_SHIFT 2
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 31346a3f20a5..192cad25d321 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -14,6 +14,9 @@
  * the COPYING file in the top-level directory.
  *
  */
+
+#define pr_fmt(fmt) "SVM: " fmt
+
 #include <linux/kvm_host.h>
 
 #include "irq.h"
@@ -78,6 +81,14 @@ MODULE_DEVICE_TABLE(x86cpu, svm_cpu_id);
 #define TSC_RATIO_MIN           0x0000000000000001ULL
 #define TSC_RATIO_MAX           0x000000ffffffffffULL
 
+#define AVIC_HPA_MASK   ~((0xFFFULL << 52) || 0xFFF)
+
+/*
+ * 0xff is broadcast, so the max index allowed for physical APIC ID
+ * table is 0xfe.  APIC IDs above 0xff are reserved.
+ */
+#define AVIC_MAX_PHYSICAL_ID_COUNT      255
+
 static bool erratum_383_found __read_mostly;
 
 static const u32 host_save_user_msrs[] = {
@@ -162,8 +173,19 @@ struct vcpu_svm {
 
         /* cached guest cpuid flags for faster access */
         bool nrips_enabled      : 1;
+
+        struct page *avic_backing_page;
+        u64 *avic_physical_id_cache;
 };
 
+#define AVIC_LOGICAL_ID_ENTRY_GUEST_PHYSICAL_ID_MASK    (0xFF)
+#define AVIC_LOGICAL_ID_ENTRY_VALID_MASK                (1 << 31)
+
+#define AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK    (0xFFULL)
+#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)
+
 static DEFINE_PER_CPU(u64, current_tsc_ratio);
 #define TSC_RATIO_DEFAULT       0x0100000000ULL
 
@@ -205,6 +227,10 @@ module_param(npt, int, S_IRUGO);
 static int nested = true;
 module_param(nested, int, S_IRUGO);
 
+/* enable / disable AVIC */
+static int avic;
+module_param(avic, int, S_IRUGO);
+
 static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
 static void svm_flush_tlb(struct kvm_vcpu *vcpu);
 static void svm_complete_interrupts(struct vcpu_svm *svm);
@@ -228,12 +254,18 @@ enum {
         VMCB_SEG,        /* CS, DS, SS, ES, CPL */
         VMCB_CR2,        /* CR2 only */
         VMCB_LBR,        /* DBGCTL, BR_FROM, BR_TO, LAST_EX_FROM, LAST_EX_TO */
+        VMCB_AVIC,       /* AVIC APIC_BAR, AVIC APIC_BACKING_PAGE,
+                          * AVIC PHYSICAL_TABLE pointer,
+                          * AVIC LOGICAL_TABLE pointer
+                          */
         VMCB_DIRTY_MAX,
 };
 
 /* TPR and CR2 are always written before VMRUN */
 #define VMCB_ALWAYS_DIRTY_MASK  ((1U << VMCB_INTR) | (1U << VMCB_CR2))
 
+#define VMCB_AVIC_APIC_BAR_MASK         0xFFFFFFFFFF000ULL
+
 static inline void mark_all_dirty(struct vmcb *vmcb)
 {
         vmcb->control.clean = 0;
@@ -255,6 +287,12 @@ static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
         return container_of(vcpu, struct vcpu_svm, vcpu);
 }
 
+static inline void avic_update_vapic_bar(struct vcpu_svm *svm, u64 data)
+{
+        svm->vmcb->control.avic_vapic_bar = data & VMCB_AVIC_APIC_BAR_MASK;
+        mark_dirty(svm->vmcb, VMCB_AVIC);
+}
+
 static void recalc_intercepts(struct vcpu_svm *svm)
 {
         struct vmcb_control_area *c, *h;
@@ -923,6 +961,12 @@ static __init int svm_hardware_setup(void)
         } else
                 kvm_disable_tdp();
 
+        if (avic && (!npt_enabled || !boot_cpu_has(X86_FEATURE_AVIC)))
+                avic = false;
+
+        if (avic)
+                pr_info("AVIC enabled\n");
+
         return 0;
 
 err:
@@ -1000,6 +1044,22 @@ static void svm_adjust_tsc_offset_guest(struct kvm_vcpu *vcpu, s64 adjustment)
         mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
 }
 
