All vCPUs that are owned by a VM must have the same values of ID
registers.
Return an error at the very first KVM_RUN for a vCPU if the vCPU has
different values in any ID registers from any other vCPUs that have
already started KVM_RUN once. Also, return an error if userspace
tries to change a value of ID register for a vCPU that already
started KVM_RUN once.
Changing ID register is still not allowed at present though.
Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_host.h | 2 ++
arch/arm64/kvm/arm.c | 4 ++++
arch/arm64/kvm/sys_regs.c | 31 +++++++++++++++++++++++++++++++
3 files changed, 37 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 0cd351099adf..69af669308b0 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -745,6 +745,8 @@ int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu,
long kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm,
struct kvm_arm_copy_mte_tags *copy_tags);
+int kvm_id_regs_consistency_check(const struct kvm_vcpu *vcpu);
+
/* Guest/host FPSIMD coordination helpers */
int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index fe102cd2e518..83cedd74de73 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -595,6 +595,10 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu)
return -EPERM;
vcpu->arch.has_run_once = true;
+ if (kvm_id_regs_consistency_check(vcpu)) {
+ vcpu->arch.has_run_once = false;
+ return -EPERM;
+ }
kvm_arm_vcpu_init_debug(vcpu);
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 64d51aa3aee3..e34351fdc66c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1436,6 +1436,10 @@ static int __set_id_reg(struct kvm_vcpu *vcpu,
if (val != read_id_reg(vcpu, rd, raz) && !GET_ID_REG_INFO(encoding))
return -EINVAL;
+ /* Don't allow to change the reg after the first KVM_RUN. */
+ if (vcpu->arch.has_run_once)
+ return -EINVAL;
+
if (raz)
return 0;
@@ -3004,6 +3008,33 @@ int kvm_arm_copy_sys_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
return write_demux_regids(uindices);
}
+int kvm_id_regs_consistency_check(const struct kvm_vcpu *vcpu)
+{
+ int i;
+ const struct kvm_vcpu *t_vcpu;
+
+ /*
+ * Make sure vcpu->arch.has_run_once is visible for others so that
+ * ID regs' consistency between two vCPUs is checked by either one
+ * at least.
+ */
+ smp_mb();
+ WARN_ON(!vcpu->arch.has_run_once);
+
+ kvm_for_each_vcpu(i, t_vcpu, vcpu->kvm) {
+ if (!t_vcpu->arch.has_run_once)
+ /* ID regs still could be updated. */
+ continue;
+
+ if (memcmp(&__vcpu_sys_reg(vcpu, ID_REG_BASE),
+ &__vcpu_sys_reg(t_vcpu, ID_REG_BASE),
+ sizeof(__vcpu_sys_reg(vcpu, ID_REG_BASE)) *
+ KVM_ARM_ID_REG_MAX_NUM))
+ return -EINVAL;
+ }
+ return 0;
+}
+
static void id_reg_info_init_all(void)
{
int i;
--
2.33.1.1089.g2158813163f-goog
