[PATCH v1 22/26] KVM: arm64: Refactor core reg handling
From: Steffen Eiden
Date: Fri May 29 2026 - 13:08:53 EST
Refactor sysreg core handling. Before this all core regs are identified
with a memory address and reading/writing happened through accessing the
data at this address. However, for arm64 on s390 not all core registers
have a dedicated memory address.
Refactor such that the address function does not return an address but
actually does the read/write request. ELR_EL1 and SPSR_EL1 now use
vcpu_read_sys_reg/vcpu_write_sys_reg accessor functions, allowing s390
to provide custom implementations.
Co-developed-by: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx>
Signed-off-by: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx>
Signed-off-by: Steffen Eiden <seiden@xxxxxxxxxxxxx>
---
virt/kvm/arm64/guest.c | 100 ++++++++++++++++++++++++++---------------
1 file changed, 64 insertions(+), 36 deletions(-)
diff --git a/virt/kvm/arm64/guest.c b/virt/kvm/arm64/guest.c
index 35ba03033b4c..11509382d594 100644
--- a/virt/kvm/arm64/guest.c
+++ b/virt/kvm/arm64/guest.c
@@ -65,69 +65,96 @@ static int core_reg_size_from_offset(const struct kvm_vcpu *vcpu, u64 off)
return size;
}
-static void *core_reg_addr(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
+static int core_reg_rw(struct kvm_vcpu *vcpu, u64 reg_id, void *valp, bool read)
{
- u64 off = core_reg_offset_from_id(reg->id);
+ u64 off = core_reg_offset_from_id(reg_id);
int size = core_reg_size_from_offset(vcpu, off);
+ void *addr;
- if (size < 0)
- return NULL;
+ if (size < 0 || (KVM_REG_SIZE(reg_id) != size))
+ return -EINVAL;
- if (KVM_REG_SIZE(reg->id) != size)
- return NULL;
+ switch (off) {
+ case KVM_REG_ARM_CORE_REG(elr_el1):
+ if (read)
+ *(u64 *)valp = vcpu_read_sys_reg(vcpu, ELR_EL1);
+ else
+ vcpu_write_sys_reg(vcpu, *(u64 *)valp, ELR_EL1);
+ return 0;
+
+ case KVM_REG_ARM_CORE_REG(spsr[KVM_SPSR_EL1]):
+ if (read)
+ *(u64 *)valp = vcpu_read_sys_reg(vcpu, SPSR_EL1);
+ else
+ vcpu_write_sys_reg(vcpu, *(u64 *)valp, SPSR_EL1);
+ return 0;
+ }
switch (off) {
case KVM_REG_ARM_CORE_REG(regs.regs[0]) ...
KVM_REG_ARM_CORE_REG(regs.regs[30]):
off -= KVM_REG_ARM_CORE_REG(regs.regs[0]);
off /= 2;
- return &vcpu_gp_regs(vcpu)[off];
+ addr = &vcpu_gp_regs(vcpu)[off];
+ break;
case KVM_REG_ARM_CORE_REG(regs.sp):
- return vcpu_sp_el0(vcpu);
+ addr = vcpu_sp_el0(vcpu);
+ break;
case KVM_REG_ARM_CORE_REG(regs.pc):
- return vcpu_pc(vcpu);
+ addr = vcpu_pc(vcpu);
+ break;
case KVM_REG_ARM_CORE_REG(regs.pstate):
- return vcpu_cpsr(vcpu);
+ addr = vcpu_cpsr(vcpu);
+ break;
case KVM_REG_ARM_CORE_REG(sp_el1):
- return kvm_vcpu_get_sp_el1(vcpu);
-
- case KVM_REG_ARM_CORE_REG(elr_el1):
- return __ctxt_sys_reg(&vcpu->arch.ctxt, ELR_EL1);
-
- case KVM_REG_ARM_CORE_REG(spsr[KVM_SPSR_EL1]):
- return __ctxt_sys_reg(&vcpu->arch.ctxt, SPSR_EL1);
+ addr = kvm_vcpu_get_sp_el1(vcpu);
+ break;
case KVM_REG_ARM_CORE_REG(spsr[KVM_SPSR_ABT]):
- return &vcpu->arch.ctxt.spsr_abt;
+ addr = &vcpu->arch.ctxt.spsr_abt;
+ break;
case KVM_REG_ARM_CORE_REG(spsr[KVM_SPSR_UND]):
- return &vcpu->arch.ctxt.spsr_und;
+ addr = &vcpu->arch.ctxt.spsr_und;
+ break;
case KVM_REG_ARM_CORE_REG(spsr[KVM_SPSR_IRQ]):
- return &vcpu->arch.ctxt.spsr_irq;
+ addr = &vcpu->arch.ctxt.spsr_irq;
+ break;
case KVM_REG_ARM_CORE_REG(spsr[KVM_SPSR_FIQ]):
- return &vcpu->arch.ctxt.spsr_fiq;
+ addr = &vcpu->arch.ctxt.spsr_fiq;
+ break;
case KVM_REG_ARM_CORE_REG(fp_regs.vregs[0]) ...
