Introduce a new capability KVM_CAP_ARM_ID_REG_CONFIGURABLE to indicate
that ID registers are writable by userspace.
Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx>
---
Documentation/virt/kvm/api.rst | 12 ++++++++++++
arch/arm64/kvm/arm.c | 1 +
include/uapi/linux/kvm.h | 1 +
3 files changed, 14 insertions(+)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 9f3172376ec3..d2cd404d74c2 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -2607,6 +2607,10 @@ EINVAL.
After the vcpu's SVE configuration is finalized, further attempts to
write this register will fail with EPERM.
+The arm64 ID registers (where Op0=3, Op1=0, CRn=0, 0<=CRm<8, 0<=Op2<8)
+are allowed to set by userspace if KVM_CAP_ARM_ID_REG_CONFIGURABLE is
+available. They become immutable after calling KVM_RUN on any of the
+vcpus in the guest (modifying values of those registers will fail).
MIPS registers are mapped using the lower 32 bits. The upper 16 of that is
the register group type:
@@ -7575,3 +7579,11 @@ The argument to KVM_ENABLE_CAP is also a bitmask, and must be a subset
of the result of KVM_CHECK_EXTENSION. KVM will forward to userspace
the hypercalls whose corresponding bit is in the argument, and return
ENOSYS for the others.
+
+8.35 KVM_CAP_ARM_ID_REG_CONFIGURABLE
+------------------------------------
+
+:Architectures: arm64
+
+This capability indicates that userspace can modify the ID registers
+via KVM_SET_ONE_REG ioctl.
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index e7dcc7704302..68ffced5b09e 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -210,6 +210,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_SET_GUEST_DEBUG:
case KVM_CAP_VCPU_ATTRIBUTES:
case KVM_CAP_PTP_KVM:
+ case KVM_CAP_ARM_ID_REG_CONFIGURABLE:
r = 1;
break;
case KVM_CAP_SET_GUEST_DEBUG2:
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 507ee1f2aa96..a9351727a7aa 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1135,6 +1135,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_XSAVE2 208
#define KVM_CAP_SYS_ATTRIBUTES 209
#define KVM_CAP_PPC_AIL_MODE_3 210
+#define KVM_CAP_ARM_ID_REG_CONFIGURABLE 211
#ifdef KVM_CAP_IRQ_ROUTING
--
2.35.1.723.g4982287a31-goog
