Currently, the sizes of all pseudo firmware registers are 64 bits.
The value from user space is copied to a local 64-bits variable,
which is passed on in kvm_arm_set_fw_reg(). It works perfectly
until large sized pseudo firmware registers are added for SDEI
event handlers, states and context.

This copies the user space's value to local 64-bits variable
and passes the local variable on, only if the pseudo firmware
register is 64-bits in size. No functional change intended.

Signed-off-by: Gavin Shan <gs...@redhat.com>
---
 arch/arm64/kvm/hypercalls.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index aaa5197ffe83..8e0df54d1422 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -406,14 +406,20 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const 
struct kvm_one_reg *reg)
        return 0;
 }
 
-static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
+static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu,
+                                  const struct kvm_one_reg *reg)
 {
        int ret = 0;
        struct kvm *kvm = vcpu->kvm;
        struct kvm_smccc_features *smccc_feat = &kvm->arch.smccc_feat;
        unsigned long *fw_reg_bmap, fw_reg_features;
+       void __user *uaddr = (void __user *)(long)reg->addr;
+       u64 val;
 
-       switch (reg_id) {
+       if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
+               return -EFAULT;
+
+       switch (reg->id) {
        case KVM_REG_ARM_STD_BMAP:
                fw_reg_bmap = &smccc_feat->std_bmap;
                fw_reg_features = KVM_ARM_SMCCC_STD_FEATURES;
@@ -454,15 +460,14 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const 
struct kvm_one_reg *reg)
        u64 val;
        int wa_level;
 
-       if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
-               return -EFAULT;
-
        switch (reg->id) {
        case KVM_REG_ARM_PSCI_VERSION:
        {
                bool wants_02;
 
                wants_02 = test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features);
+               if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
+                       return -EFAULT;
 
                switch (val) {
                case KVM_ARM_PSCI_0_1:
@@ -483,6 +488,9 @@ 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 (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
+                       return -EFAULT;
+
                if (val & ~KVM_REG_FEATURE_LEVEL_MASK)
                        return -EINVAL;
 
@@ -492,6 +500,9 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct 
kvm_one_reg *reg)
                return 0;
 
        case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
+               if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
+                       return -EFAULT;
+
                if (val & ~(KVM_REG_FEATURE_LEVEL_MASK |
                            KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED))
                        return -EINVAL;
@@ -529,7 +540,7 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct 
kvm_one_reg *reg)
        case KVM_REG_ARM_STD_BMAP:
        case KVM_REG_ARM_STD_HYP_BMAP:
        case KVM_REG_ARM_VENDOR_HYP_BMAP:
-               return kvm_arm_set_fw_reg_bmap(vcpu, reg->id, val);
+               return kvm_arm_set_fw_reg_bmap(vcpu, reg);
        default:
                return -ENOENT;
        }
-- 
2.23.0

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