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KVM: arm64: nv: Don't treat ZCR_EL2 as a 'mapped' register 

Unlike the other mapped EL2 sysregs ZCR_EL2 isn't guaranteed to be
resident when a vCPU is loaded as it actually follows the SVE
context. As such, the contents of ZCR_EL1 may belong to another guest if
the vCPU has been preempted before reaching sysreg emulation.

Unconditionally use the in-memory value of ZCR_EL2 and switch to the
memory-only accessors. The in-memory value is guaranteed to be valid as
fpsimd_lazy_switch_to_{guest,host}() will restore/save the register
appropriately.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Oliver Upton 2025-09-26 12:41:07 -07:00 committed by Marc Zyngier
parent 3a86608788
commit ed25dcfbc4
1 changed files with 2 additions and 4 deletions
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6
arch/arm64/kvm/sys_regs.c
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@ -203,7 +203,6 @@ static void locate_register(const struct kvm_vcpu *vcpu, enum vcpu_sysreg reg,
MAPPED_EL2_SYSREG(AMAIR_EL2, AMAIR_EL1, NULL ); MAPPED_EL2_SYSREG(AMAIR_EL2, AMAIR_EL1, NULL );
MAPPED_EL2_SYSREG(ELR_EL2, ELR_EL1, NULL ); MAPPED_EL2_SYSREG(ELR_EL2, ELR_EL1, NULL );
MAPPED_EL2_SYSREG(SPSR_EL2, SPSR_EL1, NULL ); MAPPED_EL2_SYSREG(SPSR_EL2, SPSR_EL1, NULL );
MAPPED_EL2_SYSREG(ZCR_EL2, ZCR_EL1, NULL );
MAPPED_EL2_SYSREG(CONTEXTIDR_EL2, CONTEXTIDR_EL1, NULL ); MAPPED_EL2_SYSREG(CONTEXTIDR_EL2, CONTEXTIDR_EL1, NULL );
MAPPED_EL2_SYSREG(SCTLR2_EL2, SCTLR2_EL1, NULL ); MAPPED_EL2_SYSREG(SCTLR2_EL2, SCTLR2_EL1, NULL );
case CNTHCTL_EL2: case CNTHCTL_EL2:
@ -2709,14 +2708,13 @@ static bool access_zcr_el2(struct kvm_vcpu *vcpu,
} }
if (!p->is_write) { if (!p->is_write) {
p->regval = vcpu_read_sys_reg(vcpu, ZCR_EL2); p->regval = __vcpu_sys_reg(vcpu, ZCR_EL2);
return true; return true;
} }
vq = SYS_FIELD_GET(ZCR_ELx, LEN, p->regval) + 1; vq = SYS_FIELD_GET(ZCR_ELx, LEN, p->regval) + 1;
vq = min(vq, vcpu_sve_max_vq(vcpu)); vq = min(vq, vcpu_sve_max_vq(vcpu));
vcpu_write_sys_reg(vcpu, vq - 1, ZCR_EL2); __vcpu_assign_sys_reg(vcpu, ZCR_EL2, vq - 1);
return true; return true;
} }