From: Mark Brown <broonie@xxxxxxxxxx>
When the guest does not support FEAT_TCR2 we should not allow any access
to it in order to ensure that we do not create spurious issues with guest
migration. Add a visibility operation for it.
Fixes: fbff56068232 ("KVM: arm64: Save/restore TCR2_EL1")
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240822-kvm-arm64-hide-pie-regs-v2-2-376624fa829c@xxxxxxxxxx
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_host.h | 3 +++
arch/arm64/kvm/sys_regs.c | 29 ++++++++++++++++++++++++++---
2 files changed, 29 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index ab4c675b491d..7889e5f4009f 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -1476,4 +1476,7 @@ void kvm_set_vm_id_reg(struct kvm *kvm, u32 reg, u64 val);
(pa + pi + pa3) == 1; \
})
+#define kvm_has_tcr2(k) \
+ (kvm_has_feat((k), ID_AA64MMFR3_EL1, TCRX, IMP))
+
#endif /* __ARM64_KVM_HOST_H__ */
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 4ee74e2d4f08..64562b0c2359 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2319,6 +2319,27 @@ static bool access_zcr_el2(struct kvm_vcpu *vcpu,
return true;
}
+static unsigned int tcr2_visibility(const struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd)
+{
+ if (kvm_has_tcr2(vcpu->kvm))
+ return 0;
+
+ return REG_HIDDEN;
+}
+
+static unsigned int tcr2_el2_visibility(const struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd)
+{
+ unsigned int r;
+
+ r = el2_visibility(vcpu, rd);
+ if (r)
+ return r;
+
+ return tcr2_visibility(vcpu, rd);
+}
+
/*
* Architected system registers.
* Important: Must be sorted ascending by Op0, Op1, CRn, CRm, Op2
@@ -2503,7 +2524,8 @@ static const struct sys_reg_desc sys_reg_descs[] = {
{ SYS_DESC(SYS_TTBR0_EL1), access_vm_reg, reset_unknown, TTBR0_EL1 },
{ SYS_DESC(SYS_TTBR1_EL1), access_vm_reg, reset_unknown, TTBR1_EL1 },
{ SYS_DESC(SYS_TCR_EL1), access_vm_reg, reset_val, TCR_EL1, 0 },
- { SYS_DESC(SYS_TCR2_EL1), access_vm_reg, reset_val, TCR2_EL1, 0 },
+ { SYS_DESC(SYS_TCR2_EL1), access_vm_reg, reset_val, TCR2_EL1, 0,
+ .visibility = tcr2_visibility },
PTRAUTH_KEY(APIA),
PTRAUTH_KEY(APIB),
@@ -2820,7 +2842,8 @@ static const struct sys_reg_desc sys_reg_descs[] = {
EL2_REG(TTBR0_EL2, access_rw, reset_val, 0),
EL2_REG(TTBR1_EL2, access_rw, reset_val, 0),
EL2_REG(TCR_EL2, access_rw, reset_val, TCR_EL2_RES1),
- EL2_REG(TCR2_EL2, access_tcr2_el2, reset_val, TCR2_EL2_RES1),
+ EL2_REG_FILTERED(TCR2_EL2, access_tcr2_el2, reset_val, TCR2_EL2_RES1,
+ tcr2_el2_visibility),
EL2_REG_VNCR(VTTBR_EL2, reset_val, 0),
EL2_REG_VNCR(VTCR_EL2, reset_val, 0),
@@ -4679,7 +4702,7 @@ void kvm_calculate_traps(struct kvm_vcpu *vcpu)
if (kvm_has_feat(kvm, ID_AA64ISAR2_EL1, MOPS, IMP))
vcpu->arch.hcrx_el2 |= (HCRX_EL2_MSCEn | HCRX_EL2_MCE2);
- if (kvm_has_feat(kvm, ID_AA64MMFR3_EL1, TCRX, IMP))
+ if (kvm_has_tcr2(kvm))
vcpu->arch.hcrx_el2 |= HCRX_EL2_TCR2En;
}
--
2.39.2
