From: Jing Zhang <jingzhangos@xxxxxxxxxx>
Allow userspace to change the guest-visible value of the register with
some severe limitation:
- No changes to features not virtualized by KVM (AMU, MPAM, RAS)
- Short of full GICv2 emulation in kernel, hiding GICv3 from the guest
makes absolutely no sense.
- FP is effectively assumed for KVM VMs.
Signed-off-by: Jing Zhang <jingzhangos@xxxxxxxxxx>
[oliver: restrict features that are illogical to change]
Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
---
arch/arm64/kvm/sys_regs.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 5758cff479d3..8738b0a0cf5c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2061,7 +2061,13 @@ static const struct sys_reg_desc sys_reg_descs[] = {
.get_user = get_id_reg,
.set_user = set_id_reg,
.reset = read_sanitised_id_aa64pfr0_el1,
- .val = ID_AA64PFR0_EL1_CSV2_MASK | ID_AA64PFR0_EL1_CSV3_MASK, },
+ .val = ~(ID_AA64PFR0_EL1_AMU |
+ ID_AA64PFR0_EL1_MPAM |
+ ID_AA64PFR0_EL1_SVE |
+ ID_AA64PFR0_EL1_RAS |
+ ID_AA64PFR0_EL1_GIC |
+ ID_AA64PFR0_EL1_AdvSIMD |
+ ID_AA64PFR0_EL1_FP), },
ID_SANITISED(ID_AA64PFR1_EL1),
ID_UNALLOCATED(4,2),
ID_UNALLOCATED(4,3),
--
2.42.0.515.g380fc7ccd1-goog
