Commit e6b367db authored by Marc Zyngier's avatar Marc Zyngier Committed by Oliver Upton
Browse files

KVM: arm64: nv: Allow a sysreg to be hidden from userspace only 



So far, we never needed to distinguish between registers hidden
from userspace and being hidden from a guest (they are always
either visible to both, or hidden from both).

With NV, we have the ugly case of the EL02 and EL12 registers,
which are only a view on the EL0 and EL1 registers. It makes
absolutely no sense to expose them to userspace, since it
already has the canonical view.

Add a new visibility flag (REG_HIDDEN_USER) and a new helper that
checks for it and REG_HIDDEN when checking whether to expose
a sysreg to userspace. Subsequent patches will make use of it.

Reviewed-by: default avatarAlexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230209175820.1939006-16-maz@kernel.org


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent d9552fe1

arch/arm64/kvm/sys_regs.c

+3 −3
Original line number Diff line number Diff line
@@ -2980,7 +2980,7 @@ int kvm_sys_reg_get_user(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg, 
	int ret;



	r = id_to_sys_reg_desc(vcpu, reg->id, table, num);

	if (!r)

	if (!r || sysreg_hidden_user(vcpu, r))

		return -ENOENT;



	if (r->get_user) {
@@ -3024,7 +3024,7 @@ int kvm_sys_reg_set_user(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg, 
		return -EFAULT;



	r = id_to_sys_reg_desc(vcpu, reg->id, table, num);

	if (!r)

	if (!r || sysreg_hidden_user(vcpu, r))

		return -ENOENT;



	if (sysreg_user_write_ignore(vcpu, r))
@@ -3118,7 +3118,7 @@ static int walk_one_sys_reg(const struct kvm_vcpu *vcpu, 
	if (!(rd->reg || rd->get_user))

		return 0;



	if (sysreg_hidden(vcpu, rd))

	if (sysreg_hidden_user(vcpu, rd))

		return 0;



	if (!copy_reg_to_user(rd, uind))

arch/arm64/kvm/sys_regs.h

+12 −2
Original line number Diff line number Diff line
@@ -85,8 +85,9 @@ struct sys_reg_desc { 
};



#define REG_HIDDEN		(1 << 0) /* hidden from userspace and guest */

#define REG_RAZ			(1 << 1) /* RAZ from userspace and guest */

#define REG_USER_WI		(1 << 2) /* WI from userspace only */

#define REG_HIDDEN_USER		(1 << 1) /* hidden from userspace only */

#define REG_RAZ			(1 << 2) /* RAZ from userspace and guest */

#define REG_USER_WI		(1 << 3) /* WI from userspace only */



static __printf(2, 3)

inline void print_sys_reg_msg(const struct sys_reg_params *p,
@@ -152,6 +153,15 @@ static inline bool sysreg_hidden(const struct kvm_vcpu *vcpu, 
	return sysreg_visibility(vcpu, r) & REG_HIDDEN;

}



static inline bool sysreg_hidden_user(const struct kvm_vcpu *vcpu,

				      const struct sys_reg_desc *r)

{

	if (likely(!r->visibility))

		return false;



	return r->visibility(vcpu, r) & (REG_HIDDEN | REG_HIDDEN_USER);

}



static inline bool sysreg_visible_as_raz(const struct kvm_vcpu *vcpu,

					 const struct sys_reg_desc *r)

{