svm: Introduce AMD IOMMU avic_ga_log_notifier

This patch introduces avic_ga_log_notifier, which will be called
by IOMMU driver whenever it handles the Guest vAPIC (GA) log entry.

Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 69 insertions, 2 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index d36176bb1b6d..4c738c206be3 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -785,6 +785,7 @@ struct kvm_arch {
         u32 ldr_mode;
         struct page *avic_logical_id_table_page;
         struct page *avic_physical_id_table_page;
+        struct hlist_node hnode;
 
         bool x2apic_format;
         bool x2apic_broadcast_quirk_disabled;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 27e37d8044b3..0a9e43b2bd26 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -34,6 +34,8 @@
 #include <linux/sched.h>
 #include <linux/trace_events.h>
 #include <linux/slab.h>
+#include <linux/amd-iommu.h>
+#include <linux/hashtable.h>
 
 #include <asm/apic.h>
 #include <asm/perf_event.h>
@@ -945,6 +947,55 @@ static void svm_disable_lbrv(struct vcpu_svm *svm)
         set_msr_interception(msrpm, MSR_IA32_LASTINTTOIP, 0, 0);
 }
 
+/* Note:
+ * This hash table is used to map VM_ID to a struct kvm_arch,
+ * when handling AMD IOMMU GALOG notification to schedule in
+ * a particular vCPU.
+ */
+#define SVM_VM_DATA_HASH_BITS   8
+DECLARE_HASHTABLE(svm_vm_data_hash, SVM_VM_DATA_HASH_BITS);
+static spinlock_t svm_vm_data_hash_lock;
+
+/* Note:
+ * This function is called from IOMMU driver to notify
+ * SVM to schedule in a particular vCPU of a particular VM.
+ */
+static int avic_ga_log_notifier(u32 ga_tag)
+{
+        unsigned long flags;
+        struct kvm_arch *ka = NULL;
+        struct kvm_vcpu *vcpu = NULL;
+        u32 vm_id = AVIC_GATAG_TO_VMID(ga_tag);
+        u32 vcpu_id = AVIC_GATAG_TO_VCPUID(ga_tag);
+
+        pr_debug("SVM: %s: vm_id=%#x, vcpu_id=%#x\n", __func__, vm_id, vcpu_id);
+
+        spin_lock_irqsave(&svm_vm_data_hash_lock, flags);
+        hash_for_each_possible(svm_vm_data_hash, ka, hnode, vm_id) {
+                struct kvm *kvm = container_of(ka, struct kvm, arch);
+                struct kvm_arch *vm_data = &kvm->arch;
+
+                if (vm_data->avic_vm_id != vm_id)
+                        continue;
+                vcpu = kvm_get_vcpu_by_id(kvm, vcpu_id);
+                break;
+        }
+        spin_unlock_irqrestore(&svm_vm_data_hash_lock, flags);
+
+        if (!vcpu)
+                return 0;
+
+        /* Note:
+         * At this point, the IOMMU should have already set the pending
+         * bit in the vAPIC backing page. So, we just need to schedule
+         * in the vcpu.
+         */
+        if (vcpu->mode == OUTSIDE_GUEST_MODE)
+                kvm_vcpu_wake_up(vcpu);
+
+        return 0;
+}
+
 static __init int svm_hardware_setup(void)
 {
         int cpu;
@@ -1003,10 +1054,15 @@ static __init int svm_hardware_setup(void)
         if (avic) {
                 if (!npt_enabled ||
                     !boot_cpu_has(X86_FEATURE_AVIC) ||
-                    !IS_ENABLED(CONFIG_X86_LOCAL_APIC))
+                    !IS_ENABLED(CONFIG_X86_LOCAL_APIC)) {
                         avic = false;
-                else
+                } else {
                         pr_info("AVIC enabled\n");
+
+                        hash_init(svm_vm_data_hash);
+                        spin_lock_init(&svm_vm_data_hash_lock);
+                        amd_iommu_register_ga_log_notifier(&avic_ga_log_notifier);
+                }
         }
 
         return 0;
@@ -1327,6 +1383,7 @@ static inline int avic_free_vm_id(int id)
 
 static void avic_vm_destroy(struct kvm *kvm)
 {
+        unsigned long flags;
         struct kvm_arch *vm_data = &kvm->arch;
 
         avic_free_vm_id(vm_data->avic_vm_id);
@@ -1335,10 +1392,15 @@ static void avic_vm_destroy(struct kvm *kvm)
                 __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);
+
+        spin_lock_irqsave(&svm_vm_data_hash_lock, flags);
+        hash_del(&vm_data->hnode);
+        spin_unlock_irqrestore(&svm_vm_data_hash_lock, flags);
 }
 
 static int avic_vm_init(struct kvm *kvm)
 {
+        unsigned long flags;
         int err = -ENOMEM;
         struct kvm_arch *vm_data = &kvm->arch;
         struct page *p_page;
@@ -1367,6 +1429,10 @@ static int avic_vm_init(struct kvm *kvm)
         vm_data->avic_logical_id_table_page = l_page;
         clear_page(page_address(l_page));
 
+        spin_lock_irqsave(&svm_vm_data_hash_lock, flags);
+        hash_add(svm_vm_data_hash, &vm_data->hnode, vm_data->avic_vm_id);
+        spin_unlock_irqrestore(&svm_vm_data_hash_lock, flags);
+
         return 0;
 
 free_avic: