KVM: arm64: Allow userspace to change ID_AA64MMFR{0-2}_EL1

Allow userspace to modify the guest-visible values of these ID
registers. Prevent changes to any of the virtualization features until
KVM picks up support for nested and we have a handle on managing NV
features.

Signed-off-by: Jing Zhang <jingzhangos@google.com>
[oliver: prevent changes to EL2 features for now]
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231003230408.3405722-8-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 5d1a94af42f27b22d6134e080f98b91f0761ce25..d850b05eb5042282b403018ba65a140aafdf38ab 100644 (file)
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2099,9 +2099,23 @@ static const struct sys_reg_desc sys_reg_descs[] = {
        ID_UNALLOCATED(6,7),
 
        /* CRm=7 */
-       ID_SANITISED(ID_AA64MMFR0_EL1),
-       ID_SANITISED(ID_AA64MMFR1_EL1),
-       ID_SANITISED(ID_AA64MMFR2_EL1),
+       ID_WRITABLE(ID_AA64MMFR0_EL1, ~(ID_AA64MMFR0_EL1_RES0 |
+                                       ID_AA64MMFR0_EL1_TGRAN4_2 |
+                                       ID_AA64MMFR0_EL1_TGRAN64_2 |
+                                       ID_AA64MMFR0_EL1_TGRAN16_2)),
+       ID_WRITABLE(ID_AA64MMFR1_EL1, ~(ID_AA64MMFR1_EL1_RES0 |
+                                       ID_AA64MMFR1_EL1_HCX |
+                                       ID_AA64MMFR1_EL1_XNX |
+                                       ID_AA64MMFR1_EL1_TWED |
+                                       ID_AA64MMFR1_EL1_XNX |
+                                       ID_AA64MMFR1_EL1_VH |
+                                       ID_AA64MMFR1_EL1_VMIDBits)),
+       ID_WRITABLE(ID_AA64MMFR2_EL1, ~(ID_AA64MMFR2_EL1_RES0 |
+                                       ID_AA64MMFR2_EL1_EVT |
+                                       ID_AA64MMFR2_EL1_FWB |
+                                       ID_AA64MMFR2_EL1_IDS |
+                                       ID_AA64MMFR2_EL1_NV |
+                                       ID_AA64MMFR2_EL1_CCIDX)),
        ID_SANITISED(ID_AA64MMFR3_EL1),
        ID_UNALLOCATED(7,4),
        ID_UNALLOCATED(7,5),