Commit f5a5a406 authored by Marc Zyngier's avatar Marc Zyngier Committed by Oliver Upton
Browse files

KVM: arm64: Propagate and handle Fine-Grained UNDEF bits 



In order to correctly honor our FGU bits, they must be converted
into a set of FGT bits. They get merged as part of the existing
FGT setting.

Similarly, the UNDEF injection phase takes place when handling
the trap.

This results in a bit of rework in the FGT macros in order to
help with the code generation, as burying per-CPU accesses in
macros results in a lot of expansion, not to mention the vcpu->kvm
access on nvhe (kern_hyp_va() is not optimisation-friendly).

Reviewed-by: default avatarJoey Gouly <joey.gouly@arm.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240214131827.2856277-19-maz@kernel.org


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 2fd8f31c

arch/arm64/kvm/emulate-nested.c

+11 −0
Original line number Diff line number Diff line
@@ -2017,6 +2017,17 @@ bool triage_sysreg_trap(struct kvm_vcpu *vcpu, int *sr_index) 
	if (!tc.val)

		goto local;



	/*

	 * If a sysreg can be trapped using a FGT, first check whether we

	 * trap for the purpose of forbidding the feature. In that case,

	 * inject an UNDEF.

	 */

	if (tc.fgt != __NO_FGT_GROUP__ &&

	    (vcpu->kvm->arch.fgu[tc.fgt] & BIT(tc.bit))) {

		kvm_inject_undefined(vcpu);

		return true;

	}



	/*

	 * If we're not nesting, immediately return to the caller, with the

	 * sysreg index, should we have it.

arch/arm64/kvm/hyp/include/hyp/switch.h

+61 −20
Original line number Diff line number Diff line
@@ -79,14 +79,48 @@ static inline void __activate_traps_fpsimd32(struct kvm_vcpu *vcpu) 
		clr |= ~hfg & __ ## reg ## _nMASK; 			\

	} while(0)



#define update_fgt_traps_cs(vcpu, reg, clr, set)			\

#define reg_to_fgt_group_id(reg)					\

	({								\

		enum fgt_group_id id;					\

		switch(reg) {						\

		case HFGRTR_EL2:					\

		case HFGWTR_EL2:					\

			id = HFGxTR_GROUP;				\

			break;						\

		case HFGITR_EL2:					\

			id = HFGITR_GROUP;				\

			break;						\

		case HDFGRTR_EL2:					\

		case HDFGWTR_EL2:					\

			id = HDFGRTR_GROUP;				\

			break;						\

		case HAFGRTR_EL2:					\

			id = HAFGRTR_GROUP;				\

			break;						\

		default:						\

			BUILD_BUG_ON(1);				\

		}							\

									\

		id;							\

	})



#define compute_undef_clr_set(vcpu, kvm, reg, clr, set)			\

	do {								\

		u64 hfg = kvm->arch.fgu[reg_to_fgt_group_id(reg)];	\

		set |= hfg & __ ## reg ## _MASK;			\

		clr |= hfg & __ ## reg ## _nMASK; 			\

	} while(0)



#define update_fgt_traps_cs(hctxt, vcpu, kvm, reg, clr, set)		\

	do {								\

		struct kvm_cpu_context *hctxt =				\

			&this_cpu_ptr(&kvm_host_data)->host_ctxt;	\

		u64 c = 0, s = 0;					\

									\

		ctxt_sys_reg(hctxt, reg) = read_sysreg_s(SYS_ ## reg);	\

		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);		\

									\

		s |= set;						\

		c |= clr;						\

		if (c || s) {						\
@@ -97,8 +131,8 @@ static inline void __activate_traps_fpsimd32(struct kvm_vcpu *vcpu) 
		}							\

	} while(0)



#define update_fgt_traps(vcpu, reg)		\

	update_fgt_traps_cs(vcpu, reg, 0, 0)

#define update_fgt_traps(hctxt, vcpu, kvm, reg)		\

	update_fgt_traps_cs(hctxt, vcpu, kvm, reg, 0, 0)



/*

 * Validate the fine grain trap masks.
@@ -122,6 +156,7 @@ static inline bool cpu_has_amu(void) 
static inline void __activate_traps_hfgxtr(struct kvm_vcpu *vcpu)

