KVM/Hyper-V/VMX: Add direct tlb flush support

Hyper-V provides direct tlb flush function which helps
L1 Hypervisor to handle Hyper-V tlb flush request from
L2 guest. Add the function support for VMX.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 3f08327..038581e 100644 (file)
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -181,6 +181,7 @@
 #define HV_X64_ENLIGHTENED_VMCS_RECOMMENDED            BIT(14)
 
 /* Nested features. These are HYPERV_CPUID_NESTED_FEATURES.EAX bits. */
+#define HV_X64_NESTED_DIRECT_FLUSH                     BIT(17)
 #define HV_X64_NESTED_GUEST_MAPPING_FLUSH              BIT(18)
 #define HV_X64_NESTED_MSR_BITMAP                       BIT(19)
 
@@ -892,4 +893,7 @@ struct hv_tlb_flush_ex {
        u64 gva_list[];
 } __packed;
 
+struct hv_partition_assist_pg {
+       u32 tlb_lock_count;
+};
 #endif

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4765ae0..13b35f9 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -844,6 +844,8 @@ struct kvm_hv {
 
        /* How many vCPUs have VP index != vCPU index */
        atomic_t num_mismatched_vp_indexes;
+
+       struct hv_partition_assist_pg *hv_pa_pg;
 };
 
 enum kvm_irqchip_mode {

diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h
index 39a24ee..07ebf68 100644 (file)
--- a/arch/x86/kvm/vmx/evmcs.h
+++ b/arch/x86/kvm/vmx/evmcs.h
@@ -178,6 +178,8 @@ static inline void evmcs_load(u64 phys_addr)
        struct hv_vp_assist_page *vp_ap =
                hv_get_vp_assist_page(smp_processor_id());
 
+       if (current_evmcs->hv_enlightenments_control.nested_flush_hypercall)
+               vp_ap->nested_control.features.directhypercall = 1;
        vp_ap->current_nested_vmcs = phys_addr;
        vp_ap->enlighten_vmentry = 1;
 }

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4a99be1..8bab3e5 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -486,6 +486,35 @@ static int hv_remote_flush_tlb(struct kvm *kvm)
        return hv_remote_flush_tlb_with_range(kvm, NULL);
 }
 
+static int hv_enable_direct_tlbflush(struct kvm_vcpu *vcpu)
+{
+       struct hv_enlightened_vmcs *evmcs;
+       struct hv_partition_assist_pg **p_hv_pa_pg =
+                       &vcpu->kvm->arch.hyperv.hv_pa_pg;
+       /*
+        * Synthetic VM-Exit is not enabled in current code and so All
+        * evmcs in singe VM shares same assist page.
+        */
+       if (!*p_hv_pa_pg) {
+               *p_hv_pa_pg = kzalloc(PAGE_SIZE, GFP_KERNEL);
+               if (!*p_hv_pa_pg)
+                       return -ENOMEM;
+               pr_debug("KVM: Hyper-V: allocated PA_PG for %llx\n",
+                      (u64)&vcpu->kvm);
+       }
+
+       evmcs = (struct hv_enlightened_vmcs *)to_vmx(vcpu)->loaded_vmcs->vmcs;
+
+       evmcs->partition_assist_page =
+               __pa(*p_hv_pa_pg);
+       evmcs->hv_vm_id = (u64)vcpu->kvm;
+       evmcs->hv_enlightenments_control.nested_flush_hypercall = 1;
+
+       pr_debug("KVM: Hyper-V: enabled DIRECT flush for %llx\n",
+                (u64)vcpu->kvm);
+       return 0;
+}
+
 #endif /* IS_ENABLED(CONFIG_HYPERV) */
 
 /*
@@ -6511,6 +6540,9 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
                current_evmcs->hv_clean_fields |=
                        HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL;
 
+       if (static_branch_unlikely(&enable_evmcs))
+               current_evmcs->hv_vp_id = vcpu->arch.hyperv.vp_index;
+
        /* MSR_IA32_DEBUGCTLMSR is zeroed on vmexit. Restore it if needed */
        if (vmx->host_debugctlmsr)
                update_debugctlmsr(vmx->host_debugctlmsr);
@@ -6578,6 +6610,7 @@ static struct kvm *vmx_vm_alloc(void)
 
 static void vmx_vm_free(struct kvm *kvm)
 {
+       kfree(kvm->arch.hyperv.hv_pa_pg);
        vfree(to_kvm_vmx(kvm));
 }
 
@@ -7837,6 +7870,7 @@ static void vmx_exit(void)
                        if (!vp_ap)
                                continue;
 
+                       vp_ap->nested_control.features.directhypercall = 0;
                        vp_ap->current_nested_vmcs = 0;
                        vp_ap->enlighten_vmentry = 0;
                }
@@ -7876,6 +7910,11 @@ static int __init vmx_init(void)
                        pr_info("KVM: vmx: using Hyper-V Enlightened VMCS\n");
                        static_branch_enable(&enable_evmcs);
                }
+
+               if (ms_hyperv.nested_features & HV_X64_NESTED_DIRECT_FLUSH)
+                       vmx_x86_ops.enable_direct_tlbflush
+                               = hv_enable_direct_tlbflush;
+
        } else {
                enlightened_vmcs = false;
        }