[PATCH v5 05/28] KVM: arm64: Introduce non-UNDEF FGT control

[Mark Brown]

We have support for determining a set of fine grained traps to enable for
the guest which is tied to the support for injecting UNDEFs for undefined
features. This means that we can't use the mechanism for system registers
which should be present but need emulation, such as SMPRI_EL1 which should
be accessible when SME is present but if SME priority support is absent
SMPRI_EL1.Priority should be RAZ.

Add an additional set of fine grained traps fgt, mirroring the existing fgu
array. We use the same format where we always set the bit for the trap in
the array as for FGU. This makes it clear what is being explicitly managed
and keeps the code consistent.

We do not convert the handling of ARM_WORKAROUND_AMPERE_ACO3_CPU_38 to this
mechanism since this only enables a write trap and when implementing the
existing UNDEF that we would share the read and write trap enablement (this
being the overwhelmingly common case).

Signed-off-by: Mark Brown <broonie at kernel.org>
---
 arch/arm64/include/asm/kvm_host.h       | 6 ++++++
 arch/arm64/kvm/hyp/include/hyp/switch.h | 7 ++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index e98cfe7855a6..3fc8260d55a6 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -295,6 +295,12 @@ struct kvm_arch {
 	 */
 	u64 fgu[__NR_FGT_GROUP_IDS__];
 
+	/*
+	 * Additional FGTs to enable for the guests, eg. for emulated
+	 * registers,
+	 */
+	u64 fgt[__NR_FGT_GROUP_IDS__];
+
 	/*
 	 * Stage 2 paging state for VMs with nested S2 using a virtual
 	 * VMID.
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index b741ea6aefa5..7c9355459648 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -98,9 +98,9 @@ static inline void __activate_traps_fpsimd32(struct kvm_vcpu *vcpu)
 		id;							\
 	})
 
-#define compute_undef_clr_set(vcpu, kvm, reg, clr, set)			\
+#define compute_trap_clr_set(vcpu, kvm, trap, reg, clr, set)		\
 	do {								\
-		u64 hfg = kvm->arch.fgu[reg_to_fgt_group_id(reg)];	\
+		u64 hfg = kvm->arch.trap[reg_to_fgt_group_id(reg)];	\
 		set |= hfg & __ ## reg ## _MASK;			\
 		clr |= hfg & __ ## reg ## _nMASK; 			\
 	} while(0)
@@ -113,7 +113,8 @@ static inline void __activate_traps_fpsimd32(struct kvm_vcpu *vcpu)
 		if (vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu))		\
 			compute_clr_set(vcpu, reg, c, s);		\
 									\
-		compute_undef_clr_set(vcpu, kvm, reg, c, s);		\
+		compute_trap_clr_set(vcpu, kvm, fgu, reg, c, s);	\
+		compute_trap_clr_set(vcpu, kvm, fgt, reg, c, s);	\
 									\
 		s |= set;						\
 		c |= clr;						\

-- 
2.39.5