{

	struct kvm_cpu_context *hctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;

	struct kvm *kvm = kern_hyp_va(vcpu->kvm);

	u64 r_clr = 0, w_clr = 0, r_set = 0, w_set = 0, tmp;

	u64 r_val, w_val;
@@ -157,6 +192,9 @@ static inline void __activate_traps_hfgxtr(struct kvm_vcpu *vcpu) 
		compute_clr_set(vcpu, HFGWTR_EL2, w_clr, w_set);

	}



	compute_undef_clr_set(vcpu, kvm, HFGRTR_EL2, r_clr, r_set);

	compute_undef_clr_set(vcpu, kvm, HFGWTR_EL2, w_clr, w_set);



	/* The default to trap everything not handled or supported in KVM. */

	tmp = HFGxTR_EL2_nAMAIR2_EL1 | HFGxTR_EL2_nMAIR2_EL1 | HFGxTR_EL2_nS2POR_EL1 |

	      HFGxTR_EL2_nPOR_EL1 | HFGxTR_EL2_nPOR_EL0 | HFGxTR_EL2_nACCDATA_EL1;
@@ -172,20 +210,26 @@ static inline void __activate_traps_hfgxtr(struct kvm_vcpu *vcpu) 
	write_sysreg_s(r_val, SYS_HFGRTR_EL2);

	write_sysreg_s(w_val, SYS_HFGWTR_EL2);



	if (!vcpu_has_nv(vcpu) || is_hyp_ctxt(vcpu))

		return;



	update_fgt_traps(vcpu, HFGITR_EL2);

	update_fgt_traps(vcpu, HDFGRTR_EL2);

	update_fgt_traps(vcpu, HDFGWTR_EL2);

	update_fgt_traps(hctxt, vcpu, kvm, HFGITR_EL2);

	update_fgt_traps(hctxt, vcpu, kvm, HDFGRTR_EL2);

	update_fgt_traps(hctxt, vcpu, kvm, HDFGWTR_EL2);



	if (cpu_has_amu())

		update_fgt_traps(vcpu, HAFGRTR_EL2);

		update_fgt_traps(hctxt, vcpu, kvm, HAFGRTR_EL2);

}



#define __deactivate_fgt(htcxt, vcpu, kvm, reg)				\

	do {								\

		if ((vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu)) ||	\

		    kvm->arch.fgu[reg_to_fgt_group_id(reg)])		\

			write_sysreg_s(ctxt_sys_reg(hctxt, reg),	\

				       SYS_ ## reg);			\

	} while(0)



static inline void __deactivate_traps_hfgxtr(struct kvm_vcpu *vcpu)

{

	struct kvm_cpu_context *hctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;

	struct kvm *kvm = kern_hyp_va(vcpu->kvm);



	if (!cpus_have_final_cap(ARM64_HAS_FGT))

		return;
@@ -193,15 +237,12 @@ static inline void __deactivate_traps_hfgxtr(struct kvm_vcpu *vcpu) 
	write_sysreg_s(ctxt_sys_reg(hctxt, HFGRTR_EL2), SYS_HFGRTR_EL2);

	write_sysreg_s(ctxt_sys_reg(hctxt, HFGWTR_EL2), SYS_HFGWTR_EL2);



	if (!vcpu_has_nv(vcpu) || is_hyp_ctxt(vcpu))

		return;



	write_sysreg_s(ctxt_sys_reg(hctxt, HFGITR_EL2), SYS_HFGITR_EL2);

	write_sysreg_s(ctxt_sys_reg(hctxt, HDFGRTR_EL2), SYS_HDFGRTR_EL2);

	write_sysreg_s(ctxt_sys_reg(hctxt, HDFGWTR_EL2), SYS_HDFGWTR_EL2);

	__deactivate_fgt(hctxt, vcpu, kvm, HFGITR_EL2);

	__deactivate_fgt(hctxt, vcpu, kvm, HDFGRTR_EL2);

	__deactivate_fgt(hctxt, vcpu, kvm, HDFGWTR_EL2);



	if (cpu_has_amu())

		write_sysreg_s(ctxt_sys_reg(hctxt, HAFGRTR_EL2), SYS_HAFGRTR_EL2);

		__deactivate_fgt(hctxt, vcpu, kvm, HAFGRTR_EL2);

}



static inline void __activate_traps_common(struct kvm_vcpu *vcpu)