[PATCH v3 1/2] KVM: arm64: Allow userspace to change ID_AA64PFR1_EL1
From: Shaoqin Huang
Date: Fri Jun 28 2024 - 02:05:37 EST
Allow userspace to change the guest-visible value of the register with
some severe limitation:
- No changes to features not virtualized by KVM (MPAM_frac, RAS_frac,
SME, RNDP_trap).
- No changes to features (CSV2_frac, NMI, MTE_frac, GCS, THE, MTEX,
DF2, PFAR) which haven't been added into the ftr_id_aa64pfr1[].
Because the struct arm64_ftr_bits definition for each feature in the
ftr_id_aa64pfr1[] is used by arm64_check_features. If they're not
existing in the ftr_id_aa64pfr1[], the for loop won't check the if
the new_val is safe for those features.
---
arch/arm64/kvm/sys_regs.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 22b45a15d068..159cded22357 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2306,7 +2306,9 @@ static const struct sys_reg_desc sys_reg_descs[] = {
ID_AA64PFR0_EL1_GIC |
ID_AA64PFR0_EL1_AdvSIMD |
ID_AA64PFR0_EL1_FP), },
- ID_SANITISED(ID_AA64PFR1_EL1),
+ ID_WRITABLE(ID_AA64PFR1_EL1, ID_AA64PFR1_EL1_MTE |
+ ID_AA64PFR1_EL1_SSBS |
+ ID_AA64PFR1_EL1_BT),
ID_UNALLOCATED(4,2),
ID_UNALLOCATED(4,3),
ID_WRITABLE(ID_AA64ZFR0_EL1, ~ID_AA64ZFR0_EL1_RES0),
--
2.40.1