Commit 4cab5c85 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm64: Hide CNTHV_*_EL2 from userspace for nVHE guests 



Although we correctly UNDEF any CNTHV_*_EL2 access from the guest
when E2H==0, we still expose these registers to userspace, which
is a bad idea.

Drop the ad-hoc UNDEF injection and switch to a .visibility()
callback which will also hide the register from userspace.

Fixes: 0e459810 ("KVM: arm64: timer: Don't adjust the EL2 virtual timer offset")
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 164ecbf7

arch/arm64/kvm/sys_regs.c

+13 −13
Original line number Diff line number Diff line
@@ -1594,16 +1594,6 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu, 
	return true;

}



static bool access_hv_timer(struct kvm_vcpu *vcpu,

			    struct sys_reg_params *p,

			    const struct sys_reg_desc *r)

{

	if (!vcpu_el2_e2h_is_set(vcpu))

		return undef_access(vcpu, p, r);



	return access_arch_timer(vcpu, p, r);

}



static s64 kvm_arm64_ftr_safe_value(u32 id, const struct arm64_ftr_bits *ftrp,

				    s64 new, s64 cur)

{
@@ -2831,6 +2821,16 @@ static unsigned int s1pie_el2_visibility(const struct kvm_vcpu *vcpu, 
	return __el2_visibility(vcpu, rd, s1pie_visibility);

}



static unsigned int cnthv_visibility(const struct kvm_vcpu *vcpu,

				     const struct sys_reg_desc *rd)

{

	if (vcpu_has_nv(vcpu) &&

	    !vcpu_has_feature(vcpu, KVM_ARM_VCPU_HAS_EL2_E2H0))

		return 0;



	return REG_HIDDEN;

}



static bool access_mdcr(struct kvm_vcpu *vcpu,

			struct sys_reg_params *p,

			const struct sys_reg_desc *r)
@@ -3691,9 +3691,9 @@ static const struct sys_reg_desc sys_reg_descs[] = { 
	EL2_REG(CNTHP_CTL_EL2, access_arch_timer, reset_val, 0),

	EL2_REG(CNTHP_CVAL_EL2, access_arch_timer, reset_val, 0),



	{ SYS_DESC(SYS_CNTHV_TVAL_EL2), access_hv_timer },

	EL2_REG(CNTHV_CTL_EL2, access_hv_timer, reset_val, 0),

	EL2_REG(CNTHV_CVAL_EL2, access_hv_timer, reset_val, 0),

	{ SYS_DESC(SYS_CNTHV_TVAL_EL2), access_arch_timer, .visibility = cnthv_visibility },

	EL2_REG_FILTERED(CNTHV_CTL_EL2, access_arch_timer, reset_val, 0, cnthv_visibility),

	EL2_REG_FILTERED(CNTHV_CVAL_EL2, access_arch_timer, reset_val, 0, cnthv_visibility),



	{ SYS_DESC(SYS_CNTKCTL_EL12), access_cntkctl_el12 },