[PATCH v13 44/48] arm64: RMI: Provide register list for unfinalized RMI RECs

Steven Price
2026-03-18T15:57:05Z

From: Jean-Philippe Brucker <jean-philippe@linaro.org>

KVM_GET_REG_LIST should not be called before SVE is finalized. The ioctl
handler currently returns -EPERM in this case. But because it uses
kvm_arm_vcpu_is_finalized(), it now also rejects the call for
unfinalized REC even though finalizing the REC can only be done late,
after Realm descriptor creation.

Move the check to copy_sve_reg_indices(). One adverse side effect of
this change is that a KVM_GET_REG_LIST call that only probes for the
array size will now succeed even if SVE is not finalized, but that seems
harmless since the following KVM_GET_REG_LIST with the full array will
fail.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Steven Price <steven.price@arm.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
---
arch/arm64/kvm/arm.c | 4 ----
arch/arm64/kvm/guest.c | 10 +++++-----
2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index cd2cb5e54f21..11a816fe981c 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1923,10 +1923,6 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
if (unlikely(!kvm_vcpu_initialized(vcpu)))
break;

- r = -EPERM;
- if (!kvm_arm_vcpu_is_finalized(vcpu))
- break;
-
r = -EFAULT;
if (copy_from_user(&reg_list, user_list, sizeof(reg_list)))
break;
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 999edf0b5219..2c4db2d1a6ca 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -617,8 +617,8 @@ static unsigned long num_sve_regs(const struct kvm_vcpu *vcpu)
if (!vcpu_has_sve(vcpu))
return 0;

- /* Policed by KVM_GET_REG_LIST: */
- WARN_ON(!kvm_arm_vcpu_sve_finalized(vcpu));
+ if (!kvm_arm_vcpu_sve_finalized(vcpu))
+ return 1; /* KVM_REG_ARM64_SVE_VLS */

return slices * (SVE_NUM_PREGS + SVE_NUM_ZREGS + 1 /* FFR */)
+ 1; /* KVM_REG_ARM64_SVE_VLS */
@@ -635,9 +635,6 @@ static int copy_sve_reg_indices(const struct kvm_vcpu *vcpu,
if (!vcpu_has_sve(vcpu))
return 0;

- /* Policed by KVM_GET_REG_LIST: */
- WARN_ON(!kvm_arm_vcpu_sve_finalized(vcpu));
-
/*
* Enumerate this first, so that userspace can save/restore in
* the order reported by KVM_GET_REG_LIST:
@@ -647,6 +644,9 @@ static int copy_sve_reg_indices(const struct kvm_vcpu *vcpu,
return -EFAULT;
++num_regs;

+ if (!kvm_arm_vcpu_sve_finalized(vcpu))
+ return num_regs;
+
for (i = 0; i < slices; i++) {
for (n = 0; n < SVE_NUM_ZREGS; n++) {
reg = KVM_REG_ARM64_SVE_ZREG(n, i);
--
2.43.0