diff mbox series

[v10,08/12] KVM: arm64: Allow userspace to change ID_AA64PFR0_EL1

Message ID 20230920183310.1163034-9-oliver.upton@linux.dev (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: Enable 'writable' ID registers | expand

Commit Message

Oliver Upton Sept. 20, 2023, 6:33 p.m. UTC 
From: Jing Zhang <jingzhangos@google.com>

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@google.com>
[oliver: restrict features that are illogical to change]
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/arm64/kvm/sys_regs.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
diff mbox series

Patch

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),