Commit cc5f84fb authored by Marc Zyngier's avatar Marc Zyngier Committed by Oliver Upton
Browse files

KVM: arm64: Use the xarray as the primary sysreg/sysinsn walker 



Since we always start sysreg/sysinsn handling by searching the
xarray, use it as the source of the index in the correct sys_reg_desc
array.

This allows some cleanup, such as moving the handling of unknown
sysregs in a single location.

Reviewed-by: default avatarJoey Gouly <joey.gouly@arm.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240214131827.2856277-16-maz@kernel.org


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 19f3e7ea

arch/arm64/include/asm/kvm_nested.h

+1 −1
Original line number Diff line number Diff line
@@ -60,7 +60,7 @@ static inline u64 translate_ttbr0_el2_to_ttbr0_el1(u64 ttbr0) 
	return ttbr0 & ~GENMASK_ULL(63, 48);

}



extern bool __check_nv_sr_forward(struct kvm_vcpu *vcpu);

extern bool __check_nv_sr_forward(struct kvm_vcpu *vcpu, int *sr_idx);



int kvm_init_nv_sysregs(struct kvm *kvm);

arch/arm64/kvm/emulate-nested.c

+30 −10
Original line number Diff line number Diff line
@@ -2007,7 +2007,7 @@ static bool check_fgt_bit(struct kvm *kvm, bool is_read, 
	return !(kvm_get_sysreg_res0(kvm, sr) & BIT(tc.bit));

}



bool __check_nv_sr_forward(struct kvm_vcpu *vcpu)

bool __check_nv_sr_forward(struct kvm_vcpu *vcpu, int *sr_index)

{

	union trap_config tc;

	enum trap_behaviour b;
@@ -2015,9 +2015,6 @@ bool __check_nv_sr_forward(struct kvm_vcpu *vcpu) 
	u32 sysreg;

	u64 esr, val;



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

		return false;



	esr = kvm_vcpu_get_esr(vcpu);

	sysreg = esr_sys64_to_sysreg(esr);

	is_read = (esr & ESR_ELx_SYS64_ISS_DIR_MASK) == ESR_ELx_SYS64_ISS_DIR_READ;
@@ -2028,13 +2025,16 @@ bool __check_nv_sr_forward(struct kvm_vcpu *vcpu) 
	 * A value of 0 for the whole entry means that we know nothing

	 * for this sysreg, and that it cannot be re-injected into the

	 * nested hypervisor. In this situation, let's cut it short.

	 *

	 * Note that ultimately, we could also make use of the xarray

	 * to store the index of the sysreg in the local descriptor

	 * array, avoiding another search... Hint, hint...

	 */

	if (!tc.val)

		return false;

		goto local;



	/*

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

	 * sysreg index, should we have it.

	 */

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

		goto local;



	switch ((enum fgt_group_id)tc.fgt) {

	case __NO_FGT_GROUP__:
@@ -2076,7 +2076,7 @@ bool __check_nv_sr_forward(struct kvm_vcpu *vcpu) 
	case __NR_FGT_GROUP_IDS__:

		/* Something is really wrong, bail out */

		WARN_ONCE(1, "__NR_FGT_GROUP_IDS__");

		return false;

		goto local;

	}



	if (tc.fgt != __NO_FGT_GROUP__ && check_fgt_bit(vcpu->kvm, is_read,
@@ -2089,6 +2089,26 @@ bool __check_nv_sr_forward(struct kvm_vcpu *vcpu) 
	    ((b & BEHAVE_FORWARD_WRITE) && !is_read))

		goto inject;



local:

	if (!tc.sri) {

		struct sys_reg_params params;



		params = esr_sys64_to_params(esr);



		/*

		 * Check for the IMPDEF range, as per DDI0487 J.a,

		 * D18.3.2 Reserved encodings for IMPLEMENTATION

		 * DEFINED registers.