+static void avic_init_vmcb(struct vcpu_svm *svm)
+{
+        struct vmcb *vmcb = svm->vmcb;
+        struct kvm_arch *vm_data = &svm->vcpu.kvm->arch;
+        phys_addr_t bpa = page_to_phys(svm->avic_backing_page);
+        phys_addr_t lpa = page_to_phys(vm_data->avic_logical_id_table_page);
+        phys_addr_t ppa = page_to_phys(vm_data->avic_physical_id_table_page);
+
+        vmcb->control.avic_backing_page = bpa & AVIC_HPA_MASK;
+        vmcb->control.avic_logical_id = lpa & AVIC_HPA_MASK;
+        vmcb->control.avic_physical_id = ppa & AVIC_HPA_MASK;
+        vmcb->control.avic_physical_id |= AVIC_MAX_PHYSICAL_ID_COUNT;
+        vmcb->control.int_ctl |= AVIC_ENABLE_MASK;
+        svm->vcpu.arch.apicv_active = true;
+}
+
 static void init_vmcb(struct vcpu_svm *svm)
 {
         struct vmcb_control_area *control = &svm->vmcb->control;
@@ -1110,9 +1170,131 @@ static void init_vmcb(struct vcpu_svm *svm)
                 set_intercept(svm, INTERCEPT_PAUSE);
         }
 
+        if (avic)
+                avic_init_vmcb(svm);
+
         mark_all_dirty(svm->vmcb);
 
         enable_gif(svm);
+
+}
+
+static u64 *avic_get_physical_id_entry(struct kvm_vcpu *vcpu, int index)
+{
+        u64 *avic_physical_id_table;
+        struct kvm_arch *vm_data = &vcpu->kvm->arch;
+
+        if (index >= AVIC_MAX_PHYSICAL_ID_COUNT)
+                return NULL;
+
+        avic_physical_id_table = page_address(vm_data->avic_physical_id_table_page);
+
+        return &avic_physical_id_table[index];
+}
+
+/**
+ * Note:
+ * AVIC hardware walks the nested page table to check permissions,
+ * but does not use the SPA address specified in the leaf page
+ * table entry since it uses  address in the AVIC_BACKING_PAGE pointer
+ * field of the VMCB. Therefore, we set up the
+ * APIC_ACCESS_PAGE_PRIVATE_MEMSLOT (4KB) here.
+ */
+static int avic_init_access_page(struct kvm_vcpu *vcpu)
+{
+        struct kvm *kvm = vcpu->kvm;
+        int ret;
+
+        if (kvm->arch.apic_access_page_done)
+                return 0;
+
+        ret = x86_set_memory_region(kvm,
+                                    APIC_ACCESS_PAGE_PRIVATE_MEMSLOT,
+                                    APIC_DEFAULT_PHYS_BASE,
+                                    PAGE_SIZE);
+        if (ret)
+                return ret;
+
+        kvm->arch.apic_access_page_done = true;
+        return 0;
+}
+
+static int avic_init_backing_page(struct kvm_vcpu *vcpu)
+{
+        int ret;
+        u64 *entry, new_entry;
+        int id = vcpu->vcpu_id;
+        struct vcpu_svm *svm = to_svm(vcpu);
+
+        ret = avic_init_access_page(vcpu);
+        if (ret)
+                return ret;
+
+        if (id >= AVIC_MAX_PHYSICAL_ID_COUNT)
+                return -EINVAL;
+
+        if (!svm->vcpu.arch.apic->regs)
+                return -EINVAL;
+
+        svm->avic_backing_page = virt_to_page(svm->vcpu.arch.apic->regs);
+
+        /* Setting AVIC backing page address in the phy APIC ID table */
+        entry = avic_get_physical_id_entry(vcpu, id);
+        if (!entry)
+                return -EINVAL;
+
+        new_entry = READ_ONCE(*entry);
+        new_entry = (page_to_phys(svm->avic_backing_page) &
+                     AVIC_PHYSICAL_ID_ENTRY_BACKING_PAGE_MASK) |
+                     AVIC_PHYSICAL_ID_ENTRY_VALID_MASK;
+        WRITE_ONCE(*entry, new_entry);
+
+        svm->avic_physical_id_cache = entry;
+
+        return 0;
+}
+
+static void avic_vm_destroy(struct kvm *kvm)
+{
+        struct kvm_arch *vm_data = &kvm->arch;
+
+        if (vm_data->avic_logical_id_table_page)
+                __free_page(vm_data->avic_logical_id_table_page);
+        if (vm_data->avic_physical_id_table_page)
+                __free_page(vm_data->avic_physical_id_table_page);
+}
+
+static int avic_vm_init(struct kvm *kvm)
+{
+        int err = -ENOMEM;
+        struct kvm_arch *vm_data = &kvm->arch;
+        struct page *p_page;
+        struct page *l_page;
+
+        if (!avic)
+                return 0;
+
+        /* Allocating physical APIC ID table (4KB) */
+        p_page = alloc_page(GFP_KERNEL);
+        if (!p_page)
+                goto free_avic;
+
+        vm_data->avic_physical_id_table_page = p_page;
+        clear_page(page_address(p_page));
+
+        /* Allocating logical APIC ID table (4KB) */
+        l_page = alloc_page(GFP_KERNEL);
+        if (!l_page)
+                goto free_avic;
+
+        vm_data->avic_logical_id_table_page = l_page;
+        clear_page(page_address(l_page));
+
+        return 0;
+
+free_avic:
+        avic_vm_destroy(kvm);
+        return err;
 }
 
 static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
@@ -1131,6 +1313,9 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 
         kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy);
         kvm_register_write(vcpu, VCPU_REGS_RDX, eax);
+
+        if (kvm_vcpu_apicv_active(vcpu) && !init_event)
+                avic_update_vapic_bar(svm, APIC_DEFAULT_PHYS_BASE);
 }
 
 static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
@@ -1169,6 +1354,12 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
         if (!hsave_page)
                 goto free_page3;
 
