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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: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230209175820.1939006-16-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Marc Zyngier 2023-02-09 17:58:17 +00:00 committed by Oliver Upton
parent d9552fe133
commit e6b367db0f
2 changed files with 15 additions and 5 deletions
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6
arch/arm64/kvm/sys_regs.c
View File

@ -2980,7 +2980,7 @@ int kvm_sys_reg_get_user(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg,
int ret; int ret;
r = id_to_sys_reg_desc(vcpu, reg->id, table, num); r = id_to_sys_reg_desc(vcpu, reg->id, table, num);
if (!r) if (!r || sysreg_hidden_user(vcpu, r))
return -ENOENT; return -ENOENT;
if (r->get_user) { 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; return -EFAULT;
r = id_to_sys_reg_desc(vcpu, reg->id, table, num); r = id_to_sys_reg_desc(vcpu, reg->id, table, num);
if (!r) if (!r || sysreg_hidden_user(vcpu, r))
return -ENOENT; return -ENOENT;
if (sysreg_user_write_ignore(vcpu, r)) 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)) if (!(rd->reg || rd->get_user))
return 0; return 0;
if (sysreg_hidden(vcpu, rd)) if (sysreg_hidden_user(vcpu, rd))
return 0; return 0;
if (!copy_reg_to_user(rd, uind)) if (!copy_reg_to_user(rd, uind))

14
arch/arm64/kvm/sys_regs.h
View File

@ -85,8 +85,9 @@ struct sys_reg_desc {
}; };
#define REG_HIDDEN (1 << 0) /* hidden from userspace and guest */ #define REG_HIDDEN (1 << 0) /* hidden from userspace and guest */
#define REG_RAZ (1 << 1) /* RAZ from userspace and guest */ #define REG_HIDDEN_USER (1 << 1) /* hidden from userspace only */
#define REG_USER_WI (1 << 2) /* WI 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) static __printf(2, 3)
inline void print_sys_reg_msg(const struct sys_reg_params *p, 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; 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, static inline bool sysreg_visible_as_raz(const struct kvm_vcpu *vcpu,
const struct sys_reg_desc *r) const struct sys_reg_desc *r)
{ {