KVM_REG_ARM_CORE_REG(fp_regs.vregs[31]):
off -= KVM_REG_ARM_CORE_REG(fp_regs.vregs[0]);
off /= 4;
- return kvm_vcpu_get_vreg(vcpu, off);
+ addr = kvm_vcpu_get_vreg(vcpu, off);
+ break;
case KVM_REG_ARM_CORE_REG(fp_regs.fpsr):
- return kvm_vcpu_get_fpsr(vcpu);
+ addr = kvm_vcpu_get_fpsr(vcpu);
+ break;
case KVM_REG_ARM_CORE_REG(fp_regs.fpcr):
- return kvm_vcpu_get_fpcr(vcpu);
+ addr = kvm_vcpu_get_fpcr(vcpu);
+ break;
default:
- return NULL;
+ return -EINVAL;
}
+
+ if (read)
+ memcpy(valp, addr, size);
+ else
+ memcpy(addr, valp, size);
+
+ return 0;
}
int get_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
@@ -140,7 +167,9 @@ int get_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
*/
__u32 __user *uaddr = (__u32 __user *)(unsigned long)reg->addr;
int nr_regs = sizeof(struct kvm_regs) / sizeof(__u32);
- void *addr;
+ __uint128_t tmp;
+ void *valp = &tmp;
+ int ret;
u32 off;
/* Our ID is an index into the kvm_regs struct. */
@@ -149,11 +178,12 @@ int get_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
(off + (KVM_REG_SIZE(reg->id) / sizeof(__u32))) >= nr_regs)
return -ENOENT;
- addr = core_reg_addr(vcpu, reg);
- if (!addr)
- return -EINVAL;
- if (copy_to_user(uaddr, addr, KVM_REG_SIZE(reg->id)))
+ ret = core_reg_rw(vcpu, reg->id, valp, true);
+ if (ret)
+ return ret;
+
+ if (copy_to_user(uaddr, valp, KVM_REG_SIZE(reg->id)))
return -EFAULT;
return 0;
@@ -164,7 +194,7 @@ int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
__u32 __user *uaddr = (__u32 __user *)(unsigned long)reg->addr;
int nr_regs = sizeof(struct kvm_regs) / sizeof(__u32);
__uint128_t tmp;
- void *valp = &tmp, *addr;
+ void *valp = &tmp;
u64 off;
int err = 0;
@@ -174,10 +204,6 @@ int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
(off + (KVM_REG_SIZE(reg->id) / sizeof(__u32))) >= nr_regs)
return -ENOENT;
- addr = core_reg_addr(vcpu, reg);
- if (!addr)
- return -EINVAL;
-
if (KVM_REG_SIZE(reg->id) > sizeof(tmp))
return -EINVAL;
@@ -220,7 +246,9 @@ int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
}
}
- memcpy(addr, valp, KVM_REG_SIZE(reg->id));
+ err = core_reg_rw(vcpu, reg->id, valp, false);
+ if (err)
+ goto out;
if (*vcpu_cpsr(vcpu) & PSR_MODE32_BIT) {
int i, nr_reg;
--
2.53.0