[PATCH v5 2/8] KVM: arm64: Make vcpu_{read,write}_sys_reg available to HYP code
From: Fuad Tabba <hidden>
Date: 2026-07-14 10:16:43
Also in:
kvmarm, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
The vcpu_{read,write}_sys_reg() accessors are only valid on a VHE host,
so helpers built on them such as kvm_vcpu_set_be()/kvm_vcpu_is_be()
cannot be shared with hyp code. exception.c already wraps them in local
helpers that pick the host- or hyp-side accessor via has_vhe().
Rename the host-only implementations to __vcpu_{read,write}_sysreg_vhe()
and turn vcpu_{read,write}_sys_reg() into the context-dispatching
wrappers, so every caller gets the version valid in any context and a
follow-up series can share that emulation code at EL2.
No functional change intended.
Signed-off-by: Fuad Tabba <redacted>
---
v5:
- Named the wrappers vcpu_{read,write}_sys_reg() and renamed the
host-only implementations to __vcpu_{read,write}_sysreg_vhe(), rather
than introducing a kvm_vcpu_ prefix. (Oliver)
- Dropped Vincent's Reviewed-by since the patch changed materially.
arch/arm64/include/asm/kvm_emulate.h | 20 ++++++++++++++++
arch/arm64/include/asm/kvm_host.h | 4 ++--
arch/arm64/kvm/hyp/exception.c | 34 ++++++++--------------------
arch/arm64/kvm/sys_regs.c | 4 ++--
4 files changed, 33 insertions(+), 29 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 5bf3d7e1d92c7..429bda6f48d94 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h@@ -506,6 +506,26 @@ static inline unsigned long kvm_vcpu_get_mpidr_aff(struct kvm_vcpu *vcpu) return __vcpu_sys_reg(vcpu, MPIDR_EL1) & MPIDR_HWID_BITMASK; } +/* + * __vcpu_*_sysreg_vhe() are only valid on a VHE host; wrap them so the same + * call site also works at EL2 under nVHE. + */ +static inline u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, enum vcpu_sysreg reg) +{ + if (has_vhe()) + return __vcpu_read_sysreg_vhe(vcpu, reg); + + return __vcpu_sys_reg(vcpu, reg); +} + +static inline void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, enum vcpu_sysreg reg) +{ + if (has_vhe()) + __vcpu_write_sysreg_vhe(vcpu, val, reg); + else + __vcpu_assign_sys_reg(vcpu, reg, val); +} + static inline void kvm_vcpu_set_be(struct kvm_vcpu *vcpu) { if (vcpu_mode_is_32bit(vcpu)) {
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index bae2c4f92ef5c..f3c3c86b3d7fb 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h@@ -1215,8 +1215,8 @@ u64 kvm_vcpu_apply_reg_masks(const struct kvm_vcpu *, enum vcpu_sysreg, u64); __v; \ }) -u64 vcpu_read_sys_reg(const struct kvm_vcpu *, enum vcpu_sysreg); -void vcpu_write_sys_reg(struct kvm_vcpu *, u64, enum vcpu_sysreg); +u64 __vcpu_read_sysreg_vhe(const struct kvm_vcpu *vcpu, enum vcpu_sysreg reg); +void __vcpu_write_sysreg_vhe(struct kvm_vcpu *vcpu, u64 val, enum vcpu_sysreg reg); struct kvm_vm_stat { struct kvm_vm_stat_generic generic;
diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c
index bef40ddb16dbc..754e2dc1df54a 100644
--- a/arch/arm64/kvm/hyp/exception.c
+++ b/arch/arm64/kvm/hyp/exception.c@@ -20,22 +20,6 @@ #error Hypervisor code only! #endif -static inline u64 __vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg) -{ - if (has_vhe()) - return vcpu_read_sys_reg(vcpu, reg); - - return __vcpu_sys_reg(vcpu, reg); -} - -static inline void __vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg) -{ - if (has_vhe()) - vcpu_write_sys_reg(vcpu, val, reg); - else - __vcpu_assign_sys_reg(vcpu, reg, val); -} - static void __vcpu_write_spsr(struct kvm_vcpu *vcpu, unsigned long target_mode, u64 val) {
@@ -101,14 +85,14 @@ static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode, switch (target_mode) { case PSR_MODE_EL1h: - vbar = __vcpu_read_sys_reg(vcpu, VBAR_EL1); - sctlr = __vcpu_read_sys_reg(vcpu, SCTLR_EL1); - __vcpu_write_sys_reg(vcpu, *vcpu_pc(vcpu), ELR_EL1); + vbar = vcpu_read_sys_reg(vcpu, VBAR_EL1); + sctlr = vcpu_read_sys_reg(vcpu, SCTLR_EL1); + vcpu_write_sys_reg(vcpu, *vcpu_pc(vcpu), ELR_EL1); break; case PSR_MODE_EL2h: - vbar = __vcpu_read_sys_reg(vcpu, VBAR_EL2); - sctlr = __vcpu_read_sys_reg(vcpu, SCTLR_EL2); - __vcpu_write_sys_reg(vcpu, *vcpu_pc(vcpu), ELR_EL2); + vbar = vcpu_read_sys_reg(vcpu, VBAR_EL2); + sctlr = vcpu_read_sys_reg(vcpu, SCTLR_EL2); + vcpu_write_sys_reg(vcpu, *vcpu_pc(vcpu), ELR_EL2); break; default: /* Don't do that */
@@ -185,7 +169,7 @@ static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode, */ static unsigned long get_except32_cpsr(struct kvm_vcpu *vcpu, u32 mode) { - u32 sctlr = __vcpu_read_sys_reg(vcpu, SCTLR_EL1); + u32 sctlr = vcpu_read_sys_reg(vcpu, SCTLR_EL1); unsigned long old, new; old = *vcpu_cpsr(vcpu);
@@ -281,7 +265,7 @@ static void enter_exception32(struct kvm_vcpu *vcpu, u32 mode, u32 vect_offset) { unsigned long spsr = *vcpu_cpsr(vcpu); bool is_thumb = (spsr & PSR_AA32_T_BIT); - u32 sctlr = __vcpu_read_sys_reg(vcpu, SCTLR_EL1); + u32 sctlr = vcpu_read_sys_reg(vcpu, SCTLR_EL1); u32 return_address; *vcpu_cpsr(vcpu) = get_except32_cpsr(vcpu, mode);
@@ -305,7 +289,7 @@ static void enter_exception32(struct kvm_vcpu *vcpu, u32 mode, u32 vect_offset) if (sctlr & (1 << 13)) vect_offset += 0xffff0000; else /* always have security exceptions */ - vect_offset += __vcpu_read_sys_reg(vcpu, VBAR_EL1); + vect_offset += vcpu_read_sys_reg(vcpu, VBAR_EL1); *vcpu_pc(vcpu) = vect_offset; }
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 08ba882799d48..c6a416974a61f 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c@@ -291,7 +291,7 @@ static void write_sr_to_cpu(enum vcpu_sysreg reg, u64 val) } } -u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, enum vcpu_sysreg reg) +u64 __vcpu_read_sysreg_vhe(const struct kvm_vcpu *vcpu, enum vcpu_sysreg reg) { struct sr_loc loc = {};
@@ -338,7 +338,7 @@ u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, enum vcpu_sysreg reg) return __vcpu_sys_reg(vcpu, reg); } -void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, enum vcpu_sysreg reg) +void __vcpu_write_sysreg_vhe(struct kvm_vcpu *vcpu, u64 val, enum vcpu_sysreg reg) { struct sr_loc loc = {};
--
2.39.5