[PATCH v7 40/45] arm64: RME: Provide register list for unfinalized RME RECs

Steven Price
2025-02-13T16:17:49Z

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>
---
arch/arm64/kvm/arm.c | 4 ----
arch/arm64/kvm/guest.c | 9 +++------
2 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 0f1d65f87e2b..eeffccc87f19 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1817,10 +1817,6 @@ 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 dd379aba31bb..1288920fc73d 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -671,12 +671,9 @@ static unsigned long num_sve_regs(const struct kvm_vcpu *vcpu)
{
const unsigned int slices = vcpu_sve_slices(vcpu);

- if (!vcpu_has_sve(vcpu))
+ if (!vcpu_has_sve(vcpu) || !kvm_arm_vcpu_sve_finalized(vcpu))
return 0;

- /* Policed by KVM_GET_REG_LIST: */
- WARN_ON(!kvm_arm_vcpu_sve_finalized(vcpu));
-
return slices * (SVE_NUM_PREGS + SVE_NUM_ZREGS + 1 /* FFR */)
+ 1; /* KVM_REG_ARM64_SVE_VLS */
}
@@ -692,8 +689,8 @@ 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));
+ if (!kvm_arm_vcpu_sve_finalized(vcpu))
+ return -EPERM;

/*
* Enumerate this first, so that userspace can save/restore in
--
2.43.0