KVM: arm64: Add standard hypervisor firmware register

Introduce the firmware register to hold the standard hypervisor
service calls (owner value 5) as a bitmap. The bitmap represents
the features that'll be enabled for the guest, as configured by
the user-space. Currently, this includes support only for
Paravirtualized time, represented by bit-0.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
[maz: tidy-up bitmap values]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220502233853.1233742-4-rananta@google.com

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index fef597a..281dfcf 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -105,9 +105,11 @@ struct kvm_arch_memory_slot {
  * struct kvm_smccc_features: Descriptor of the hypercall services exposed to the guests
  *
  * @std_bmap: Bitmap of standard secure service calls
+ * @std_hyp_bmap: Bitmap of standard hypervisor service calls
  */
 struct kvm_smccc_features {
        unsigned long std_bmap;
+       unsigned long std_hyp_bmap;
 };
 
 struct kvm_arch {

diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index b0be5ec..7ff5a2c 100644 (file)
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -345,6 +345,13 @@ enum {
        KVM_REG_ARM_STD_BMAP_BIT_COUNT,
 };
 
+#define KVM_REG_ARM_STD_HYP_BMAP               KVM_REG_ARM_FW_FEAT_BMAP_REG(1)
+
+enum {
+       KVM_REG_ARM_STD_HYP_BIT_PV_TIME = 0,
+       KVM_REG_ARM_STD_HYP_BMAP_BIT_COUNT,
+};
+
 /* Device Control API: ARM VGIC */
 #define KVM_DEV_ARM_VGIC_GRP_ADDR      0
 #define KVM_DEV_ARM_VGIC_GRP_DIST_REGS 1

diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 22f3a91..c43f78c 100644 (file)
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -11,6 +11,8 @@
 
 #define KVM_ARM_SMCCC_STD_FEATURES                             \
        GENMASK(KVM_REG_ARM_STD_BMAP_BIT_COUNT - 1, 0)
+#define KVM_ARM_SMCCC_STD_HYP_FEATURES                         \
+       GENMASK(KVM_REG_ARM_STD_HYP_BMAP_BIT_COUNT - 1, 0)
 
 static void kvm_ptp_get_time(struct kvm_vcpu *vcpu, u64 *val)
 {
@@ -71,8 +73,6 @@ static bool kvm_hvc_call_default_allowed(u32 func_id)
         */
        case ARM_SMCCC_VERSION_FUNC_ID:
        case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
-       case ARM_SMCCC_HV_PV_TIME_FEATURES:
-       case ARM_SMCCC_HV_PV_TIME_ST:
        case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
        case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
        case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
@@ -106,6 +106,10 @@ static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
        case ARM_SMCCC_TRNG_RND64:
                return test_bit(KVM_REG_ARM_STD_BIT_TRNG_V1_0,
                                &smccc_feat->std_bmap);
+       case ARM_SMCCC_HV_PV_TIME_FEATURES:
+       case ARM_SMCCC_HV_PV_TIME_ST:
+               return test_bit(KVM_REG_ARM_STD_HYP_BIT_PV_TIME,
+                               &smccc_feat->std_hyp_bmap);
        default:
                return kvm_hvc_call_default_allowed(func_id);
        }
@@ -113,6 +117,7 @@ static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
 
 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 {
+       struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
        u32 func_id = smccc_get_function(vcpu);
        u64 val[4] = {SMCCC_RET_NOT_SUPPORTED};
        u32 feature;
@@ -176,7 +181,9 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
                        }
                        break;
                case ARM_SMCCC_HV_PV_TIME_FEATURES:
-                       val[0] = SMCCC_RET_SUCCESS;
+                       if (test_bit(KVM_REG_ARM_STD_HYP_BIT_PV_TIME,
+                                    &smccc_feat->std_hyp_bmap))
+                               val[0] = SMCCC_RET_SUCCESS;
                        break;
                }
                break;
@@ -222,6 +229,7 @@ static const u64 kvm_arm_fw_reg_ids[] = {
        KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
        KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
        KVM_REG_ARM_STD_BMAP,
+       KVM_REG_ARM_STD_HYP_BMAP,
 };
 
 void kvm_arm_init_hypercalls(struct kvm *kvm)
@@ -229,6 +237,7 @@ void kvm_arm_init_hypercalls(struct kvm *kvm)
        struct kvm_smccc_features *smccc_feat = &kvm->arch.smccc_feat;
 
        smccc_feat->std_bmap = KVM_ARM_SMCCC_STD_FEATURES;
+       smccc_feat->std_hyp_bmap = KVM_ARM_SMCCC_STD_HYP_FEATURES;
 }
 
 int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
@@ -317,6 +326,9 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
        case KVM_REG_ARM_STD_BMAP:
                val = READ_ONCE(smccc_feat->std_bmap);
                break;
+       case KVM_REG_ARM_STD_HYP_BMAP:
+               val = READ_ONCE(smccc_feat->std_hyp_bmap);
+               break;
        default:
                return -ENOENT;
        }
@@ -339,6 +351,10 @@ static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
                fw_reg_bmap = &smccc_feat->std_bmap;
                fw_reg_features = KVM_ARM_SMCCC_STD_FEATURES;
                break;
+       case KVM_REG_ARM_STD_HYP_BMAP:
+               fw_reg_bmap = &smccc_feat->std_hyp_bmap;
+               fw_reg_features = KVM_ARM_SMCCC_STD_HYP_FEATURES;
+               break;
        default:
                return -ENOENT;
        }
@@ -439,6 +455,7 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 
                return 0;
        case KVM_REG_ARM_STD_BMAP:
+       case KVM_REG_ARM_STD_HYP_BMAP:
                return kvm_arm_set_fw_reg_bmap(vcpu, reg->id, val);
        default:
                return -ENOENT;