		 */

		if (!(params.Op0 == 3 && (params.CRn & 0b1011) == 0b1011))

			print_sys_reg_msg(&params,

					  "Unsupported guest access at: %lx\n",

					  *vcpu_pc(vcpu));

		kvm_inject_undefined(vcpu);

		return true;

	}



	*sr_index = tc.sri - 1;

	return false;



inject:

arch/arm64/kvm/sys_regs.c

+19 −44
Original line number Diff line number Diff line
@@ -3395,12 +3395,6 @@ int kvm_handle_cp14_32(struct kvm_vcpu *vcpu) 
	return kvm_handle_cp_32(vcpu, &params, cp14_regs, ARRAY_SIZE(cp14_regs));

}



static bool is_imp_def_sys_reg(struct sys_reg_params *params)

{

	// See ARM DDI 0487E.a, section D12.3.2

	return params->Op0 == 3 && (params->CRn & 0b1011) == 0b1011;

}



/**

 * emulate_sys_reg - Emulate a guest access to an AArch64 system register

 * @vcpu: The VCPU pointer
@@ -3414,39 +3408,17 @@ static bool emulate_sys_reg(struct kvm_vcpu *vcpu, 
	const struct sys_reg_desc *r;



	r = find_reg(params, sys_reg_descs, ARRAY_SIZE(sys_reg_descs));



	if (likely(r)) {

		perform_access(vcpu, params, r);

		return true;

	}



	if (is_imp_def_sys_reg(params)) {

		kvm_inject_undefined(vcpu);

	} else {

	print_sys_reg_msg(params,

			  "Unsupported guest sys_reg access at: %lx [%08lx]\n",

			  *vcpu_pc(vcpu), *vcpu_cpsr(vcpu));

	kvm_inject_undefined(vcpu);

	}

	return false;

}



static int emulate_sys_instr(struct kvm_vcpu *vcpu, struct sys_reg_params *p)

{

	const struct sys_reg_desc *r;



	/* Search from the system instruction table. */

	r = find_reg(p, sys_insn_descs, ARRAY_SIZE(sys_insn_descs));



	if (likely(r)) {

		perform_access(vcpu, p, r);

	} else {

		kvm_err("Unsupported guest sys instruction at: %lx\n",

			*vcpu_pc(vcpu));

		print_sys_reg_instr(p);

		kvm_inject_undefined(vcpu);

	}

	return 1;

	return false;

}



static void kvm_reset_id_regs(struct kvm_vcpu *vcpu)
@@ -3502,33 +3474,36 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu) 
 */

int kvm_handle_sys_reg(struct kvm_vcpu *vcpu)

{

	const struct sys_reg_desc *desc = NULL;

	struct sys_reg_params params;

	unsigned long esr = kvm_vcpu_get_esr(vcpu);

	int Rt = kvm_vcpu_sys_get_rt(vcpu);

	int sr_idx;



	trace_kvm_handle_sys_reg(esr);



	if (__check_nv_sr_forward(vcpu))

	if (__check_nv_sr_forward(vcpu, &sr_idx))

		return 1;



	params = esr_sys64_to_params(esr);

	params.regval = vcpu_get_reg(vcpu, Rt);



	/* System registers have Op0=={2,3}, as per DDI487 J.a C5.1.2 */

	if (params.Op0 == 2 || params.Op0 == 3) {

		if (!emulate_sys_reg(vcpu, &params))

			return 1;

	if (params.Op0 == 2 || params.Op0 == 3)

		desc = &sys_reg_descs[sr_idx];

	else

		desc = &sys_insn_descs[sr_idx];



		if (!params.is_write)

	perform_access(vcpu, &params, desc);



	/* Read from system register? */

	if (!params.is_write &&

	    (params.Op0 == 2 || params.Op0 == 3))

		vcpu_set_reg(vcpu, Rt, params.regval);



	return 1;

}



	/* Hints, PSTATE (Op0 == 0) and System instructions (Op0 == 1) */

	return emulate_sys_instr(vcpu, &params);

}



/******************************************************************************

 * Userspace API

 *****************************************************************************/