From: Oliver Upton <oupton@kernel.org>
To: kvmarm@lists.linux.dev
Cc: Marc Zyngier <maz@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Wei-Lin Chang <weilin.chang@arm.com>,
Steffen Eiden <seiden@linux.ibm.com>,
Fuad Tabba <fuad.tabba@linux.dev>,
Oliver Upton <oupton@kernel.org>
Subject: [PATCH 3/8] KVM: arm64: Separate user / guest visibility flags
Date: Wed, 4 Nov 2026 11:21:19 -0800 [thread overview]
Message-ID: <20261104192124.3932743-4-oupton@kernel.org> (raw)
In-Reply-To: <20261104192124.3932743-1-oupton@kernel.org>
There's need for even more visibility hacks to differentiate between
userspace and guest. Decompose REG_HIDDEN into two parts and test for
the user-specific flag on all the appropriate UAPI surfaces.
Signed-off-by: Oliver Upton <oupton@kernel.org>
---
arch/arm64/kvm/sys_regs.c | 10 +++++-----
arch/arm64/kvm/sys_regs.h | 23 +++++++++++++++++------
arch/arm64/kvm/vgic-sys-reg-v3.c | 2 +-
arch/arm64/kvm/vgic-sys-reg-v5.c | 2 +-
4 files changed, 24 insertions(+), 13 deletions(-)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 850eba167aad..870dcb25d0d7 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -4866,7 +4866,7 @@ static void perform_access(struct kvm_vcpu *vcpu,
trace_kvm_sys_access(*vcpu_pc(vcpu), params, r);
/* Check for regs disabled by runtime config */
- if (sysreg_hidden(vcpu, r)) {
+ if (sysreg_guest_hidden(vcpu, r)) {
kvm_inject_undefined(vcpu);
return;
}
@@ -5490,7 +5490,7 @@ id_to_sys_reg_desc(struct kvm_vcpu *vcpu, u64 id,
r = get_reg_by_id(id, table, num);
/* Not saved in the sys_reg array and not otherwise accessible? */
- if (r && (!(r->reg || r->get_user) || sysreg_hidden(vcpu, r)))
+ if (r && (!(r->reg || r->get_user) || sysreg_user_hidden(vcpu, r)))
r = NULL;
return r;
@@ -5571,7 +5571,7 @@ 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, id, table, num);
- if (!r || sysreg_hidden(vcpu, r))
+ if (!r || sysreg_user_hidden(vcpu, r))
return -ENOENT;
if (r->get_user) {
@@ -5611,7 +5611,7 @@ 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, id, table, num);
- if (!r || sysreg_hidden(vcpu, r))
+ if (!r || sysreg_user_hidden(vcpu, r))
return -ENOENT;
if (sysreg_user_write_ignore(vcpu, r))
@@ -5705,7 +5705,7 @@ 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_user_hidden(vcpu, rd))
return 0;
if (!copy_reg_to_user(rd, uind))
diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index a3cccad2766f..50214271b24a 100644
--- a/arch/arm64/kvm/sys_regs.h
+++ b/arch/arm64/kvm/sys_regs.h
@@ -104,9 +104,14 @@ struct sys_reg_desc {
const struct sys_reg_desc *rd);
};
-#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_GUEST_HIDDEN BIT(0)
+#define REG_USER_HIDDEN BIT(1)
+ /* Hidden from userspace and guest */
+#define REG_HIDDEN (REG_GUEST_HIDDEN | REG_USER_HIDDEN)
+ /* RAZ from userspace and guest */
+#define REG_RAZ BIT(2)
+ /* WI from userspace only */
+#define REG_USER_WI BIT(3)
static __printf(2, 3)
inline void print_sys_reg_msg(const struct sys_reg_params *p,
@@ -168,10 +173,16 @@ static inline unsigned int sysreg_visibility(const struct kvm_vcpu *vcpu,
return r->visibility(vcpu, r);
}
-static inline bool sysreg_hidden(const struct kvm_vcpu *vcpu,
- const struct sys_reg_desc *r)
+static inline bool sysreg_user_hidden(const struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *r)
+{
+ return sysreg_visibility(vcpu, r) & REG_USER_HIDDEN;
+}
+
+static inline bool sysreg_guest_hidden(const struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *r)
{
- return sysreg_visibility(vcpu, r) & REG_HIDDEN;
+ return sysreg_visibility(vcpu, r) & REG_GUEST_HIDDEN;
}
static inline bool sysreg_visible_as_raz(const struct kvm_vcpu *vcpu,
diff --git a/arch/arm64/kvm/vgic-sys-reg-v3.c b/arch/arm64/kvm/vgic-sys-reg-v3.c
index 89315336b9d3..f41c21ee9e89 100644
--- a/arch/arm64/kvm/vgic-sys-reg-v3.c
+++ b/arch/arm64/kvm/vgic-sys-reg-v3.c
@@ -465,7 +465,7 @@ int vgic_v3_has_cpu_sysregs_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *
r = get_reg_by_id(attr_to_id(attr->attr), gic_v3_icc_reg_descs,
ARRAY_SIZE(gic_v3_icc_reg_descs));
- if (r && !sysreg_hidden(vcpu, r))
+ if (r && !sysreg_user_hidden(vcpu, r))
return 0;
return -ENXIO;
diff --git a/arch/arm64/kvm/vgic-sys-reg-v5.c b/arch/arm64/kvm/vgic-sys-reg-v5.c
index 6b255eacbf60..e62d5e908f5a 100644
--- a/arch/arm64/kvm/vgic-sys-reg-v5.c
+++ b/arch/arm64/kvm/vgic-sys-reg-v5.c
@@ -495,7 +495,7 @@ int vgic_v5_has_cpu_sysregs_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *
r = get_reg_by_id(attr_to_id(attr->attr), gic_v5_icc_reg_descs,
ARRAY_SIZE(gic_v5_icc_reg_descs));
- if (r && !sysreg_hidden(vcpu, r))
+ if (r && !sysreg_user_hidden(vcpu, r))
return 0;
return -ENXIO;
--
2.47.3
next prev parent reply other threads:[~2026-11-04 19:21 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-04 19:21 [PATCH 0/8] KVM: arm64: Prefix of fixes from HAFDBS series (for 7.4) Oliver Upton
2026-11-04 19:21 ` [PATCH 1/8] KVM: arm64: nv: Disallow KVM_CAP_ARM_MTE + FEAT_EL2 Oliver Upton
2026-11-04 19:37 ` sashiko-bot
2026-11-04 20:17 ` Oliver Upton
2026-11-04 19:21 ` [PATCH 2/8] KVM: arm64: nv: Add CGT description for FEAT_PoPS instructions Oliver Upton
2026-11-05 18:12 ` Leonardo Bras
2026-11-04 19:21 ` Oliver Upton [this message]
2026-11-04 19:21 ` [PATCH 4/8] KVM: arm64: nv: Treat the VNCR GICv3 registers as hidden from user Oliver Upton
2026-11-04 19:21 ` [PATCH 5/8] KVM: arm64: Use ->visibility() to filter MTE CMO instructions Oliver Upton
2026-11-04 19:21 ` [PATCH 6/8] KVM: arm64: Add sys_reg_descs for remaining " Oliver Upton
2026-11-04 19:21 ` [PATCH 7/8] KVM: arm64: nv: Enforce sysreg visibility before evaulating guest traps Oliver Upton
2026-11-04 19:21 ` [PATCH 8/8] KVM: arm64: Stop leaning on __kvm_inject_sea() for abort injection Oliver Upton
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