[PATCH v8 06/29] KVM: arm64: Introduce non-UNDEF FGT control

[Mark Brown <broonie@kernel.org>]

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@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 2f2394cce24e..b501c2880ba2 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -302,6 +302,12 @@ 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 84ec4e100fbb..d5620e02787f 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -283,9 +283,9 @@ static inline void __deactivate_cptr_traps(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)];	\
 		struct fgt_masks *m = reg_to_fgt_masks(reg);		\
 		set |= hfg & m->mask;					\
 		clr |= hfg & m->nmask;					\
@@ -301,7 +301,8 @@ static inline void __deactivate_cptr_traps(struct kvm_vcpu *vcpu)
 		if (is_nested_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);	\
 									\
 		val = m->nmask;						\
 		val |= s;						\

-- 
2.39.5