KVM: arm64: Allow SMCCC_ARCH_WORKAROUND_3 to be discovered and migrated

KVM allows the guest to discover whether the ARCH_WORKAROUND SMCCC are
implemented, and to preserve that state during migration through its
firmware register interface.

Add the necessary boiler plate for SMCCC_ARCH_WORKAROUND_3.

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>

diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index b3edde6..323e251 100644 (file)
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -281,6 +281,11 @@ struct kvm_arm_copy_mte_tags {
 #define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED       3
 #define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED            (1U << 4)
 
+#define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3    KVM_REG_ARM_FW_REG(3)
+#define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL          0
+#define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_AVAIL              1
+#define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_REQUIRED       2
+
 /* SVE registers */
 #define KVM_REG_ARM64_SVE              (0x15 << KVM_REG_ARM_COPROC_SHIFT)
 

diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 30da78f..202b8c4 100644 (file)
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -107,6 +107,18 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
                                break;
                        }
                        break;
+               case ARM_SMCCC_ARCH_WORKAROUND_3:
+                       switch (arm64_get_spectre_bhb_state()) {
+                       case SPECTRE_VULNERABLE:
+                               break;
+                       case SPECTRE_MITIGATED:
+                               val[0] = SMCCC_RET_SUCCESS;
+                               break;
+                       case SPECTRE_UNAFFECTED:
+                               val[0] = SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED;
+                               break;
+                       }
+                       break;
                case ARM_SMCCC_HV_PV_TIME_FEATURES:
                        val[0] = SMCCC_RET_SUCCESS;
                        break;

diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
index 3eae328..14b9726 100644 (file)
--- a/arch/arm64/kvm/psci.c
+++ b/arch/arm64/kvm/psci.c
@@ -406,7 +406,7 @@ int kvm_psci_call(struct kvm_vcpu *vcpu)
 
 int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
 {
-       return 3;               /* PSCI version and two workaround registers */
+       return 4;               /* PSCI version and three workaround registers */
 }
 
 int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
@@ -420,6 +420,9 @@ int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
        if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2, uindices++))
                return -EFAULT;
 
+       if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3, uindices++))
+               return -EFAULT;
+
        return 0;
 }
 
@@ -459,6 +462,17 @@ static int get_kernel_wa_level(u64 regid)
                case SPECTRE_VULNERABLE:
                        return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
                }
+               break;
+       case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
+               switch (arm64_get_spectre_bhb_state()) {
+               case SPECTRE_VULNERABLE:
+                       return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
+               case SPECTRE_MITIGATED:
+                       return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_AVAIL;
+               case SPECTRE_UNAFFECTED:
+                       return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_REQUIRED;
+               }
+               return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
        }
 
        return -EINVAL;
@@ -475,6 +489,7 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
                break;
        case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
        case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
+       case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
                val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
                break;
        default:
@@ -520,6 +535,7 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
        }
 
        case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
+       case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
                if (val & ~KVM_REG_FEATURE_LEVEL_MASK)
                        return -EINVAL;