+        if (avic) {
+                err = avic_init_backing_page(&svm->vcpu);
+                if (err)
+                        goto free_page4;
+        }
+
         svm->nested.hsave = page_address(hsave_page);
 
         svm->msrpm = page_address(msrpm_pages);
@@ -1187,6 +1378,8 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
 
         return &svm->vcpu;
 
+free_page4:
+        __free_page(hsave_page);
 free_page3:
         __free_pages(nested_msrpm_pages, MSRPM_ALLOC_ORDER);
 free_page2:
@@ -3212,6 +3405,10 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
         case MSR_VM_IGNNE:
                 vcpu_unimpl(vcpu, "unimplemented wrmsr: 0x%x data 0x%llx\n", ecx, data);
                 break;
+        case MSR_IA32_APICBASE:
+                if (kvm_vcpu_apicv_active(vcpu))
+                        avic_update_vapic_bar(to_svm(vcpu), data);
+                /* Follow through */
         default:
                 return kvm_set_msr_common(vcpu, msr);
         }
@@ -3375,10 +3572,14 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
         pr_err("%-20s%08x\n", "exit_int_info_err:", control->exit_int_info_err);
         pr_err("%-20s%lld\n", "nested_ctl:", control->nested_ctl);
         pr_err("%-20s%016llx\n", "nested_cr3:", control->nested_cr3);
+        pr_err("%-20s%016llx\n", "avic_vapic_bar:", control->avic_vapic_bar);
         pr_err("%-20s%08x\n", "event_inj:", control->event_inj);
         pr_err("%-20s%08x\n", "event_inj_err:", control->event_inj_err);
         pr_err("%-20s%lld\n", "lbr_ctl:", control->lbr_ctl);
         pr_err("%-20s%016llx\n", "next_rip:", control->next_rip);
+        pr_err("%-20s%016llx\n", "avic_backing_page:", control->avic_backing_page);
+        pr_err("%-20s%016llx\n", "avic_logical_id:", control->avic_logical_id);
+        pr_err("%-20s%016llx\n", "avic_physical_id:", control->avic_physical_id);
         pr_err("VMCB State Save Area:\n");
         pr_err("%-5s s: %04x a: %04x l: %08x b: %016llx\n",
                "es:",
@@ -3606,11 +3807,28 @@ static void svm_set_virtual_x2apic_mode(struct kvm_vcpu *vcpu, bool set)
 
 static bool svm_get_enable_apicv(void)
 {
-        return false;
+        return avic;
+}
+
+static void svm_hwapic_irr_update(struct kvm_vcpu *vcpu, int max_irr)
+{
+}
+
+static void svm_hwapic_isr_update(struct kvm *kvm, int isr)
+{
 }
 
+/* Note: Currently only used by Hyper-V. */
 static void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
 {
+        struct vcpu_svm *svm = to_svm(vcpu);
+        struct vmcb *vmcb = svm->vmcb;
+
+        if (!avic)
+                return;
+
+        vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
+        mark_dirty(vmcb, VMCB_INTR);
 }
 
 static void svm_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
@@ -4322,6 +4540,9 @@ static struct kvm_x86_ops svm_x86_ops = {
         .vcpu_free = svm_free_vcpu,
         .vcpu_reset = svm_vcpu_reset,
 
+        .vm_init = avic_vm_init,
+        .vm_destroy = avic_vm_destroy,
+
         .prepare_guest_switch = svm_prepare_guest_switch,
         .vcpu_load = svm_vcpu_load,
         .vcpu_put = svm_vcpu_put,
@@ -4382,6 +4603,8 @@ static struct kvm_x86_ops svm_x86_ops = {
         .refresh_apicv_exec_ctrl = svm_refresh_apicv_exec_ctrl,
         .load_eoi_exitmap = svm_load_eoi_exitmap,
         .sync_pir_to_irr = svm_sync_pir_to_irr,
+        .hwapic_irr_update = svm_hwapic_irr_update,
+        .hwapic_isr_update = svm_hwapic_isr_update,
 
         .set_tss_addr = svm_set_tss_addr,
         .get_tdp_level = get_npt_level,